Author Topic: Carburation improvements for an Eldorado 850  (Read 6070 times)

canuck750

  • Guest
Carburation improvements for an Eldorado 850
« on: November 01, 2015, 07:20:17 PM »
I have a pair of rebuilt VHB 29 carbs on my Eldorado 850 and have cleaned them in an ultrasonic cleaner and fitted all new internals including replacing the slides. The bike was set up on a dyno and jetted to suit. The bike runs pretty good at sustained speed but it does not like to run in stop and go in the city. Once warmed up when coming to a stop at a light in neutral the rpm will rise from just over 1000 rpm to over 2500 rpm. I have to hold in the clutch and shift into 1st and slightly release the clutch to load up the engine to bring the rpm down. I enjoy riding the Eldorado but have gotten tired of the VHB's not working as I would expect.

I am thinking the VHB's are perhaps just too tired out??

I have a pair of PHF 30's that came off a 850T that have been rebuilt and I found a pair of Mikuni carbs at a swap meet today that came of a 850 Norton Commando.

Looking for advice on a suitable replacement that will hopefully give good performance and a smooth and consistent idle.

Thanks

Jim

Offline Cam3512

  • Gaggle Hero
  • *****
  • *
  • Posts: 6517
Re: Carburation improvements for an Eldorado 850
« Reply #1 on: November 01, 2015, 07:29:47 PM »
Just guessing here, but do your throttle cables have enough freeplay?  I had to remove the locknut on the carb adjusters to get it right.  VHB's have been nothing but good to me on my 2 Eldos, 1 Ambo, and my Sport (30's).

OR, do you have the light springs installed?  At idle, they wouldn't return the slides well enough on mine.  Few years ago I found a few pairs of "medium" weight springs (in England) and that was the ticket.  Apparently MG Cycle now repros them - They were once unobtanium.  Charlie put a pair in my Ambo.
« Last Edit: November 01, 2015, 07:35:32 PM by Cam3512 »
Cam in NJ
'67 Stornello Scrambler
'71 Ambo Police
'74 V7 Sport
20 V85TT

http://mgnocnj.forumotion.com

canuck750

  • Guest
Re: Carburation improvements for an Eldorado 850
« Reply #2 on: November 01, 2015, 07:41:19 PM »
The shop that ran my Eldorado on their dyno complained that the left cable was just too short so they made new ones (these were new replacements from MG Cycle). I replaced the cable operated chokes with flip levers. I also found that the new replacement idle needle tension springs were one coil too long and prevented the idle needles from turning in far enough to raise the slides. I cut down the idle needle springs and I was able to adjust the slide height.

My V7 Sport VHB 30's perform pretty good but I don't think I have the Sport dialed in as good as I could get it. At least the Sport does not have the rapidly climbing idle problem and the idle is pretty good.

My Eldorado has an electronic ignition from Harper's and the fully rebuilt motor now has about 2500 miles on it.

I synced the carbs with carb sticks and set the timing with a stobe light this fall.

Offline JoeW

  • Gaggle Hero
  • *****
  • *
  • Posts: 2479
    • The Guzzi Doctor
Re: Carburation improvements for an Eldorado 850
« Reply #3 on: November 01, 2015, 08:14:15 PM »
Jim, it sounds to me like you're idling off the main jet. I would look at the slides and how far they are being held open by the idle speed screw. I think you either have slides that have been modified or the idle circuit is not flowing properly. When I set up curbs, I back out the idle speed screw 1/8 turn at a time and adjust the mixture screw until I get the best possible idle with the slide open as little as possible. Also, make sure there is free play in the cables. The other possibility is, someone may have "cooked" or shortened the return springs trying to reduce throttle effort.
Joe Walano

Wildguzzi.com

Re: Carburation improvements for an Eldorado 850
« Reply #3 on: November 01, 2015, 08:14:15 PM »

canuck750

  • Guest
Re: Carburation improvements for an Eldorado 850
« Reply #4 on: November 01, 2015, 09:38:23 PM »
Thanks Joe

I will take another look

Jim

Offline mtiberio

  • Gaggle Hero
  • *****
  • Posts: 4218
    • TiberioRacing
Re: Carburation improvements for an Eldorado 850
« Reply #5 on: November 02, 2015, 06:08:59 AM »
valves too tight?
Land Speed Records w/Guzzzi:
SCTA M-PG 1000 141.6 MPH
LTA M-PF 1000 137.3 MPH
ECTA M-PG 1000 118.6 MPH
http://gjm.site90.com/mtiberio

Offline EldoMike

  • Gaggle Mentor
  • ****
  • *
  • *
  • *
  • *
  • Posts: 814
  • Location: Southern Illinois
Re: Carburation improvements for an Eldorado 850
« Reply #6 on: November 02, 2015, 06:20:10 AM »
Timing staying advanced?

