full throttle stumble


Information and questions on GL1100 Goldwings (1980-1983)
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eklimek
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full throttle stumble

Postby eklimek » Mon Jun 06, 2011 4:31 pm



81 new - to -me 39,000 km (Canada).

Idles, starts, runs no smoke, but ..... left bank "pop" exhaust with deceleration. No backfire into carbs. Have not compression tested but finger pressure in all four holes.

No intake vacuum leaks found with acetylene. Cyl #3 and #4 plugs are white. #1 and #2 are black. Has stumble at speed acceleration at 75 mph full throttle falls flat.

Filter changed and good gravity flow from tank. Filler cap loosened. Have tried fuel injector cleaner and drained fuel bowel #4 no difference. Fuel pump noted pulsatile flow.

So, ... is this carb rebuild time? If so, I have donor 81 assembly. But do not relish thought of doing this. Recommendations? - synchronize first? send the assembly away to be rebuilt?



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virgilmobile
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Re: full throttle stumble

Postby virgilmobile » Mon Jun 06, 2011 7:34 pm

The quickest and usually most effective improvement is a very good sync job.The closer the better.

macka
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Re: full throttle stumble

Postby macka » Thu Jun 09, 2011 6:17 am

synchronise first, and also sea foam (usually found at NAPA up here) in the gas may help degunk the carbs. If you have the spare set, you might as well rebuild them, and swap them out over the winter if the simple fixes work. If not they can be swapped out as soon as they are ready.

DragonRider
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Re: full throttle stumble

Postby DragonRider » Thu Jun 09, 2011 11:14 am

Ok, try this.. Yes sync the carbs but first drain all four bowls and all four plugs.
I would use a can of seafoam in the oil run it for 30 to 50 miles and drain it changing oil and filter (this will get about 90% of the gunk out of the enging and allow all the parts inside to move freely). Add capful or two of seafoam to your gas as this will help clean your fuel system.
Check your spark, it is possible you are having a spark problem. Look at you fuel lines are any being crimped? when you accelerate the throttle linkages move and I have had a fuel line get pinched causing my engine to stumble (took me two weeks to find that simple problem).

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eklimek
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Re: full throttle stumble

Postby eklimek » Thu Jun 09, 2011 11:53 am

Thanks for advice. I will test compression and sync all carbs this weekend.

I have already degunked the oil. I will not drop the carb float bowls wiith full removal. My experience with destruction of #4 float bowel drain plug will also temper my enthusiasm for examining 1 - 3 . Any advice on loosening these plugs?

macka
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Re: full throttle stumble

Postby macka » Thu Jun 09, 2011 12:52 pm

take the float bowl right off and soak it in atf.

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eklimek
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Re: full throttle stumble

Postby eklimek » Thu Jun 09, 2011 1:28 pm

To estimate the complexity I took the spare 81 carburetor entire assembly out. First time, about one hour shop time ... to remove.

Adding rebuild and replace time to the bottom line, I would rather send the entire spare assembly out to be rebuilt rather than take the functioning one out of service for the entire day just for this. That way I can be reasonably sure it is done .... once ... correctly.

More after the weekend.

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eklimek
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Re: full throttle stumble

Postby eklimek » Sat Jun 11, 2011 2:33 pm

update - compression test with 30 wt oil in chamber 100 -125 #2 and #4 being lowest.
fully synchronized carbs and new air filter - no change.

Still falls off at 4500 rpm with full throttle. seems to die until off throttle.
reaches 75+ mph if one builds up to it with submaximal throttle.

Maybe its ring time? Or the change to dual Harley Davidson mufflers has made the difference? Or should I be chasing ignition?.

