Author Topic: PHM40 mysteries and magic  (Read 2946 times)

Offline rusty rotor

  • New Egg
  • *
  • Posts: 21
Re: PHM40 mysteries and magic
« Reply #30 on: September 15, 2021, 08:17:02 PM »
Oh and, can someone recommend a nice straightforward and last-forever carb sync tool?

Offline moto

  • Gaggle Mentor
  • ****
  • *
  • *
  • Posts: 768
  • Potrebbe andare peggio, potrebbe piovere!
  • Location: Madison, WI
Re: PHM40 mysteries and magic
« Reply #31 on: September 15, 2021, 09:18:50 PM »
Thanks for that.
...
Chokes not present on these carbs. Tickle 10x, crank the fast handle 10x, fires right up.
....

You don't need an actual choke. At 70 mph, hold down the tickler(s) That will raise the gas level in the float bowl(s) and richen the mixture. See if the motor runs stronger then, indicating you were too lean. (You can probably get away with doing one tickler if doing both at the same time, at 70 mph, makes you nervous. But doing both would be better. Practice your moves first in your garage.)

It's the same in reverse for the other test. No special tool is needed. Just close the petcock at 70 mph, which will make the mixture leaner as the gas level in the float bowl decreases. If the motor runs stronger when you do this, you were too rich.
« Last Edit: September 15, 2021, 09:25:53 PM by moto »
850 T-3
Griso 1100 corretto
2023 Royal Enfield Classic 350
Italjet Buccaneer 250 (ex-SSR) -- now sold
credit for 2500+ postings lost in the database meltdown of Feb 9, 2020

Offline Scout63

  • Gaggle Hero
  • *****
  • *
  • *
  • *
  • *
  • *
  • Posts: 2677
  • Location: Orleans, MA USA
Re: PHM40 mysteries and magic
« Reply #32 on: September 15, 2021, 09:35:22 PM »
You don't need an actual choke. At 70 mph, hold down the tickler(s) That will raise the gas level in the float bowl(s) and richen the mixture. See if the motor runs stronger then, indicating you were too lean. (You can probably get away with doing one tickler if doing both at the same time, at 70 mph, makes you nervous. But doing both would be better. Practice your moves first in your garage.)

It's the same in reverse for the other test. No special tool is needed. Just close the petcock at 70 mph, which will make the mixture leaner as the gas level in the float bowl decreases. If the motor runs stronger when you do this, you were too rich.

Great advice and very interesting to remember Moto.
Ben Zehnder - Orleans, MA USA

Offline moto

  • Gaggle Mentor
  • ****
  • *
  • *
  • Posts: 768
  • Potrebbe andare peggio, potrebbe piovere!
  • Location: Madison, WI
Re: PHM40 mysteries and magic
« Reply #33 on: September 16, 2021, 04:54:20 PM »
Thanks, Scout.

Another simple thing to try is replacing the inner spark plugs. Charlie said he did not replace them, though he didn't say why. Even if they looked very good, you can never tell about spark plugs and they are cheap enough to replace for diagnostic reasons.
850 T-3
Griso 1100 corretto
2023 Royal Enfield Classic 350
Italjet Buccaneer 250 (ex-SSR) -- now sold
credit for 2500+ postings lost in the database meltdown of Feb 9, 2020

Wildguzzi.com

Re: PHM40 mysteries and magic
« Reply #33 on: September 16, 2021, 04:54:20 PM »

Offline rusty rotor

  • New Egg
  • *
  • Posts: 21
Re: PHM40 mysteries and magic
« Reply #34 on: September 16, 2021, 08:24:01 PM »
I’m imagining myself fumbling for the ticklers at 70mph.

Sounds trickier than my first brassiere, with infinitely worse adverse consequences.

I like and appreciate the advice…how do i deconflict the fact that one side is smoky/sooty, one clean?

Because right now I can easily envision one side is lean and the other rich. Which would confound my result, no?