Online nick949

  • All you have to do is decide what to do with the time that's given to you.
  • Gaggle Hero
  • *****
  • Posts: 3159
    • Nick Adams Writing
Re: Carburation improvements for an Eldorado 850
« Reply #7 on: November 02, 2015, 06:42:38 AM »

I synced the carbs with carb sticks and set the timing with a stobe light this fall.

That's the problem Jim - far too high tech.   :evil:  Do it by ear and it will work out fine. :boozing:

Nick

Offline leafman60

  • Gaggle Hero
  • *****
  • *
  • *
  • Posts: 6984
Re: Carburation improvements for an Eldorado 850
« Reply #8 on: November 02, 2015, 06:53:44 AM »
My 850 had the stock carbs, well tuned, and they worked like a charm. Great idle, great linear acceleration and smooth cruising. If you are having trouble, something is out of place.

Please don't install a pair of Japanese mikunis on that thing!

Offline guzziownr

  • Gaggle Hero
  • *****
  • Posts: 2122
Re: Carburation improvements for an Eldorado 850
« Reply #9 on: November 02, 2015, 07:02:58 AM »
Please don't install a pair of Japanese mikunis on that thing!

I think you mean the Chinese copies of the Japanese knock-offs of the British Amal carbs  :grin:

I found the stockers great in the city commute.  Non-stock, worn out, or hanging up slides would be my guess as well.
If you ever feel like no one pays attention to you, try making a sandwich in front of your dog

Offline leafman60

  • Gaggle Hero
  • *****
  • *
  • *
  • Posts: 6984
Re: Carburation improvements for an Eldorado 850
« Reply #10 on: November 02, 2015, 07:06:34 AM »
I think you mean the Chinese copies of the Japanese knock-offs of the British Amal carbs  :grin:

LOL


Offline mtiberio

  • Gaggle Hero
  • *****
  • Posts: 4218
    • TiberioRacing
Re: Carburation improvements for an Eldorado 850
« Reply #11 on: November 02, 2015, 07:56:22 AM »
I like my "Chinese copies of the Japanese knock-offs of the British Amal carbs". The throttle is lighter than some FI bikes... Can't say that about VHBs
Land Speed Records w/Guzzzi:
SCTA M-PG 1000 141.6 MPH
LTA M-PF 1000 137.3 MPH
ECTA M-PG 1000 118.6 MPH
http://gjm.site90.com/mtiberio

Offline Rich A

  • Gaggle Hero
  • *****
  • *
  • *
  • *
  • *
  • Posts: 3151
Re: Carburation improvements for an Eldorado 850
« Reply #12 on: November 02, 2015, 08:14:40 AM »
I'd had two loops and neither had any problems with idling even at 6-7000 ft. As they say, your carb problems could be electrical (you didn't mention the coil). Or the valves may need to be properly set. And sometimes the carbs' slides get installed backwards.

I did have a problem with a Honda (CBF 400) that didn't idle at my elevation because the idle jets were too big. What's your elevation?

Rich A

Offline Groover

  • 2019 Board Donor
  • Gaggle Hero
  • *
  • *
  • Posts: 2838
  • If it ain't broke, I'll break it.
    • Scooteropolis
  • Location: Columbus, Ohio
Re: Carburation improvements for an Eldorado 850
« Reply #13 on: November 02, 2015, 08:30:01 AM »
It also sounds to me the low end needles need backed out maybe 1/4 of a turn. Not sure how that electronic ignition you have is configured, but I had a similar issue last season where my idle would raise when at idle too long, or simply the duration of a red light. Turned out to be in my case the aftermarket wax-filled coils were faulty and they would get too hot at low speed, I think causing the spark to be hotter when that would happen thus making the low end mixture lean; at least that was my conclusion.

I ended up changing the coils with older OEM oil-filled Magnetti Marelli coils, backed out the low end needed 1/4 turn on both carbs, and that problem is gone. Not sure which one fixed the creeping-idle issue, but a combination of both did. No other items were changed. So based on my case, I would suggest you take a look at those two items.

Good luck.