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virgilmobile
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Re: full throttle stumble

Postby virgilmobile » Thu Jun 16, 2011 4:19 pm

When you did the compression test,was the throttle wide open?please say no,i forgot and that's what gave me the low uneven readings.
My 83 gl1100..dry cylinders,wide open throttle,compression tested 95,135,100,85.A very poor reading.
wet test,2 tps oil in each cylinder improved compression 20%.I'm looking for even(within 5psi)compression.
It would "run",badly,sooted 2 plugs,lacking power,off idle rattle,etc.
I re-ringed it..now 160 psi dry on each cylinder,smooth as silk and a steady grin from 0-80mph.Then I shifted into 4th gear.
lastly,factory limit compression is 145 psi with a 4 psi difference.130 would still be just OK.150 is pretty good and 165 will pull great.
Did you adjust the valves?

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eklimek
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Re: full throttle stumble

Postby eklimek » Thu Jun 16, 2011 6:18 pm

No. Never thought to open the throttle. Just turned over wet. Curious how that would make difference at crank over speed (all plugs removed). If so, would also be different running on 3 cylinders measuring 4th? Will add to "to do again" list.

Thought to remove all mufflers and see if top end still falls off - testing back pressure theory. Seems to run well on 2/3 throttle on decline at any illegal speed I care to drive.

Was then going to focus on ignition. Seems failing coils tend to show up under such duress, according to mechanic friend. Could vacuum advance be related to this?

I had deferred replacing belts and doing tappets because of carburetor problem previously alluded to.

Note now also intermittent failure of fuel and temp gauges suggesting imminent order of new 7V regulator.

Consoling self that this is fun. I could really buy a Kawasaki ZR14 donor bike, but surviving riders are half my age. Harley loud and besides, leather tank tops, tramp stamps and thong accessory hard to come by for similar reason. Nah, would never join a club that would have me. Bedsides you're all so kind to put up with my rambling.

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WingAdmin
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Re: full throttle stumble

Postby WingAdmin » Thu Jun 16, 2011 8:35 pm

No consoling required - this IS fun! :) The 1100 is a gem to work on, not hard to get to stuff, once you've figured out how things come apart and go together, for the most part it's easy.

RexAubrey
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Re: full throttle stumble

Postby RexAubrey » Fri Jun 17, 2011 12:03 am

I have to agree with WingAdmin, In the last month i have learned more about the 1100 than I have ever learned about my previous bikes. and i still have to take the 1100 out for the first ride...lol

Rex
Rex
1983 GoldWing Interstate, 1982 GoldWing Aspencade, 1981 Yamaha 550 Maxim, 1979 Yamaha 650 Special

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virgilmobile
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84 GL 1200 I

Re: full throttle stumble

Postby virgilmobile » Fri Jun 17, 2011 7:45 am

Opening the throttle allows clear air flow into the testing cylinders,closed throttle restricts air flow(vacuum)and will not allow the cylinder to gulp as much air as it needs to compress.A balance of compression readings is more important than how much,eg:100,80,145,130 will result in a poor idle and acceleration rattle.110,112,108,115 even being low,will be a smoother runner.

Wide changes (110 then 150) between dry and wet indicates a poor ring seal,a good indication of a needed ring job.Although,I've run bikes at that compression,they don't preform very well.

Vacuum advance is important in getting the desired power curve and should be tested.The vacuum ports in the carb body can get plugged and the advance mechanism itself can stop moving.

Theoretically speaking,changing the exhaust system can alter the "back pressure".Each engine is engineered with a precise control of exhaust flow.Altering it 'can' change the scavenge cycle to that cylinder.Too much restriction in the exhaust and the cylinder can't get rid of the spent fuel and clear the chamber for the next load.To little back pressure and the cylinder floods with too much fuel and some passes into the exhaust system(popping in the exhaust).

I have used Harley pipes on a gl1000.The math says that a single Harley exhaust is designed to run with a cylinder about the same CC displacement.

Yes coils can fail under strain,and the ignition module and pickup coils too.They can be tested by a mechanic with the proper equipment.Remember,there are 2 of everything and each one is tested separately.

At least adjust the valves before you go all out on the rest of this stuff,It is important and free and takes about an hour.