Offline nc43bsa

  • Gaggle Hero
  • *****
  • *
  • *
  • *
  • *
  • Posts: 1351
  • Location: Mooresville NC
Re: PHM40 mysteries and magic
« Reply #35 on: September 16, 2021, 08:32:05 PM »
First thing I would recommend is to verify the fuel levels in both carbs are the same.  Clear float bowls are the easiest/best way to confirm this.
1990 MilleGT

Offline moto

  • Gaggle Mentor
  • ****
  • *
  • *
  • Posts: 768
  • Potrebbe andare peggio, potrebbe piovere!
  • Location: Madison, WI
Re: PHM40 mysteries and magic
« Reply #36 on: September 16, 2021, 08:57:49 PM »
..
Because right now I can easily envision one side is lean and the other rich. Which would confound my result, no?

It's it's probably better to test each side separately, given the concern you mentioned. You should be able to perceive the result for each side.

Nc43bsa's suggestion is excellent.
850 T-3
Griso 1100 corretto
2023 Royal Enfield Classic 350
Italjet Buccaneer 250 (ex-SSR) -- now sold
credit for 2500+ postings lost in the database meltdown of Feb 9, 2020

Offline berniebee

  • 2020 Board Donor
  • Gaggle Mentor
  • *
  • *
  • *
  • *
  • Posts: 570
  • Location: Ottawa, Canada
Re: PHM40 mysteries and magic
« Reply #37 on: September 16, 2021, 09:19:24 PM »
Thanks for that.

I have checked every spark plug cable, coil wire, fuel line.



The best check for ignition parts is substitution or swapping sides. An incorrect resistance measurement definitely identifies a bad component but unfortunately a correct resistance is not a guarantee of a good part.  Swapping the coils, plugs, caps and wires left to right is easy to do. (Well maybe not the wires...) Sometimes new parts go bad quickly. 

A quick check: Take the carb float off the sooty side and check to see if it has leaked- Ie: shake it, does it have fuel inside?

Offline rusty rotor

  • New Egg
  • *
  • Posts: 21
Re: PHM40 mysteries and magic
« Reply #38 on: September 19, 2021, 02:54:16 PM »

Just got off the bike. Quick reminder, LMI Manfred, big everything. PHM40’s acting up. Or something.

Just as an aside, was behind another bike for miles. You know the type, rear tire that would look at home on a funny car. He was wearing all the gear, all the HD-branded gear.
And sandals. Hey at least they weren’t flip flops.

Speaking of ignorant, I went ahead and started to futz with the carbs today.

First I baselined and took notes.

Before I get into all that, a couple of observations:

The right side carb spews gas when you tickle it aggressively. Sometimes. I didn’t know this was happening as I tickle hunched over on the left side, it just happened today that my hand got spattered with fuel. Squirt squirt squirt from a tiny port above the tickler. What’s that mean? Left side dry.

The right side double banjo may not be seeing full flow. I looked down while stopped at a light and happened to be watching as a big glug of gas moved through the back hose.

The left side petcock may not be delivering fuel adequately as the left side filter is only sometimes full of fuel. The right side seems fine. Both brand new.

So, baselines:

Idle mix screw
RH out 2.25
LH out 2.20

Today I turned each one out one full turn. This upped idle speed to about 1100. Why? Why the hell not.

Rode the bike, and it seemed noticeably better, though a little rough and sputtery on steady throttle or just off throttle, mainly on the right side.

Pulled over, set the petcocks to reserve in case there’s a blockage that might help with. Didn’t see any difference in fuel flow.

Baselined the idle speed adjuster screw. 

RH was 5 turns out
LH was 5.5 turns out

Turned the left side out 1/2 turn. Why? Because it’s there.

That took the idle up to 1400 fully hot, but the bike ran better.

Still seeing intermittent less severe bogging when cracking the slides hard, but then it grabs and goes hard.

Oh and I seem to have made the detonation in the left side worse. It still takes a handful of throttle to produce it, but it seems louder and more aggressive. It’s pretty bad so I back off right away. Sigh. Better get the tool to do a leak-down test.

In case it's the floats, are there any NOS floats out there somewhere?

One of the vendors of transparent float bowls states to never install them permanently. That accurate? They only a diagnostic tool?

Where do I go from here?


Offline rusty rotor

  • New Egg
  • *
  • Posts: 21
Re: PHM40 mysteries and magic
« Reply #39 on: September 19, 2021, 03:16:06 PM »
Oh and, temperatures are a solid 15-20F lower than they have been. Just to make things more interesting.