1981 Moto Guzzi V1000G5
1987 Moto Guzzi LM1000SE, a
1987 Moto Guzzi LM1000SE, b
1980 Piaggio Vespa P200E
1980 Piaggio Vespa P125X
1980 Vespa Grande Moped
1980 Vespa SI Moped
http://scooteropolis.com/

Offline acogoff

  • Gaggle Hero
  • *****
  • *
  • *
  • *
  • *
  • *
  • Posts: 1203
Re: Carburation improvements for an Eldorado 850
« Reply #14 on: November 02, 2015, 09:26:16 AM »
    Sounds like you have an air leak in your intake if the rpm is rising on its own in neutral. I had that problem and found that the aftermarket green intake gaskets 14115500 are not up to the task and found the installed the originals. Problem solved.
'77850t3FB Owned since it was new
Marshall County Minnesota USA

Offline Mike Harper

  • Gaggle Hero
  • *****
  • *
  • Posts: 1701
    • harpermoto.com
  • Location: Greenwood/Lone Jack MO
Re: Carburation improvements for an Eldorado 850
« Reply #15 on: November 02, 2015, 09:39:59 AM »
I have a pair of rebuilt VHB 29 carbs on my Eldorado 850 and have cleaned them in an ultrasonic cleaner and fitted all new internals including replacing the slides. The bike was set up on a dyno and jetted to suit. The bike runs pretty good at sustained speed but it does not like to run in stop and go in the city. Once warmed up when coming to a stop at a light in neutral the rpm will rise from just over 1000 rpm to over 2500 rpm. I have to hold in the clutch and shift into 1st and slightly release the clutch to load up the engine to bring the rpm down. I enjoy riding the Eldorado but have gotten tired of the VHB's not working as I would expect.

I am thinking the VHB's are perhaps just too tired out??









I have a pair of PHF 30's that came off a 850T that have been rebuilt and I found a pair of Mikuni carbs at a swap meet today that came of a 850 Norton Commando.

Looking for advice on a suitable replacement that will hopefully give good performance and a smooth and consistent idle.

Thanks

Jim


It seems to me that whomever did the Super Duper Dyno tune on your Eldo may well be the culprit here.  If all the basics are not correct before hand I don't understand how in the %$#$#% you can Dyno tune anything.  If the bike is not running properly then all tuning efforts are moot. Find the cause of the problem first, get the bike running and idling correctly before trying any final tuning.  Basics first.

Just My 2 cents
« Last Edit: November 02, 2015, 10:25:32 AM by Mike Harper »

nunzio

  • Guest
Re: Carburation improvements for an Eldorado 850
« Reply #16 on: November 02, 2015, 01:14:30 PM »

" I replaced the cable operated chokes with flip levers."

Choke problem?......Alan

canuck750

  • Guest
Re: Carburation improvements for an Eldorado 850
« Reply #17 on: November 02, 2015, 01:37:32 PM »

It seems to me that whomever did the Super Duper Dyno tune on your Eldo may well be the culprit here.  If all the basics are not correct before hand I don't understand how in the %$#$#% you can Dyno tune anything.  If the bike is not running properly then all tuning efforts are moot. Find the cause of the problem first, get the bike running and idling correctly before trying any final tuning.  Basics first.

Just My 2 cents

Yes I agree, the bike was set up real good before I dropped it off, I was smitten by a dyno session having never treated a bike to one before. Before I dropped the bike off I set the valves, strobed the timing, new plugs and on and on. Before I took the bike in I had the idle climbing trouble and was hoping a 'pro' could get it fixed for me.

They swapped out jets, played with the idle and mixture and pronounced it perfect. As soon as it warmed up the idle problem returned. I got the bike to run a lot better by following Greg Bender's instructions for carb tuning but the idle problem persists. I rode the V7 Sport most of the summer and put the Eldo on the back burner. This winter I want to get the running issues solved once and for all.

I know I am just a hack with a set of tools but I keep thinking I could have done better by not consulting the local 'pros' (who really only understand Japanese multi cylinder bikes) and trust in the force er, Wild Guzzi brain trust.

It's always something simple but it gets tiring sometimes to not know how to solve what should be a minor issue.

Thanks for all the help, much appreciated.

Online nick949

  • All you have to do is decide what to do with the time that's given to you.
  • Gaggle Hero
  • *****
  • Posts: 3159
    • Nick Adams Writing
Re: Carburation improvements for an Eldorado 850
« Reply #18 on: November 02, 2015, 02:08:16 PM »

I know I am just a hack with a set of tools ....

Yea - right!  ROFL

Nick

Offline twhitaker

  • Gaggle Hero
  • *****
  • Posts: 8323
Re: Carburation improvements for an Eldorado 850
« Reply #19 on: November 02, 2015, 05:11:20 PM »
Quote
They swapped out jets, played with the idle and mixture and pronounced it perfect.

I certainly hope you put the 'right' ones back in?
'96 California 1100i 160,000 mi
'97 Centauro yellow 25,000 mi
'02 Champagne V11 LeMans 58,000 mi
MGNOC-11168
Dayton, OH

Offline 80CX100

  • Gaggle Hero
  • *****
  • *
  • *
  • *
  • *
  • *
  • Posts: 1421
  • Location: Ontario, Canada
Re: Carburation improvements for an Eldorado 850
« Reply #20 on: November 02, 2015, 05:18:37 PM »
I have a pair of rebuilt VHB 29 carbs on my Eldorado 850 and have cleaned them in an ultrasonic cleaner and fitted all new internals including replacing the slides. The bike was set up on a dyno and jetted to suit. The bike runs pretty good at sustained speed but it does not like to run in stop and go in the city. Once warmed up when coming to a stop at a light in neutral the rpm will rise from just over 1000 rpm to over 2500 rpm. I have to hold in the clutch and shift into 1st and slightly release the clutch to load up the engine to bring the rpm down. I enjoy riding the Eldorado but have gotten tired of the VHB's not working as I would expect.