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eklimek
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Re: full throttle stumble

Postby eklimek » Fri Jun 17, 2011 2:54 pm

Thanks virgilmobile

update -

Compression with wide open throttle all plugs removed is 150-160 across the board. Big difference WOT. 20w-50 oil nice day engine warm.

Plugs gapped. Removed exhaust, ran without, no difference.

Out of curiosity clamped off vacuum advance line, no difference.

Swapped out entire coil assembly from donor bike, no difference. Was going to swap coils front vs rear individually separately but this was easier.

Previously have changed fuel/air filter and degunked engine oil x2 and run tank dry with injector cleaner and gumout

Have not yet : changed timing belts, adjusted tappets,confirmed ignition timing is correct, measured fuel pressure or volumes, rebuilt carbs, confirmed low or high voltage circuit at 5,000 rpm.

comments welcome

macka
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Re: full throttle stumble

Postby macka » Fri Jun 17, 2011 8:33 pm

check your timing and tappets first. From experience, I find running seafoam 1/2 cup to a tank makes more of a difference then a cap full. I also find rebuilding the carbs the best if you are having fuelling issues. Most of the degunker stuff doesn't hold a candle to a proper clean out if they sat for more then 6 months with stale gas.

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eklimek
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Re: full throttle stumble

Postby eklimek » Mon Aug 29, 2011 8:43 am

Problem appears to have been carburation. After trying Seafoam in tank a few times I wondered if there was any way to avoid rebuilding the carb. For what it's worth, this is what I did.

Fuel injector cleaner was fed via the fuel pump "neat" (100%, 200 proof). The cleaner will stall the engine. However from my diesel days I recalled ether spray. The motor can be kept running on ether sprayed in the intake. This will fill the bowels and smoke up the exhaust as the injector cleaner passes into the combustion chambers.

Reconnect the gas tank and flush the injector cleaner, again running the engine on ether.

When the engine finally runs on gas this won't take long since if fast idle at 3,000 rpm. She will smoke until all injector cleaner is flushed. I then changed the oil.

For what it's worth.

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eklimek
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Joined: Tue Feb 15, 2011 1:55 pm
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Motorcycle: 81 GL1100 (Widowmaker not in service), 83GL1100, CB350f x 6, CB400f x2, CB550f sold, CL350 (seized engine), plus enough donors to take me through retirement.

Re: full throttle stumble

Postby eklimek » Mon Aug 29, 2011 4:16 pm

fuel injector cleaners - ingredients from this web site
http://www.bobistheoilguy.com/forums/ub ... er=1187818

MSDS data:
-------------------------------------------------------------------------------------------------
Techron Concentrate
Distillates, hydrotreated light < 50 %weight Aka: Paint thinner(oil based)
Stoddard solvent < 35 %weight Aka: dry clean solvent, white solvent
Solvent naphtha, light aromatic 5 - 10 %weight : zippo lighter fluid
Benzene, 1,2,4-trimethyl- 95-63-6 1 - 5 %weight : powerful toxic solvent
Xylene , powerful solvent

Techron is naptha and 3 kinds of benenze.
-------------------------------------------------------------------------------------------------------
GUM OUT INJECTOR CLEANER (WINTER GRADE)

Chemical Percent
Trade secret or proprietary formula < 1 ( secret #1)
Petroleum distillate(s) (unspecified) 40-70 ( most likely paint thinner)
Detergent/Inhibitor mixture 1-10 ( secret #2 )
Isopropanol 30-50 (rubbing alcohol, GAS DRYER "CH3CHOHCH3")
-------------------------------------------------------------------------------------------------------
Seafoam ingredients:
1 PALE OIL 4229 40-60% = A base or process oil refined until its color = yellow.
2 NAPHTHA 20 25-35% solvent powerful , common in all good injector cleaners. Zippo juice !
3 IPA 125 10-20% = Isopropyl Alcohol (rubbing alcohol),
---------------------------------------------------------------------------------------------------------