Online John A

  • Gaggle Hero
  • *****
  • *
  • *
  • *
  • *
  • Posts: 4896
  • No way to slow down...
  • Location: Hager city ,western WI
Re: PHM40 mysteries and magic
« Reply #40 on: September 19, 2021, 09:56:37 PM »
Oh and, temperatures are a solid 15-20F lower than they have been. Just to make things more interesting.




Yep, an engine that’s stepped on is more sensitive to ambient conditions.  That’s what makes it interesting sometimes
John
MGNOC L-471
It is easier to fool people than it is to convince them that they have been fooled-Mark Twain
99 Bassa, sidecar
02 Stone
84 V65C
15 F3S Spyder

Offline nc43bsa

  • Gaggle Hero
  • *****
  • *
  • *
  • *
  • *
  • Posts: 1351
  • Location: Mooresville NC
Re: PHM40 mysteries and magic
« Reply #41 on: September 19, 2021, 10:54:04 PM »
Before I get into all that, a couple of observations:

The right side carb spews gas when you tickle it aggressively. Sometimes. I didn’t know this was happening as I tickle hunched over on the left side, it just happened today that my hand got spattered with fuel. Squirt squirt squirt from a tiny port above the tickler. What’s that mean? Left side dry.

Keep in mind what the tickler does;  it pushes the float down to allow more fuel into the bowl than the float would by itself.

So, if using the right tickler produces a gush of fuel out of the bleed hole and using the left tickler does not, what does that mean?  It means the fuel level in the right carb is higher than the level in the left carb, BEFORE the tickler is used.

Until you verify the correct fuel levels in both carbs, you'll be chasing your tail 'til the cows come home.

<edit>  I went back and read the original post: "Right pipe a little smoky, right tip a little sooty, left side clean."

Another indication the right fuel level is higher than the left.  Higher fuel level = richer mixture
« Last Edit: September 19, 2021, 11:31:53 PM by nc43bsa »
1990 MilleGT

Offline moto

  • Gaggle Mentor
  • ****
  • *
  • *
  • Posts: 768
  • Potrebbe andare peggio, potrebbe piovere!
  • Location: Madison, WI
Re: PHM40 mysteries and magic
« Reply #42 on: September 19, 2021, 11:48:14 PM »
Keep in mind what the tickler does;  it pushes the float down to allow more fuel into the bowl than the float would by itself.

So, if using the right tickler produces a gush of fuel out of the bleed hole and using the left tickler does not, what does that mean?  It means the fuel level in the right carb is higher than the level in the left carb, BEFORE the tickler is used.

Until you verify the correct fuel levels in both carbs, you'll be chasing your tail 'til the cows come home.

<edit>  I went back and read the original post: "Right pipe a little smoky, right tip a little sooty, left side clean."

Another indication the right fuel level is higher than the left.  Higher fuel level = richer mixture

As you pursue nc43bsa's excellent deduction, remember there are two ways the right bowl can have a higher fuel level: mis-adjustment  of the tab on the lever; or one of the floats in the right carburetor may be full or nearly full of gas, causing it to float lower in the gas pool and so allowing the gas level in the bowl to rise. My bet is the latter. You can check for this by shaking the floats, after removing them. You can also use sensitive scales to compare the total weight of the right carburetor floats with that of the left ones.

Of course if you have the transparent float bowls, you can compare the levels directly.

EDIT: Here is the document showing how to set the floats on your PHM carburetors: https://www.thisoldtractor.com/dellorto_setting_the_float_height_on__carburetors.html
« Last Edit: September 19, 2021, 11:53:48 PM by moto »
850 T-3
Griso 1100 corretto
2023 Royal Enfield Classic 350
Italjet Buccaneer 250 (ex-SSR) -- now sold
credit for 2500+ postings lost in the database meltdown of Feb 9, 2020

Offline rusty rotor

  • New Egg
  • *
  • Posts: 21
Re: PHM40 mysteries and magic
« Reply #43 on: September 20, 2021, 01:02:19 PM »
You guys rock. Thank you for the help.

I'll be working on those floats.

I've found Dellorto brand black plastic floats for PHM40. It is the white ones that suck, yes? New black ones all good?

Also, have I said anything here that indicates the floats may not be the right weight (is it weight, flotation?)? I ask as the vendor lists four weights.

