Engine "stumbling" at constant speeds


Information and questions on GL1100 Goldwings (1980-1983)
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forddieselfan2
Posts: 3
Joined: Sun Jun 26, 2016 7:47 pm
Location: Little Falls, Mn
Motorcycle: 1982 GL1100 Naked

Engine "stumbling" at constant speeds

Postby forddieselfan2 » Sun Jun 26, 2016 8:28 pm



Hello everyone! After searching for months, I just picked up an 82 naked Goldwing. The bike runs out great till you reach a speed and try to hold it there. the engine goes from smooth while accelerating than stumbles while holding a constant speed. than when I let off or accelerate again it smooths back out. Also it is getting under 30 mpg. I'm stumped as I haven't been able to find a local mechanic to work on this now that I bought it.
Some history on the bike. 96k miles 8000 miles on belts, rings, head gaskets and carb rebuilds receipts for proof.



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virgilmobile
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Re: Engine "stumbling" at constant speeds

Postby virgilmobile » Mon Jun 27, 2016 7:00 am

Pull all 4 spark plugs and inspect.There condition tells much about how the engine is running.
When its running poorly..add a bit of "choke" to see if it clears up..a lean condition.
If it gets worse,maintain the poor running condition and turn off the fuel to see if if smooths out..A rich condition.This can take several seconds to burn the fuel.
Just a few mm. off on the float setting will change the fuel mixture.

f1xrupr
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Re: Engine "stumbling" at constant speeds

Postby f1xrupr » Mon Jun 27, 2016 12:03 pm

Question-does it idle smooth? If it idles smooth, my guess would be carb slides sticking, and poor fuel mileage do to you tinkering with the throttle at speed. If it idles rough, smokes black, and or, has eye burning exhaust fumes, then you may have a Carb flooding. Caution-if you have a carb flooding, it is critical that you turn fuel off while not running. Fuel that has collected in cylinder can bend or brake a conecting rod while trying to start engine. A flooding carb can also be diagnosed by pulling spark plugs as mention. A black soot on spark plug indicates a rich condition...
My exercise bike is a goldwing.

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mytown
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Motorcycle: 1982 Goldwing Interstate

Re: Engine "stumbling" at constant speeds

Postby mytown » Mon Jun 27, 2016 6:04 pm

Allow yourself room for doubt even though you were presented with PO receipts. At the time of purchase, I twice received $400 dollar receipts for recent carb rebuilds. One for an '81 Silverwing, one for my Goldwing. Very similar carbs. Neither set was rebuilt correctly. Both bikes got down the road but ran poorly in one manner or another. In one instance jets were reversed. Here's one shop's solution to a cracked overflow tube:

I found rebuild how-tos specific to the carbs and did the job correctly, spending little if anything since the parts were new. Like I said, just don't rely on the receipts as proof that the work was done correctly. Heck, in my case the pros made things worse.

f1xrupr
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Re: Engine "stumbling" at constant speeds

Postby f1xrupr » Mon Jun 27, 2016 6:14 pm

mytown wrote:Allow yourself room for doubt even though you were presented with PO receipts. At the time of purchase, I twice received $400 dollar receipts for recent carb rebuilds. One for an '81 Silverwing, one for my Goldwing. Very similar carbs. Neither set was rebuilt correctly. Both bikes got down the road but ran poorly in one manner or another. In one instance jets were reversed. Here's one shop's solution to a cracked overflow tube:
OverflowPlug.jpg

I found rebuild how-tos specific to the carbs and did the job correctly, spending little if anything since the parts were new. Like I said, just don't rely on the receipts as proof that the work was done correctly. Heck, in my case the pros made things worse.

Well...since you broke the ice, I was wondering who could afford to pay a bike shop to re-ring a wing...
My exercise bike is a goldwing.

forddieselfan2
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Re: Engine "stumbling" at constant speeds

Postby forddieselfan2 » Mon Jun 27, 2016 9:25 pm

Thanks for the tips on using the choke and fuel shutoff to help diagnose. I'll try it tomorrow. As for the receipts, I was thinking the same thing.
It looks like I will need to look into whats going on with the carbs anyway, reason being whenever I take off from a stop I have to throttle up above 1500rpm while releasing clutch, otherwise it lugs bad "clunking noise". All three of this generation goldwing that I test rode did this, so perhaps its just the way these are? After some research I've read it may be the carbs are out of sync or something called an air cutoff valve is failing.
BTW it does idle fine.
what has me questioning the receipts. Ive put on about 200 miles so far but today was the first time Ive really got on it. Say 80-85 mph for 20 minutes straight, temp never went above 1/3rd of temp gauge. I get off the freeway and there is drips of coolant on right side of engine coming from under the fake tank I pulled the "tank" and the coolant seems to be coming from near the radiator cap. I really hope its not a sign of impending headgasket issues. I Idled it for 45 minutes with a fan blowing on the radiator and it never got hot or dripped a drop WTF lol. It's looking like I bought a basket case

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mytown
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Re: Engine "stumbling" at constant speeds

