Wildguzzi.com
General Category => General Discussion => Topic started by: radguzzi on August 30, 2021, 06:54:59 PM
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The VHB 30 carbs on the '76 V1000 Convert are just plain worn out I fear, the fuel consumption is just ridiculous, it's bad. To the point where I want to buy new replacements. I am not finding any... :(
I have gone through all the usual procedures, correct jetting etc. to no avail.
Anyone here know of a source that I do not know of OR can I install PHF Dellorto 30s on that engine successfully and with simple cable changes...?
Thanks,
rad__
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If anyone would have new/NOS, it would probably be Harper's or Paul Szostak. Maybe a good used pair?
There are any number of other carburetors one can install, each has it own set of issues to overcome. Finding manifolds that work is the main problem, the Delrin manifolds put the carb at an shallower angle than the original manifolds (or the uncommon rubber elbows used around '81). It may be necessary to cut the sidecovers to make clearance for air filters.
George Dockeray (hope I spelled his name correctly) modified VHB manifolds to use the later rubber couple and PHFs. Very nicely done and looked nearly stock.
(https://i.ibb.co/cNkyPtR/George-Dockeray-PHFs.jpg) (https://ibb.co/cNkyPtR)
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The advice Charlie just gave is good.
Another possibility is this VHB to PHBH 30 replacement kit from Stein-Dinse:
https://www.stein-dinse.biz/product_info.php?products_id=1027
(https://www.stein-dinse.biz/product_info.php?products_id=1027)
It has been offered by them for many years.
Moto
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The advice Charlie just gave is good.
Another possibility is this VHB to PHBH 30 replacement kit from Stein-Dinse:
https://www.stein-dinse.biz/product_info.php?products_id=1027
(https://www.stein-dinse.biz/product_info.php?products_id=1027)
It has been offered by them for many years.
Moto
Original manifolds would need to be modified ("Just little modifications on sockets / draws essential."), similar to what George did.
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Could it be be the seals on the bottom of the choke plungers? Overly rich would suggest wrong needles or main jets. I flipped the rubber pads on the bottom of my choke plungers LMIII and cured the same overly rich problem, how are the plugs looking?
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If it is a too rich issue , needle and needle jet are probably worn. I have seen that a few times'
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Original manifolds would need to be modified ("Just little modifications on sockets / draws essential."), similar to what George did.
That's right. One drawback of the kit is the PHBH 30 carburetors. They are a bottom of the line version that has no accelerator pumps of either kind, as I recall. It would be nice to hear from someone who has experience having installed this item. The kit is quite cheap, I think.
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Could it be be the seals on the bottom of the choke plungers? Overly rich would suggest wrong needles or main jets. I flipped the rubber pads on the bottom of my choke plungers LMIII and cured the same overly rich problem, how are the plugs looking?
Good idea. I'm having some richness problem at idle myself. I just ordered two new plungers for $6 each, plus $3.46 shipping, from scramblercycle.com, in northern Wisconsin. A good source for many Guzzi and Dellorto parts.
Moto
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You can always get a set of Amal manifolds that came on '74 Eldorados for a while. Once you have those, you could install some brand new (and improved) Amals (930's I believe) or any of the chinese "amal" replacements. I have used the latter for years, even went 115 Land Speed Racing on my Automatic with them.
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Anyone here know of a source that I do not know of OR can I install PHF Dellorto 30s on that engine successfully and with simple cable changes...?
Random.
The problem might be elsewhere as suggested as far as richness.
The VHB's are rebuildable down to slides so as long as the body is not worn out, it is simply a matter of time and money.
I fully rebuilt the 29VHB's I have, done to the last component that warranted replacing.
I thought one of the early 80's engines came with 30 PHF's which would make it a bolt on if available.
Those 30 mm carburetors are cheap for a reason and being cast in Italy they might not be, including the cheesy white floats.
I put (1980's) 32 mm PHF's on the Eldorado (which is not a V1000 layout hough) but are similar to the 30's (same casting I believe)
I had a couple of sets so initial cost was low but they still cost a bundle to go through.
Googling showed it had been done before but most looked to have the carburetors on an angle due to the float bowls hitting the gearbox casing.
Larger spigot OD 30 mm VHB manifolds with machined spigots to suit the nylon sleeves in the PHF's.
(https://photos.imageevent.com/time_warp1959/motorcycle/mgmods/mn1.jpg)
Tapered gaskets to swing the manifolds outward slightly so the carburetors ae vertical.
(https://photos.imageevent.com/time_warp1959/motorcycle/mgmods/gsk.jpg)
Threaded adapters to suit the stock rubber air box boot.
(https://photos.imageevent.com/time_warp1959/motorcycle/mgmods/adt%202.jpg)
Almost like stock.
(https://photos.imageevent.com/time_warp1959/motorcycle/mgmods/phf_1.jpg)
It would be easier with the twin cable throttle as cables are available off the shelf. (Unlike to suit the 1 into 2 cable Super Pratic)
I did have to get custom cables and machined a rotary drum splitter.
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The plugs are sooty black. I did not do a plug chop, just pulled them out after putting the Vert up on a a stand at the end of a long ride.
When I recommissioned the Guzzi I "Went through" the carbs in that I put all the bits in the ultrasonic cleaner and inspected the parts and reinstalled them; jets etc...