I never really appreciated how well-carbureted this bike was, till now.
« Last Edit: September 20, 2021, 01:04:06 PM by rusty rotor »

Offline moto

  • Gaggle Mentor
  • ****
  • *
  • *
  • Posts: 768
  • Potrebbe andare peggio, potrebbe piovere!
  • Location: Madison, WI
Re: PHM40 mysteries and magic
« Reply #44 on: September 20, 2021, 01:57:26 PM »
It has been said for many years that Dellorto black floats are no longer being manufactured. Sometimes vendors show products on their websites that are not available. You might want to confirm availability before ordering. If you do find new Dellorto black floats please let us know where, after satisfying your need.

I don't know the proper float weight specification for your carburetors. You can read the weight in grams on your current floats, cast into the plastic. I'd go with that, but only after having confirmed there is a weight discrepancy in your current set of floats.

Since the float height specification is given as a physical measurement of the float as it sits in the empty carburetor body, there is no allowance for an incorrect float weight. Floats that are too light or too heavy will sit incorrectly on top of the pool of gasoline, too high or too low, causing leanness or richness, respectively.

EDIT: It is just conceivable that the manufactured weights of the floats in the two carburetors differ, with the right one heavier. Easy to check. Nearly unimaginable, though, given who worked on it.
« Last Edit: September 20, 2021, 03:47:08 PM by moto »
850 T-3
Griso 1100 corretto
2023 Royal Enfield Classic 350
Italjet Buccaneer 250 (ex-SSR) -- now sold
credit for 2500+ postings lost in the database meltdown of Feb 9, 2020

Online Antietam Classic Cycle

  • Gaggle Hero
  • *****
  • *
  • Posts: 14123
  • Happily stuck in the past.
    • Antietam Classic Cycle
  • Location: Rohrersville, Maryland
Re: PHM40 mysteries and magic
« Reply #45 on: September 20, 2021, 04:13:53 PM »
The white floats are all 8.5 grams.
Charlie

Offline moto

  • Gaggle Mentor
  • ****
  • *
  • *
  • Posts: 768
  • Potrebbe andare peggio, potrebbe piovere!
  • Location: Madison, WI
Re: PHM40 mysteries and magic
« Reply #46 on: September 20, 2021, 08:59:26 PM »
The white floats are all 8.5 grams.

I believe it. It's all I've seen.

The original float weight specifications are a mystery to me. The T3 and other contemporary Tonti's had 10 gram floats, per the Haynes manual. The factory workshop manual agrees. Mine still has the originals, I guess, in a dark olive color.

The Haynes manual, using the T3 as its subject, gives separate height specifications, 1mm apart, for the 10g and 14g floats. As makes sense, the 14g floats are set to run deeper in the bowl (a greater measured height specification).

The Dellorto Guide says its floats:

"are usually available with two different weights:
   • a light float to obtain a low level (for two-stroke engines)
   • a heavy float to produce a higher level (for four stroke engines)"

EDIT: Note the implication here is that the light or heavy float would be used with the same height specifications, contrary to the practice illustrated in the Haynes manual, where two different-weight floats could be substituted for each other by changing the height.

I don't know if the 8.5g float now available in white would have been intended for two-stroke engines, since it is lighter than the 10g stock unit in the T3. (The V700 had a 14g float, per either the Chilton or the Haynes manual.)

I conclude that using a lighter-than-original 8.5g float would produce a somewhat lean mixture across a lot of the throttle range, maybe mostly toward the lower end. Probably this would be compensated for (if at all) by using larger pilot jets or raising the needle. Alternatively, the float height specification could be decreased, to let them run higher in the gas pool. Maybe by less than 1mm.

As for the original poster's problem, of course, the main thing he should work on now is to make sure both sides are the same.
« Last Edit: September 21, 2021, 12:46:42 AM by moto »
850 T-3
Griso 1100 corretto
2023 Royal Enfield Classic 350
Italjet Buccaneer 250 (ex-SSR) -- now sold
credit for 2500+ postings lost in the database meltdown of Feb 9, 2020

Online Antietam Classic Cycle

  • Gaggle Hero
  • *****
  • *
  • Posts: 14123
  • Happily stuck in the past.
    • Antietam Classic Cycle
  • Location: Rohrersville, Maryland
Re: PHM40 mysteries and magic
« Reply #47 on: September 20, 2021, 10:13:06 PM »
I believe it. It's all I've seen.