"GM TEC" ingredients:

2-BUTOXYETHANOL, a paint and ink solvent , used even in Clorox cleaner 409
Naptha, , raises octane rating of gas, , simular to Zippo ligher fluid. Coleman camp fuel.
4-METHYL-2-PENTANOL, (aka:Methyl isobutyl carbinol) used as a lacquer paint tinner
9-OCTADECENDIC ACID.(aka:Oleic acid, found in Olive oil)

--------------------------------------------------------------------------------------------------------------
BG-44k:

Light Aromatic Solvent Naphtha , ( Zippo lighter fluid)
1, 2, 4-Trimethylbenzene , commonly found in up to 7% by volume already in Gasoline.
Xylene ,(1,2-dimethylbenzene & 1,3-dimethylbenzene & 1,4-dimethylbenzene), xylol , powerful solvent
Cumene ,(isopropylbenzene, ) powerful solvent,raises octane of gasoline.
-----------------------------------------------------------------------------------------------------------
GUNK , RADIATOR SPECIALTY COMPANY, FUEL INJECTION AIR INTAKE CLEANER

2-Propanone 30-60 % aka: Acetone
Ethylbenzene >10 % a powerful solvent
Hydrotreated Heavy Paraffinic Distillate 1-10 % weak solvent
Methanol 1-4% , solvent.
Propane 10-30% , gas
Toluene 15-45% ,powerful solvent
Xylene (mixed isomers) 5-20%
--------------------------------------------------------------------------------------------------------
Red Line SI-1
1-5% Alkenylamine - (a detergent ,even used sometimes,in baby shampoo)
1-10% Isoctanol - ( C8H18O , aka, 2-ethylhexan-1-ol, or Octyl alcohol)
1-10% 1,2,4 Trimethylbenzene , (C9H12 )
5-20% Aliphactic Napthta , zippo lighter fluid. , aka: white gas, low octane)
--------------------------------

Valvoline Complete Fuel System Cleaner
52 - 62% Kersosene
28-38% Light hydrotreated petroleum distillate
6-16% Stoddard Solvent ( stoddard is the name of the man who invented dry cleaning)

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eklimek
Posts: 307
Joined: Tue Feb 15, 2011 1:55 pm
Location: St Catharines Ontario Canada
Motorcycle: 81 GL1100 (Widowmaker not in service), 83GL1100, CB350f x 6, CB400f x2, CB550f sold, CL350 (seized engine), plus enough donors to take me through retirement.

Re: full throttle stumble

Postby eklimek » Mon May 14, 2012 10:56 am

The full throttle stumble was resolved with rebuild of carbs. Sent them to Pistol Petes in Tennessee over the winter. No chain rattle, terrifying acceleration and more top end than I will ever need.

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SteveB123
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Re: full throttle stumble

Postby SteveB123 » Mon May 14, 2012 3:09 pm

What did that run you $, from Canada, if you don't mind?
Current:82 GL1100 Interstate, 60 Amp Poorboy, MSD coil
Previous: 93 GSX1100F Katana
82 GL500 Silverwing

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eklimek
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Motorcycle: 81 GL1100 (Widowmaker not in service), 83GL1100, CB350f x 6, CB400f x2, CB550f sold, CL350 (seized engine), plus enough donors to take me through retirement.

Re: full throttle stumble

Postby eklimek » Mon May 14, 2012 3:55 pm

Cost of shipping down was more than US Postal return. Think it was about $40 plus Pstol's cost. ask them.

I was unprepared to do all 4 then reassemble only to have messed one up. R & R was about 3 hour. Tight squeeze very carefully engineered to "just fit". Congrats Mr Honda.

Actually sent Pistol the set from my donor bike to refurbish over winter. They weren't pretty and they came back just fine.

Anyone with tips on easy R & R for vacuum advance would be appreciated. little beaver?




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