So I wonder if I should at least just go through and go with new jets, needles, needle jets as @dblue suggests, atomizers etc. before I jump into the deep end and replace with the PHBs.
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@lucian,
New individual choke lever assemblies so I would discount that for now.
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@mtiberio,
I do have a new set of Amal Premier 930s for the '78 Triumph T140V, good idea there. Even though I will not be doing any LSR attempts.
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@LesP,
Nice work as usual sir...
More later.
Thanks all.
Rob
(https://imagizer.imageshack.com/v2/640x480q90/922/rG84OW.jpg)
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eurocarb in the uk
https://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/complete-carburettors-dellorto-motorcycle-carburettors-parts/phbe-30-to-38mm/r6808-dellorto-phbe-30hs/
very good people
I'm not sure that they ship to the USA, but if you want me to order them over here and ship them on to you I'd be more than happy to help
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Thanks lazlokovacs on the UK Carb outlet... I May have to contact you.
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So I opened the carbs to inspect and find out what the issue Might be...
I had also failed to mention that I am using K&N air filters With the runners ( stacks) on the carbs.
Wondering also If the issue could be float height related..? I have not yet measured for that setting.
Could that be a big factor for the poor fuel consumption..?
I have several questions about what I found.
The Main (125) and Idle (50) Jets,
Needle (V9) Not available new
Choke (80),
Idle Mixture Screw Taper & Shaft Length are up to spec with Guzziology.
The Slide is way out of whack, this is a 40 and Guzziology calls for a 60...? Not available new
Needle Clip in the middle position.
1/ The V9 Needle and #60 Slide seem to be No Longer Available...
2/ Guzziology talks about Pumps. This one has no ball in the body, it has the little strainer type thingy and a spring.
3/ How does one know which needle valve seat is installed...? Or I guess, more importantly, how is the seat changed...?
4/ Oh, the slide to wall ID is rather significant me thinks but open to verification. The clearance is ~ 0.024" - 0.025" on both the side to side and fore and aft measurement.
Does that mean that the bores are actually worn beyond life lifespan...
Uhhhg, I am so confused now... In that several components are not available I am not sure just which way to go.
Thanks for putting up with this mess.
Rob
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Thanks lazlokovacs on the UK Carb outlet... I May have to contact you.
Dellorto UK/Eurocarb are more than happy to sell to US customers, I've bought a fair bit of stuff from them.
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So I opened the carbs to inspect and find out what the issue Might be...
I had also failed to mention that I am using K&N air filters With the runners ( stacks) on the carbs.
Wondering also If the issue could be float height related..? I have not yet measured for that setting.
Could that be a big factor for the poor fuel consumption..?
I have several questions about what I found.
The Main (125) and Idle (50) Jets,
Needle (V9) Not available new
Choke (80),
Idle Mixture Screw Taper & Shaft Length are up to spec with Guzziology.
The Slide is way out of whack, this is a 40 and Guzziology calls for a 60...? Not available new
Needle Clip in the middle position.
1/ The V9 Needle and #60 Slide seem to be No Longer Available...
A V5 needle is virtually identical. US Converts came with a 40 slide not 60 (at least every one I've owned and worked on has had a 40.
2/ Guzziology talks about Pumps. This one has no ball in the body, it has the little strainer type thingy and a spring.
No ball inside the little salt shaker looking "plunger"? Could just be stuck. MG Cycle sells the ball.
3/ How does one know which needle valve seat is installed...? Or I guess, more importantly, how is the seat changed...?
On all but the last of the VHBs (and smaller ones) the seat is fixed and can not be changed. Use a Q-Tip coated with toothpaste or fine valve lapping compound, chucked up into a drill, to polish the seat.
4/ Oh, the slide to wall ID is rather significant me thinks but open to verification. The clearance is ~ 0.024" - 0.025" on both the side to side and fore and aft measurement.
Does that mean that the bores are actually worn beyond life lifespan...
Never measured that.
Uhhhg, I am so confused now... In that several components are not available I am not sure just which way to go.
Thanks for putting up with this mess.
Rob
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That's right. One drawback of the kit is the carburetors. They are a bottom of the line version that has no accelerator pumps of either kind, as I recall. It would be nice to hear from someone who has experience having installed this item. The kit is quite cheap, I think.
I replaced my original VHBs with the S-D kit for my 76 t3 about 8 years ago I was very familiar with the PHB carbs from my vespa, they are very simple, like the VHBs, but replacement parts/kits/jets are widely available.
The kit was pretty much plug and play; jetting was very close to spot-on, I didn't have to modify the existing manifolds. The only pain in the keister was the cables; my source for cables is MG Cycle, but they don't carry any cables that work out of the box with the PHB carbs. The problem was that there was "too much" outer cable sheathing to allow me to attach the nipple to the round slide through the carb top; the inner wasn't long enough. So I had to very very carefully use a Dremel cutting wheel to cut off about an inch or so of outer, harder than you might imagine!
I spoke to the MG Cycle guys, and they said that the cable issue is the main reason why they don't stock/carry this kit. They said they had asked S-D what the solution was to the cable issue, and S-D had no solution.
That said, I have run this set-up now for about 10,000 miles and the bike runs great, and the costs was way less than you would pay for a pair of PHMs.