I am thinking the VHB's are perhaps just too tired out??

I have a pair of PHF 30's that came off a 850T that have been rebuilt and I found a pair of Mikuni carbs at a swap meet today that came of a 850 Norton Commando.

Looking for advice on a suitable replacement that will hopefully give good performance and a smooth and consistent idle.

Thanks

Jim

I'm not familiar with how dyno tuning would be done on a twin,,, you didn't mention carb balancing being part of the process,,, I know with my VHB30's on my CX, what I thought were carb problems,, turned out to have been weak electrical signals & coils, solved by Bosch Big Blue coils(tough to fit),,, my final carb tune up/balance using a home made vacumn gauge worked perfectly,,, until I took my first hard turn,,, then I had the same problem you're having,,, idle hanging up etc,,, traced it to poor throttle cable routing (for my bike),,, when I did the rebuild,, I had read of all the recommended throttle cable routes,, and had laid them out on opposite sides of the frame backbone, crossing over under the tank,,, it was pinching some how and hanging up,,, I spoke to Curtis Harper about it,,, and he recommended running the throttle cables straight back along the right side under the tank,,, they are nice and loose now,, not as neat a looking job,,, but no idle hang ups anymore,,, had to rebalance again after that,,, I find the fine balancing and fine air mixture screw adjustment to be the final pieces of the "good running" puzzle, fwiw ymmv

Kelly
2008 California Vintage
2003 V11 Lemans
2007 Griso 1100
1979 G5 & 1980 Lemans CX100
2010 Suzuki DR650 & 1978 SR500

In a time of universal deceit, telling the truth becomes a revolutionary act. George Orwell

canuck750

  • Guest
Re: Carburation improvements for an Eldorado 850
« Reply #21 on: November 02, 2015, 05:27:08 PM »
I certainly hope you put the 'right' ones back in?

I received a pm from a very reputable contributor who asks to remain anonymous and who described what sounds like an air leak through the carb top cover paper gasket or perhaps the head gasket as result of all the fiddling the boys with the dyno carried out. On the weekend I will examine the carb top covers and gaskets, re-torque the heads and check the original jets specs to what has been swapped instead. After providing me with a detailed explanation of how the idle rises and the likelihood of an air leak, it is the cheapest and best place to start!

I will not be so easily tempted to cross pollinate Asian parts into the Italian architecture, (it may work with food, didn't Marco Polo bring back noodles from China and create a sensation in the old country?, but probably not as well with mechanical bits) at least until I thoroughly exhaust all reasonable attempts to make the Dellorto's function as God and Guzzi intended.

Offline 80CX100

  • Gaggle Hero
  • *****
  • *
  • *
  • *
  • *
  • *
  • Posts: 1421
  • Location: Ontario, Canada
Re: Carburation improvements for an Eldorado 850
« Reply #22 on: November 02, 2015, 06:24:19 PM »
I was thinking about my previous response,,, I had a nagging feeling, I had forgotten a part of the solution, that had solved my sticking, erratic high idle,,,

Upon reflection, I recall that the throttle cables themselves had stretched and were a little long for the cable sheathing,,, as a result, after a hard turn, the fitting on the end of the casing, would get hung up inside the ferrule on top of the carb,,, I made a little shim out of a piece of zip tie,, and fit it inside the ferrule, tightening the whole works,,, solved my high erratic idle,,  your solution  might be as simple as that,,,,

 (ps, I read your post re the leaky paper gasket on top of the carb,,, could be,, I had heard this was a problem,, so I replaced it when I rebuilt the carbs)

Kelly
« Last Edit: November 02, 2015, 06:29:49 PM by 80CX100 »
2008 California Vintage
2003 V11 Lemans
2007 Griso 1100
1979 G5 & 1980 Lemans CX100
2010 Suzuki DR650 & 1978 SR500

In a time of universal deceit, telling the truth becomes a revolutionary act. George Orwell

 


Harper's Moto Guzzi : Go Ride, Break Parts, Call me!
Harper's Moto Guzzi. Where we still answer the phone, use the highest quality parts, and also do Transmission, rear drive, and carb rebuilds fast. Call us at 816.697.3411 and get your problems resolved.
http://www.harpermoto.com
Advertise Here