Seems they are available in 10 gram and heavier as well - just saw some on Stein-Dinse. Still crappy white floats though...
Charlie

Offline rusty rotor

  • New Egg
  • *
  • Posts: 21
Re: PHM40 mysteries and magic
« Reply #48 on: September 21, 2021, 09:25:24 AM »
Acquired Dellorto manuals and sync tool.

Am likely to shotgun the floats, something’s up w them.

$200 for floats!? Ouch.

Offline moto

  • Gaggle Mentor
  • ****
  • *
  • *
  • Posts: 768
  • Potrebbe andare peggio, potrebbe piovere!
  • Location: Madison, WI
Re: PHM40 mysteries and magic
« Reply #49 on: September 21, 2021, 11:37:34 AM »
This is general information about the floats (same for the PHM and the VHB), from DellortoShop.com:

Quote
This is the double float for the Dellorto PHM carburetors.

Originally, these came only in the early style, black, style with metal linking arm but these have been phased out in favor of the, new, white version.

Please choose the replacement for your defective float according to the part-number on your original.

Available in the following versions:

7450.1 8.5 gram white - replaces 7450.1 10 gram black
7450.2 12.5 gram white - replaces 7450.2 14 gram black - Sold out at the moment
You can order this size but the delivery time is unknown at this moment
7450.3 6,5 gram white - replaces 7450.3 7.5 gram black
Required quantity per carburetor: 1
...
Dellorto Part Number: 7450

So there were originally weights of 7.5, 10, and 14 grams in the "black" model, each replaced by a lighter version -- 6.5, 8.5, and 12.5, respectively -- in the white version (according to the site, at least).

Why the change in weights? It couldn't have been to make all the carburetors run leaner. Instead, it must be that the center of mass of the original floats with their brass linking arms is closer to the pivot, so the effective weights of the original and newly-recommended replacements are approximately the same.

The OP should try to determine the original float weight for his PHMs and proceed accordingly.

Moto

P.S. Stein-Dinse lists the same white floats of 6.5, 8.5 and 12.5 grams as found at DellortoShop.com.
« Last Edit: September 21, 2021, 11:42:59 AM by moto »
850 T-3
Griso 1100 corretto
2023 Royal Enfield Classic 350
Italjet Buccaneer 250 (ex-SSR) -- now sold
credit for 2500+ postings lost in the database meltdown of Feb 9, 2020

Offline rusty rotor

  • New Egg
  • *
  • Posts: 21
Re: PHM40 mysteries and magic
« Reply #50 on: September 21, 2021, 02:51:43 PM »
My Dellorto shop states unequivocally that the white float failure thing is not just overblown but vastly so.

He tells me failures exist but are very much the exception not the rule.

« Last Edit: September 21, 2021, 02:59:00 PM by rusty rotor »

jwinwi

  • Guest
Re: PHM40 mysteries and magic
« Reply #51 on: September 21, 2021, 03:06:04 PM »
My Dellorto shop states unequivocally that the white float failure thing is not just overblown but vastly so.

He tells me failures exist but are very much the exception not the rule.

 :popcorn:

Offline rusty rotor

  • New Egg
  • *
  • Posts: 21
Re: PHM40 mysteries and magic
« Reply #52 on: September 21, 2021, 08:41:18 PM »
Do go on

Offline Kiwi_Roy

  • Gaggle Hero
  • *****
  • Posts: 9796
  • Location: New Westminster BC
Re: PHM40 mysteries and magic
« Reply #53 on: September 21, 2021, 10:22:32 PM »

Now the bike seems to fairly quickly detuning itself. Starting to run rougher, and bogging pretty strongly when you smack open the slides. Smooth and gentle inputs all the time result in 99.9% smooth running. What fun is that!
Right pipe a little smoky, right tip a little sooty, left side clean.

Weirdly, this bogging on acceleration seems to be intermittent. I can't reproduce it every time.
 