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BSA Nut probably has new VHB slides in 40 and 60 along with V9 needles (if a must have)
Cables for PHF's could be as easy as those fit to beveldrive Ducati's which came with both 30 mm and 32 mm PHF's stock, the catch being, if you are using a twin pull TOMMASELLI throttle . (Two front cylinder cables might work on a Moto Guzzi length wise)
The 900SD had PHF 32's stock (The ones on my Eldorado were the originals off my 900SD Darmah bought in 1983)
That era spigot 32 mm PHF is no longer made so they fetch a premium.
That model has a 1 into 2 cable throttle, maybe the front cylinder cable could work with the Moto Guzzi splitter and its top cable but who knows.
Either way, fully rebuilding VHB's or a custom PHF fitment is going to cost money, time or a combination of both.
Most old needle carburetors will need the needle and needle jet replaced due to wear at some stage.
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Moto Guzzino has V9 (and some other needles). $15 ea: https://guzzino.stores.yahoo.net/vhbne27.html
Crap, I just bought a couple needle valve seats and was going to ask how they are removed and installed. Sure don't want to damage the housing.
Rich A
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I replaced my original VHBs with the S-D kit for my 76 t3 about 8 years ago ...
That said, I have run this set-up now for about 10,000 miles and the bike runs great, and the costs was way less than you would pay for a pair of PHMs.
Thanks for that great report. Making or modifying cables modifying cables is not a big problem. I'll keep this PHBH 30 kit in mind now.
Moto
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I can’t see your vhb’s being worn out
But fitting phbh 30’s is a doddle
On my v700, I used.same manifolds as yours, machined to suit rubber sleeve with a corresponding groove for ridge to sit in. Only things I did to fit was replace studs/ nuts with mushroom head m8’s for clearance and obviously make cables.
Very slight changes to std Lario carbs, flawless starting / running easy 250mile range from the small v700 tank
Only thing I will change is to fit equal length manifolds one day. I’ll use two “D” , the longer of two but anyone chasing more top end might be better off with modified orig v700 ones (equal length and short)
(https://i.ibb.co/4N0nFb5/4-DB186-A7-0-E7-E-4-BD2-86-EF-1-C065020531-B.jpg) (https://ibb.co/4N0nFb5)
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Rob,
Have you looked closely at the needle jets? Mine were hogged out by the needles and result was RICH mixture and poor mileage. IIRC, needles were not worn down but I may have replaced them anyway. Pretty sure I replaced everything else in there so the only thing left was needle jets. When compared to new ones, the difference was obvious to the naked eye. :thumb:
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Sorry, we had unexpected house guests and I am just now getting back to this.
1/ The V9 Needle and #60 Slide seem to be No Longer Available...
A V5 needle is virtually identical. US Converts came with a 40 slide not 60 (at least every one I've owned and worked on has had a 40.
Good to know on the V5 needle. Identical...? So there should not be an issue using the V5...?
2/ Guzziology talks about Pumps. This one has no ball in the body, it has the little strainer type thingy and a spring.
No ball inside the little salt shaker looking "plunger"? Could just be stuck. MG Cycle sells the ball.
To be clear here, this one does not have the ball, just the little salt shaker strainer...is it supposed to have one...?
So I went out to the garage to check on the ball.. I did hear the ball when shaking the salt shaker. When blowing on the canister air will blow through it and when sucking, it stops air flow indicating that the ball is in there.
3/ How does one know which needle valve seat is installed...? Or I guess, more importantly, how is the seat changed...?
On all but the last of the VHBs (and smaller ones) the seat is fixed and can not be changed. Use a Q-Tip coated with toothpaste or fine valve lapping compound, chucked up into a drill, to polish the seat.
Love this idea. Will do just that.
4/ Oh, the slide to wall ID is rather significant me thinks but open to verification. The clearance is ~ 0.024" - 0.025" on both the side to side and fore and aft measurement.
Does that mean that the bores are actually worn beyond life lifespan...
Never measured that.
Thanks for all this Charlie. I appreciate the input.
Rob,
Have you looked closely at the needle jets? Mine were hogged out by the needles and result was RICH mixture and poor mileage. IIRC, needles were not worn down but I may have replaced them anyway. Pretty sure I replaced everything else in there so the only thing left was needle jets. When compared to new ones, the difference was obvious to the naked eye. :thumb:
I have not looked closely to see if they are hogged out but I will, well. I do not know whether those holes are worn or not to be honest. The V9 needles do not appear to be scared to me but I will replace them anyway.
I am going to just throw a bunch of new parts at the carbs, hoping something sticks... lol :grin: My luck, the needle jet body will not be available.
Thank you,
Rob
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Sorry, we had unexpected house guests and I am just now getting back to this.
I have not looked closely to see if they are hogged out but I will, well. I do not know whether those holes are worn or not to be honest. The V9 needles do not appear to be scared to me but I will replace them anyway.
I am going to just throw a bunch of new parts at the carbs, hoping something sticks... lol :grin: My luck, the needle jet body will not be available.