Postby mytown » Mon Jun 27, 2016 11:02 pm

When I bought mine I rode it home at 60-75 mph on three cylinders. Check around your coolant return reservoir for the leak. Check the radiator cap, hoses, etc. too. I don't see a basket case at all, not yet, and nothing says head gasket issues to me, but the carbs need to be gotten right. I'd say that these bikes are prone to lugging from a dead stop if just a little out of sync, need cleaning, etc. Others probably know better than I. Make sure you have four cylinders firing, should get a drop in idle as you pull a plug wire, or you can touch the headers to see if they're getting hot. I'd get the coolant leak figured out then move on to the carbs so I wouldn't have worry about coolant/overheating while figuring out the carbs.

forddieselfan2
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Re: Engine "stumbling" at constant speeds

Postby forddieselfan2 » Sun Jul 03, 2016 11:33 am

here is the update on the test you suggested. while riding at a constant speed if I shut off fuel petcock it continues to stumble till it starves for fuel and dies. I tried the choke test next. while riding and holding a constant speed I pull the choke slowly and boom the stumble totally goes away. the only problem is that if I try to accelerate it starts to miss bad and lose power unless I accelerate slowly. any tips as to wich part of the carbs I should start with. as for the coolant leak I rode for 70 miles at 60 with no issues. came home parked it overnight, the next morning took it for an easy 20 minute ride pulled over and checked "no leak" so I took it for a 10 minute cruise at closer to 90 and pulled over and I had coolant drops all over the right side of the motor from the radiator cap again

robertdawber
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Re: Engine "stumbling" at constant speeds

Postby robertdawber » Mon Jul 04, 2016 8:06 am

forddieselfan2 wrote:here is the update on the test you suggested. while riding at a constant speed if I shut off fuel petcock it continues to stumble till it starves for fuel and dies. I tried the choke test next. while riding and holding a constant speed I pull the choke slowly and boom the stumble totally goes away. the only problem is that if I try to accelerate it starts to miss bad and lose power unless I accelerate slowly. any tips as to wich part of the carbs I should start with. as for the coolant leak I rode for 70 miles at 60 with no issues. came home parked it overnight, the next morning took it for an easy 20 minute ride pulled over and checked "no leak" so I took it for a 10 minute cruise at closer to 90 and pulled over and I had coolant drops all over the right side of the motor from the radiator cap again

The coolant could be a number of things. The hose to the reservoir could be loose or even off. Those leaks are a pain to find.
I will be curious to hear what others say about what to do now that your issue with the stumbling left with the choke out.

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virgilmobile
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83 GL1100 standard
84 GL 1200 I

Re: Engine "stumbling" at constant speeds

Postby virgilmobile » Mon Jul 04, 2016 10:39 am

Now that you determined that it's a bit lean,narrow this down a bit.Is it lean at any rpm above 1500?
My 1200 stumbled between 1500-2500 rpm .
Above and below it was smooth.
Mine was a mid range stumble only.
If yours stumbles anywhere but a idle,look at 2 things.First verify the slides do move up and down as you rev the engine.Use a mirror in the plenum box. The next Likely problem is low fuel level.Raise it 2mm.
If it's only in the mid range and the slides do work,concider raising the slide needles to enriched the fuel.I did mine with a couple of small washers.

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virgilmobile
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Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
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Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: Engine "stumbling" at constant speeds

Postby virgilmobile » Mon Jul 04, 2016 11:38 am

The float level "2mm" part.i read that they've been rebuilt.Float settings are critical.Being off just 2 mm will cause problems.They must be set accurate and dead level just resting in the spring loaded needles.Sorry bout the lack of info.
Also be sure the carb mounting "O"rings are in good shape and the carb clamps are secured.Dont want any unauthorized air getting in.

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mytown
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Re: Engine "stumbling" at constant speeds

Postby mytown » Mon Jul 04, 2016 3:34 pm

Something that suggests to me low fuel in the bowls is that it straightens out upon acceleration. Maybe it straightens out when you accelerate because the accelerator pump is compensating for low fuel in the bowls :?: :shock: :?:

Check everything you can check without removing the carbs. Clamps and intake o-rings are a great start. I'd replace the fuel filter and air filter. I've never checked the slides with a mirror but sounds like a relatively simple and effective diagnostic tool. Fuel starvation can result form a dirty gas cap as there is a vent hole that can get plugged. Make sure there are no crimps in any part of the fuel lines.

Once you've done all the non-invasive things, It will be time to pull the carbs, paying particular attention to the fuel level in the float bowls. There's lots of good tutorials on doing this and on cleaning/rebuilding the carbs. You can also send them out to be done by re-builders who know what they are doing.

Regarding float levels, I recently read of aftermarket float needles being a hair too long and thereby lowering the fuel level in the bowls and resulting in fuel starvation at higher rpms. Go Honda with these if you can.

Your bike sounds like it has promise. Looks like you have good spark and no overheating. I'd do a compression test at this point just to verify that I have a decent engine.

Don't be dismayed. Having to get the carbs right after purchase seems to happen quite often. I'm three for my last three. :shock:




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