I have an electrical background so I always blame electrical first, weak spark can cause bogging as you open the throttle the denser air in the cylinder makes it harder for the spark to jump the gaps. here's a simple test you can do
Measure the resistance  from cap to cap each side, this will be the sum of caps, leads and coil. of the coils.
Compare one side against the other, since you have twin plugs it will be from one plug cap to the other plug cap. I'm guessing about 8,000 Ohms each side. Do you have resistor caps, you shouldn't have resistor leads. What plugs do you have, they shouldn't have an R in the part number if you have resistor caps
If you notice any difference side to side please post all the component part numbers.
Plug
Coil
Caps
I hope you didn't replace the condensers during the refresh process, the condenser is a critical part of producing a spark and modern condensers are CRAP, you are better off with a 40 year old one when they knew how to make them properly, yours should be engraved with a decent manufacturers name, not some generic M.I.C.
« Last Edit: September 21, 2021, 10:30:46 PM by Kiwi_Roy »
72 Eldorado
17 V7iii Special
76 Convert
Half a V9 Roamer

Moto Guzzi - making electricians out of riders since March 15 1921

Online Antietam Classic Cycle

  • Gaggle Hero
  • *****
  • *
  • Posts: 14123
  • Happily stuck in the past.
    • Antietam Classic Cycle
  • Location: Rohrersville, Maryland
Re: PHM40 mysteries and magic
« Reply #54 on: September 22, 2021, 08:39:42 AM »
I have an electrical background so I always blame electrical first, weak spark can cause bogging as you open the throttle the denser air in the cylinder makes it harder for the spark to jump the gaps. here's a simple test you can do
Measure the resistance  from cap to cap each side, this will be the sum of caps, leads and coil. of the coils.
Compare one side against the other, since you have twin plugs it will be from one plug cap to the other plug cap. I'm guessing about 8,000 Ohms each side. Do you have resistor caps, you shouldn't have resistor leads. What plugs do you have, they shouldn't have an R in the part number if you have resistor caps
If you notice any difference side to side please post all the component part numbers.
Plug
Coil
Caps
I hope you didn't replace the condensers during the refresh process, the condenser is a critical part of producing a spark and modern condensers are CRAP, you are better off with a 40 year old one when they knew how to make them properly, yours should be engraved with a decent manufacturers name, not some generic M.I.C.

It has solid-core Belden leads, NGK resistor caps and non-resistor plugs, (new) Dyna III ignition and green coils.
Charlie

Offline pressureangle

  • Gaggle Mentor
  • ****
  • *
  • *
  • *
  • *
  • *
  • Posts: 972
  • '97 1100 Sport i, '89 Mille GT
Re: PHM40 mysteries and magic
« Reply #55 on: September 22, 2021, 10:30:26 AM »
So who has checked the charging voltage?

My LM1000 had all these precise symptoms- when the battery ran down a bit. Between a good headlight and the dyna ignition, the charging system was too weak to keep up. I put a Euromotoelectric system on it and everything became shiny.
Something wistful and amusing, yet poignant.

Offline rusty rotor

  • New Egg
  • *
  • Posts: 21
Re: PHM40 mysteries and magic
« Reply #56 on: September 22, 2021, 04:01:48 PM »
That’s actually a fascinating idea. I dont understand how it would work, but interesting anyway.

Plus the battery is always nice and strong, however unscientific that is.

Online Antietam Classic Cycle

  • Gaggle Hero
  • *****
  • *
  • Posts: 14123
  • Happily stuck in the past.
    • Antietam Classic Cycle
  • Location: Rohrersville, Maryland
Re: PHM40 mysteries and magic
« Reply #57 on: September 22, 2021, 05:51:20 PM »
So who has checked the charging voltage?

My LM1000 had all these precise symptoms- when the battery ran down a bit. Between a good headlight and the dyna ignition, the charging system was too weak to keep up. I put a Euromotoelectric system on it and everything became shiny.

Rusty's Le Mans has a new (ETX30L) battery, solid state voltage regulator and Grote LED headlight (and taillight, signals, gauge illumination bulbs and warning light). Charging output was checked and output was 14.2 max.
Charlie

***Wildguzzi Official Logo High Quality 5 Color Window Decals Back In Stock***
Shipping in USA Only. Awesome quality. Back by popular demand. All proceeds go back into the forum.
http://www.wildguzzi.com/Products/products.htm
Advertise Here
 

Quad Lock - The best GPS / phone mount system for your motorcycles, no damage to your cameras!!
Get a Wildguzzi discount of 10% off your order!
http://quadlock.refr.cc/luapmckeever
Advertise Here