Thank you,
Rob
The difference between the V5 and V9 is so small, one would be very hard pressed to tell them apart in appearance and/or in operation.
https://www.thisoldtractor.com/dellorto_slide_needle_specifications_for__vhb_motorcycle_carburetors_-v_slides-.html
By "needle jet body" do you mean the (265) atomizer? Currently out of stock at MG Cycle:
https://www.mgcycle.com/index.php?main_page=product_info&products_id=2098
Maybe in stock at Harper's or Herdan Corp.?
https://www.harpermoto.com/atomizer-265-for-vhb-13935500.html
https://herdan.com/
In stock at Eurocarb/Dellorto UK:
https://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/carburettor-parts/jets-needles-floats-calibrated-parts/vhb-atomiser-vhbt-27-30mm-cscd/
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I believe that's a steel needle rattling around in a brass jet, so the jet is bound to be the component that suffers. Unless you can actually see something wrong with the needle I would not replace it.
In fact that jet seems to be one of the few components that can really wear in a VHB carburetor. The large flat face of the slide doesn't wear like a round slide does, as Dave Richardson observed. There are no pivots to wear, unlike carbs that have rotating throttle valves. All the other jets just hang around until they get plugged up with gas deposits, but they don't really wear, I think.
Instead of replacing all the jets, the 265 atomizer should be the first choice. Or so it seems to me.
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Greg Bender put together a description of how to re-assemble VHBs: https://www.thisoldtractor.com/moto_guzzi_loopframe_carburetor_rebuild_-__vhb.html
It shows all the pieces/parts very clearly.
Rich A
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Greg also shows this exploded diagram labeling the parts:
(https://www.thisoldtractor.com/mg_images/dellorto_carb_diagram_vhb_guzzi.gif)
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How do you remove the atomizer (needle jet) (part #12). Do you need a special tool or can you just use a drift?
Rich A
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How do you remove the atomizer (needle jet) (part #12). Do you need a special tool or can you just use a drift?
Rich A
No special tool needed. The NJ sticks up above the body just enough so that a brass punch can be used to dislodge it.
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Ahh, now we are getting somewhere. I had Not previously removed the atomizer (doh, smacks forehead) :embarrassed:
@RichA and jwinwi,
I was going to ask the very same question regarding how to remove the #265 Atomizer.
So, I pulled the atomizers out and they do not appear to be worn but what do I know...?
Can someone here tell me the ID of a known, good atomizer #265...? The two that I removed measure ~ 0.118"-ish
Should I replace them...?
Certainly the V9 or V5 Needles should be renewed along with the float needles and polish the seat as per Charlie's recommendation and a complete gasket kit (Which I did do previously when I "Thought" I was "Going through" the carbs. :rolleyes:
This has been a great carb lesson. Now I need to find the parts in the US.
As a side note, I like how Greg mentions Charlie Mullendore in the rebuild article regarding setting the atomizer back into place.
Thanks much all.
Rob
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265 should be 2.65 mm, right? .118" is almost 3 mm. Somebody check my math - I was an English major. :shocked:
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265 should be 2.65 mm, right? .118" is almost 3 mm. Somebody check my math - I was an English major. :shocked:
Ahh, I did not realize that the "265" was indication of the ID.
I'm a little slow and I was not even an English major. :)
So yes, the bore measures ~ 0.301mm. A bit too much huh...?
Thanks,
Rob
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I was wrong about the needle: it's not steel. On the other hand, mine is not much worn, especially compared to the difference just reported in the jet: 2.65 vs. 3.01mm! It's the annular space between the needle and the jet that counts.
I've got the dimensional specs for the V9 needle around somewhere. I'm going to measure my needles before buying new ones.
How did you measure the bore, by the way? Very impressive.
Just ordered two new atomizers.
Moto
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I've got the dimensional specs for the V9 needle around somewhere. I'm going to measure my needles before buying new ones.
I posted a link with the dimensions of all the needles last night:
https://www.thisoldtractor.com/dellorto_slide_needle_specifications_for__vhb_motorcycle_carburetors_-v_slides-.html
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Thanks, Charlie.
It is possible to approximate how much excess flow the needle and needle jet will have with a worn jet.
First, the needle itself is a simple geometric object: a cylinder attached to a truncated cone. The cylindrical part for the V9 needle is 2.48mm in diameter. The needle maintains that diameter down to the point marked "C" in the diagram on the page that Charlie linked to. (It is not immediately clear, but still true, that the diameter given in the table for point A also applies down to point C.) Below that is the truncated cone, which terminates at a diameter of 1.80mm, the point marked "B."
As the Dellorto guide explains, the needle and needle jet combination become important in "high speed" use, which it specifies as about 1/2 throttle. I don't have a carb off my bike so I won't try to measure exactly where on the needle half throttle occurs. (If any one does want to measure that, please do.) I will assume first that half throttle is one half way down the truncated cone. This means the diameter of the needle that regulates fuel flow at half throttle would be half way between the point C and point B diameters, or (2.48 + 1.80) / 2 = 2.14mm. We are interested in how much difference in flow we get at this point when the jet is 3.01mm in diameter instead of the correct 2.65mm.
The flow through the jet should be approximately equal to the cross-sectional area of the jet minus the cross-sectional area of the needle at one-half throttle. This is a ring-shaped, or annular, area. I will calculate it twice, once for a new jet with a 2.65mm diameter, and once for a jet worn to 3.01mm.
A) The annular area for a new jet:
Area = area of the jet minus the area of the needle (at the specified point)
= pi (2.65/2)^2 - pi(2.14/2)^2
= 5.515 - 3.597
= 1.918 mm^2
B) The annular area for a jet worn to 3.01mm:
Area = area of the jet minus the area of the needle (at the specified point)
= pi (3.01/2)^2 - pi(2.14/2)^2
= 7.116 - 3.597
= 3.519 mm^2
C) Ratio of the annular areas, worn versus new:
Ratio = 3.519 / 1.918
= 1.835
So a worn jet of 3.01mm diameter should pass about 83.5% too much fuel at high speeds (half throttle), even with a new needle. This was an eye-opening calculation for me.
I do have a needle removed from one carb. After cleaning it briefly with a Scotchbrite pad I see no signs of wear except some minor denting extending around the circumference about 41mm from the tip, or 15mm into the cylindrical section. I would guess this is the position of the needle that contacts the jet opening at idle. If so, a better calculation for the half-throttle position on the needle might be 3 + 38/2 = 21mm from the tip (allowing for 3mm that never leaves the jet). This would be 21/26 or 81% up the conical part, giving a diameter at half throttle of (.81*2.48 + .19*1.80) = 2.351. Making the same calculations as before, with this new needle diameter, gives the area of the needle at 4.341, and the ratio of the two annular areas (worn vs. new) of (7.116 - 4.341) / (5.515 - 4.341) = 2.364, implying the over-fueling rises by 136% with the worn jet.
I did measure the needle's two specified diameters and found them to be within spec, to the limits of my instrument.
Summary: A worn jet (at 3.01mm diameter) is more than enough to wreak havoc on the fueling at high speeds, increasing it either by 84% or 136%, depending on the assumed position of half-throttle. My own needle is completely smooth in appearance except for marks at 41mm, which I judge to occur when the bike is idling, and which marks are well outside the range of the taper. I concluded that I will probably need a new jet (assuming mine is enlarged) but not a new needle. The calculations were so persuasive that I went ahead and ordered two new 265 atomizers from Harpers before taking off my carburetor!
The needle seems to wear appreciably only at its contact point at idle, which is not relevant to its function. But the same contact at that point ruins the jet.
Moto
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moto,
The measurement for the atomizer bore was not great feat, simply a digital Vernier and accurate enough for this discussion to show that the ID is worn.
What is impressive is the calculation that you posted with a 3.01 mm bore and the effect on fuel consumption. Just Wow...! Indeed quite the eye opener...!
Thanks for that, a good sanity check that my issue Must be in that worn jet. Or in the way that jwinwi stated "Hogged Out"
rad__
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Charlie,
The chart that you linked for needle dims proves your point about the differences between the V9 and V5 needle.
Thanks,
Rob
One other possible issue showed itself when I removed the manifolds from the VHB carbs today getting ready for another ultrasonic bath...
The plastic insulators did not want to let go of the manifold. At all, I finally had to gently vise the carb body with thick cloth buffers on the jaws to twist the manifolds off.
How on Earth will those go back on...? Grease or light oil..? Would that not help break down a plastic, oil based product...? The fit is Very tight.
This concerns me, looking forward to reassembly.
Thanks,
Rob
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Greg also shows this exploded diagram labeling the parts:
(https://www.thisoldtractor.com/mg_images/dellorto_carb_diagram_vhb_guzzi.gif)
moto,
I found one purveyor of the parts I need and while looking through the list-o-stuff for VHB carbs I noticed they have a Mixture Screw Set #17 on this diagram (oddly enough they list as an Idle Screw) WITH an O-Ring and washer...
My carbs (VHB C models) did NOT have the O-ring or the Washer...
This diagram does not list the O-Ring or Washer either.
Thoughts...?
https://guzzino.stores.yahoo.net/idscsephfphm.html
Thanks,
Rob
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17 is what I can an idle mixture screw. 90% of VHBs don't use the o-ring and washer, doesn't seem to make any difference either way.
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Before measuring wear don't you need to know what the manufacturing tolerances were? According to one of my Vespa suppliers (German shop SIP), Dellorto main jets, at least, had pretty large tolerances, they claim "DELLORTO jets can vary up to +/- 0.05mm from the given value".
Not sure if this carries over to other components, or if it is valid for stuff manufactured back in the 70s.
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17 is what I can an idle mixture screw. 90% of VHBs don't use the o-ring and washer, doesn't seem to make any difference either way.
Gotcha,
Thank you,
rad__
Before measuring wear don't you need to know what the manufacturing tolerances were? According to one of my Vespa suppliers (German shop SIP), Dellorto main jets, at least, had pretty large tolerances, they claim "DELLORTO jets can vary up to +/- 0.05mm from the given value".
Not sure if this carries over to other components, or if it is valid for stuff manufactured back in the 70s.
I guess however, the disparity between 2.65mm and 3.01 is huge. The calculation that moto showed us talks directly to the additional amount of fuel consumed when the wear is greater than design diameter.
rad__
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Jet & needle: https://www.ebay.com/itm/183926668299?hash=item2ad2e23c0b:g:rZ0AAMXQ01tRTuYO
Rich A
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Jet & needle: https://www.ebay.com/itm/183926668299?hash=item2ad2e23c0b:g:rZ0AAMXQ01tRTuYO
Rich A
That is a good price for a set. I went with motoguzzino, they had both the V9 Needle and the 265 Atomizers.
As much as I like to stay with the usual suppliers I also like to have a supplier to fall back on.
As with Triumph vendors, I seldom shop around however, often one place will not have everything that I need and instead of making two small orders to two different vendors I will go to the one with all the bits.
I realize also that the V5 needles would have worked as well as the V9 but I just wanted to get the carbs back to stock trim and go from there.
This has been a great learning experience, I appreciate the input from you all.
Update in a week or so...
Best,
Rob
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That is a good price for a set. I went with motoguzzino, they had both the V9 Needle and the 265 Atomizers. ck trim and go from there.
This has been a great learning experience, I appreciate the input from you all.
Update in a week or so...
Best,
Rob
Curiously, you and I seem to be on a parallel track--I'm in the process of refreshing the carbs on my 77 'vert. I think I bought the last set of 265s from MGC, but that was a week ago.
It is a good learning experience--just hope it all works out well.
Rich A
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Before measuring wear don't you need to know what the manufacturing tolerances were? According to one of my Vespa suppliers (German shop SIP), Dellorto main jets, at least, had pretty large tolerances, they claim "DELLORTO jets can vary up to +/- 0.05mm from the given value".
Not sure if this carries over to other components, or if it is valid for stuff manufactured back in the 70s.
I doubt that what you were told is true, or at least was true, since Dellorto made both a 264 and a 265 atomizer, I believe for one of the round slide models. If the tolerance was plus or minus 0.05, that wouldn't have made any sense. For that matter, there are pages and pages of different jet needles for the round slide models, often differing by very small amounts. Again, that would make no sense if tolerances were as sloppy as your shop told you. The production of both the V5 and the v9 needle, previously discussed, is another point against the idea that tolerances were so poor.
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moto,
I found one purveyor of the parts I need and while looking through the list-o-stuff for VHB carbs I noticed they have a Mixture Screw Set #17 on this diagram (oddly enough they list as an Idle Screw) WITH an O-Ring and washer...
My carbs (VHB C models) did NOT have the O-ring or the Washer...
This diagram does not list the O-Ring or Washer either.
Thoughts...?
https://guzzino.stores.yahoo.net/idscsephfphm.html
Thanks,
Rob
The oring sounds like an emissions control modification. I thought maybe I had seen a mention of this in Guzziology but a quick perusal of the chapter turned up nothing. I think Charlie gave you the most important information already.
Moto
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Idle mix screws will WORK with just the screw and a spring, but they COULD leak a bit of air. They are supposed to have a washer and an oring outboard of the spring. The washer I assume is to protect the oring from the sharp edge of the spring, and the oring to prevent air leaks and to hold the whole assembly together during insertion/removal. If the screw comes out without this entire stack, I always go into the hole with a piece of safety wire bent into s short "ell" to hunt for the oring, washer and spring.
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Idle mix screws will WORK with just the screw and a spring, but they COULD leak a bit of air. They are supposed to have a washer and an oring outboard of the spring. The washer I assume is to protect the oring from the sharp edge of the spring, and the oring to prevent air leaks and to hold the whole assembly together during insertion/removal. If the screw comes out without this entire stack, I always go into the hole with a piece of safety wire bent into s short "ell" to hunt for the oring, washer and spring.
That also sounds reasonable. The exploded VHB parts diagram in the V7 Sport parts manual doesn't show the oring and washer, though, so I suppose they must have been added later on:
(https://i.ibb.co/FKQKH80/V7-Sport-Dellorto-parts-diagram.png) (https://ibb.co/FKQKH80)
Moto
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None in the VHBs of: V50 II, Morini 3 1/2, Benelli 650S Tornado, H-D Aermacchi 350 or Benelli 175 Enduro.
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None in the VHBs of: V50 II, Morini 3 1/2, Benelli 650S Tornado, H-D Aermacchi 350 or Benelli 175 Enduro.
You know this stuff better than me. I believe... It works without.
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Curiously, you and I seem to be on a parallel track--I'm in the process of refreshing the carbs on my 77 'vert. I think I bought the last set of 265s from MGC, but that was a week ago.
It is a good learning experience--just hope it all works out well.
Rich A
Great minds and all that Rich... :cool: We do seem to have the same types of rides in the garages, Converts and Hacks. You don't happen to be into Triumphs and MGBs do you...?
So the needles and atomizers are on order, update soon.
Cheers,
Rob
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Great minds and all that Rich... :cool: We do seem to have the same types of rides in the garages, Converts and Hacks. You don't happen to be into Triumphs and MGBs do you...?
So the needles and atomizers are on order, update soon.
Cheers,
Rob
I think we both had early 70s Triumphs (I had a 650 Tiger). As I recall, we both also had mid-60s Yamahas (I had a 250 YDS3). I also had an MGB, sold it a few years ago during a downsizing episode. Kinda weird.
Rich
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UPDATE/REVISION:
It turns out that the OP measured his jet's diameter incorrectly, at the edge of the top surface. The actual aperture is a millimeter or two down in the bore. I didn't recognize this until I received two new atomizers from Harpers and opened my own carb to compare them with a worn atomizer. I could have made the same mistake without the old and new atomizers side by side.
Being down in the bore, the aperture is hard to measure. I tried to pass two drill bits through the new and worn bits. The 3/32 bit (2.38mm) passed through both, but the 7/64 (2.78mm) did not. So my worn bore is less than or equal to 2.78mm. (The new bore is 2.65mm.) I asked the OP to repeat this experiment and he reported the same result.
Now that we know that his bore is not any greater than 2.78mm, I'll repeat my calculation with that figure instead of his initially reported 3.01mm.
I also removed my carb and measured the points on the needle that are level with the bottom of the main bore at idle, half throttle, and full throttle. That is about where the aperture sits inside the atomizer. These are the points I determined on the needle, measuring from its bottom:
41mm -- mark on the needle where it meets the slide, when on the second notch. (Not the jet at idle, as I initially thought.)
36mm -- point on the needle passing through the bottom of the bore at idle (as set recently by me)
26mm -- transition from the cylindrical to the conical part of the needle (as specified in the table)
22mm --- point on the needle passing through the bottom of the bore at half throttle
8mm -- point on the needle passing through the bottom of the bore at full throttle
The travel of the throttle slide from the throttle screw resting position to the point where it leaves the bore at full throttle is 28mm.
From the above I see that the needle is only 4mm into the conical portion at half throttle. Calculating the diameter at that point I get (22/26)*2.48 + (4/26)*1.80 = 2.38mm. So the area of the needle at that point is pi * (2.38/2)^2 = 4.449mm^2. Using that figure with my original formula for the annular areas for a new atomizer and one worn to 2.78mm I get:
A) The annular area for a new jet:
Area = area of the jet minus the area of the needle at 22mm from its bottom:
= pi * (2.65/2)^2 - pi * (2.38/2)^2
= 5.515 - 4.449
= 1.066
B) The annular area for a jet worn to 2.78mm:
Area = area of the jet minus the area of the needle at 22mm from its bottom:
= pi * (2.78/2)^2 - pi * (2.38/2)^2
= 6.070 - 4.449
= 1.621
C_ Ratio of the annular areas, worn versus new:
Ratio = 1.621 / 1.066
= 1.521
So, with the worn jet aperture set to 2.78mm and the position at half throttle identified as 22mm from the bottom of the needle, the degree of over-fueling is about 52%. That's still big, but it is only an upper limit since the actual aperture may be less than 2.78mm.
Using a #36 drill bit could establish an aperture upper limit of 2.71mm, but I don't have that bit.
This calculation is much less interesting without a reliable measurement of the aperture. I regret that I didn't check the value the OP reported before using it.
I gave a half-hearted try at an alternative measurement by timing the flow of a known amount of water through my new and worn atomizer jets, but couldn't detect a difference, probably because my water reservoir was only 60ml.
Moto
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So I received the bits from Moto Guzzino ( www.guzzino.com) today and stuck them in, runs great, a slight popping at idle so I will mess with mixture screws and all that. I had no time for a ride and a plug chop as I had a prior commitment so I'll get to it tomorrow. The two minute running time gave me a sooty plug.
Thinking that just lowering the needle from the stock middle position might be do it but again, I'll test it all out.
On the road to recovery.
rad__
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The measurements I made the other day finally showed me why the needle jet has no effect until nearly half throttle. The tapering part of the needle is still below the aperture until that point, so the needle's taper can have no effect at all until then.
(https://i.ibb.co/nnhvXQD/IMG-20210907-194525893.jpg) (https://ibb.co/nnhvXQD)
So as the Dellorto manual has always said the procedure is to start with the idle mixture, then the pilot jet and cutaway, and only after that the needle and needle jet. The main jet is for the mixture above that. Good luck, and report your success.
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The measurements I made the other day finally showed me why the needle jet has no effect until nearly half throttle. The tapering part of the needle is still below the aperture until that point, so the needle's taper can have no effect at all until then.
So as the Dellorto manual has always said the procedure is to start with the idle mixture, then the pilot jet and cutaway, and only after that the needle and needle jet. The main jet is for the mixture above that. Good luck, and report your success.
Correct, I will start with the idle mixture and go for a test blast. The idle is slightly higher than I recall previously, all the adjusters are bottomed out and there is no issue with the cable routing.
I can get back to the test in a day or so and post the results. I like your term "report your success" :thumb: Will do.
Thanks,
rad__
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Ha! I’m stealing this to make a tshirt.. :thumb:
(https://i.ibb.co/zVGwmD6/4-E3-D0-CE8-9615-4-B75-9824-D26-EE5-E917-EF.gif) (https://ibb.co/zVGwmD6)
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Ha! I’m stealing this to make a tshirt.. :thumb:
(https://i.ibb.co/zVGwmD6/4-E3-D0-CE8-9615-4-B75-9824-D26-EE5-E917-EF.gif) (https://ibb.co/zVGwmD6)
I'll have one in gray, XL, please. :grin:
Moto
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I have not been able to make a good run with the Vert due to a prior commitment yesterday and rainy periods today.
There was a short window for a quick blast of about a mile this early afternoon, the mixture screws were inadvertently set at 1 turn out and not 1-1/2 turns out to start with.
Slight popping was present from idle through about quarter throttle and from there, wow, it pulls so clean and strong, more than I recall previously.
I checked plugs when I got back, not a real plug chop. Not too badly blackened, more dark brown to light-ish black.
As soon as the rain clears up I can do more testing with the 1-1/2 turn setting.
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@moto,
Your previous comments regarding the taper of the needle being still in the aperture discounts Any possibility that making adjustments to the needle would make a significant difference.
Is it your conclusion that a clip change to lower the needle would that not help lean the mixture any at all...?
More later,
Rob
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Chuck,
I'll take a large tee please... :cool:
Thanks,
rad__
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I have not been able to make a good run with the Vert due to a prior commitment yesterday and rainy periods today....
@moto,
Your previous comments regarding the taper of the needle being still in the aperture discounts Any possibility that making adjustments to the needle would make a significant difference.
Is it your conclusion that a clip change to lower the needle would that not help lean the mixture any at all...?
More later,
Rob
Hi Rob,
Lowering the needle will make the mixture leaner, but only in the range above nearly half throttle, where the taper begins to become exposed. (Lowering the needle will also delay the effect of the taper by a small amount since more slide travel will be required to begin to expose the taper.)
Until you reach nearly half throttle, lowering the needle will have no effect at all in making the mixture leaner, since its taper is still concealed below the jet aperture. The taper's effect is constrained to the range above nearly half throttle.
The effect of the tapering part of the needle ends near full throttle when the area of the annular aperture between the needle and jet becomes greater than the area of the main jet (down below, in the float bowl). When that happens, there is no more mixture from the main jet to be passed by increasing the annular area.
The non-tapering, cylindrical part's diameter also affects the mixture before the taper is exposed at nearly half throttle, but lowering the needle does not make the mixture leaner in that range.
This can all be understood by referring to the diagram I posted with the added markings showing where the needle disappears into the jet at 1/4, 1/2, and full throttle, and then comparing those with the marking at 26mm above the needle's tip, which is where the taper starts. Also by reflecting on the admonition of Dellorto to make sure the annular area exceeds the main jet area at full throttle. I don't think I can make a very clear explanation of the diagram without flailing my arms, which doesn't translate into a small amount of text. I'm happy to try to answer specific questions about it.
I think I have this nailed down, but don't forget I'm no specialist. The transitions I just described are simplistic deductions from the positions of the needle and its taper, and from the cross-sectional areas of the main jet and the needle jet annular area. I believe the actual transitions are less precise than this analysis suggests, because of the highly dynamic state of gas flow in the mixing chamber. It's not as precise a science as I make it sound, from what little I've read.
Best,
Moto
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Well I geared up for a test ride of the changes in the Convert carbs, I had planned to burn up an entire tank to see how things had improved, trying to be positive here. :azn:
As headed out the Gen light in the dash came on... Never had previously. Instead of the possibility of being stranded some miles from home I turned back to investigate. The only electrical component that I had touched while playing with the carbs was the Vetter wiring harness connector, simple plug and play however, I checked it. There is no way to connect those two parts incorrectly so I moved on to the headlight, fuses, battery terminals etc... Headlight was inop, both beams.
New H4 bulb installed, I hit the left hand control switch with a Hi beam Flasher / Horn rocker switch, when I hit that the horn weakly sounded and the headlight flashed... odd.
All other lights work as they should, everything, dash lights included so I am thinking that the tin foil innards of the left hand control has finally given it up. :rolleyes:
MGCycle (and others) have a really neat replacement that I like the looks of so I guess that is next.
I was looking forward to a decent ride to test the carb changes but that will have to wait for a bit...
More later, hopefully soon.
rad__
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Well I geared up for a test ride of the changes in the Convert carbs, I had planned to burn up an entire tank to see how things had improved, trying to be positive here. :azn:
As headed out the Gen light in the dash came on... Never had previously. Instead of the possibility of being stranded some miles from home I turned back to investigate. The only electrical component that I had touched while playing with the carbs was the Vetter wiring harness connector, simple plug and play however, I checked it. There is no way to connect those two parts incorrectly so I moved on to the headlight, fuses, battery terminals etc... Headlight was inop, both beams.
New H4 bulb installed, I hit the left hand control switch with a Hi beam Flasher / Horn rocker switch, when I hit that the horn weakly sounded and the headlight flashed... odd.
All other lights work as they should, everything, dash lights included so I am thinking that the tin foil innards of the left hand control has finally given it up. :rolleyes:
MGCycle (and others) have a really neat replacement that I like the looks of so I guess that is next.
I was looking forward to a decent ride to test the carb changes but that will have to wait for a bit...
More later, hopefully soon.
rad__
Sold my (fully functional) original switches for $300 and installed this one:
https://www.mgcycle.com/index.php?main_page=product_info&cPath=37_140&products_id=183
Greg Bender sells a "plug & play" adapter harness for it.
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Sold my (fully functional) original switches for $300 and installed this one:
https://www.mgcycle.com/index.php?main_page=product_info&cPath=37_140&products_id=183
Greg Bender sells a "plug & play" adapter harness for it.
That is the one I have ordered Charlie along with the right hand side, just because. I have installed this very same switch on another Guzzi previously, wicked easy wire up.
I'll have to contact Greg about the plug and play adapter although I have that pesky Vetter harness to deal with so I do not know if that will be a factor or not. :undecided:
Thanks,
Rob
(https://i.ibb.co/92z4Fgb/Left-switch.jpg) (https://ibb.co/92z4Fgb)