'79 Throttle response issue


Information and questions on GL1000 Goldwings (1975-1979)
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crobii
Posts: 3
Joined: Mon Apr 30, 2012 9:27 am
Location: Pass Christian, MS
Motorcycle: '79 GL1000, '76 GL1000, '75 GL1000, '97 Valkyrie Tourer

'79 Throttle response issue

Postby crobii » Thu Jun 23, 2016 7:25 pm



Hello Everyone,
I have referenced this board for issues with each of my GL's but have never actually posted. So, here goes...I'm having issues with my '79. The throttle response is bad at 1k-1.2k and then picks up and responds fine above 1.2k. I pulled the carbs and went thru the jets, checked the floats, and checked the slides(carbs rebuilt with a Randakks kit about 3k miles ago). When it continued after re-install, I started some basic troubleshooting and began by pulling spark plug wires, one at a time to see if I was chasing another issue. When I pulled #1, nothing changed...not the idle and not the throttle response....so, I checked the rest and each gave me the result I'd expected (loss of cylinder.) So my problem seemed to be with #1. Checked the valves, right on spec. Checked for spark, looks fine. Swapped plugs, didn't change. Swapped wires, didn't change. Checked timing just to make sure, and it was good. Not seeing any smoke, and at higher idles, it is smooth as silk. One last thing, only running straight gas. I'm running out of options and was hoping to coax some knowledge out of the guru's here. Any help would be appreciated.
Thanks,
Charles



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dingdong
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Re: '79 Throttle response issue

Postby dingdong » Fri Jun 24, 2016 6:41 am

Do you still have points? Have you made sure the mechanical timing advance is moving smoothly? Point adjustment can cause a hesitation and it will feel just like a fuel delivery problem. Point adjustment on these old ladies is critical and the reason many switch to a Dyna E I.
Tom

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crobii
Posts: 3
Joined: Mon Apr 30, 2012 9:27 am
Location: Pass Christian, MS
Motorcycle: '79 GL1000, '76 GL1000, '75 GL1000, '97 Valkyrie Tourer

Re: '79 Throttle response issue

Postby crobii » Fri Jun 24, 2016 7:55 am

Tom,
Thanks for the response, but I have a Dyna S ignition with Dyna coils and wires. That was installed about the same time I rebuilt the carbs. Maybe 3,000 miles ago.

Charles

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virgilmobile
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84 GL 1200 I

Re: '79 Throttle response issue

Postby virgilmobile » Fri Jun 24, 2016 9:07 am

Is the compression within 5psi of the other cylinders and above 120 psi?
Is the dead cylinder plug tan or sooty black?
Did you sync the carbs?
If you pick up the idle to 11500 rpm and pull that plug is it firing that cylinder?
Using a mirror,can you verify the slides move when the engine is revved.?

crobii
Posts: 3
Joined: Mon Apr 30, 2012 9:27 am
Location: Pass Christian, MS
Motorcycle: '79 GL1000, '76 GL1000, '75 GL1000, '97 Valkyrie Tourer

Re: '79 Throttle response issue

Postby crobii » Fri Jun 24, 2016 10:36 am

Is the compression within 5psi of the other cylinders and above 120 psi?
---When I checked last, all were very close. Motor only has 30K on it and has never been abused...

Is the dead cylinder plug tan or sooty black?
---Sooty black

Did you sync the carbs?
---yes, have a DigiSync and can sync carbs relatively quickly now...

If you pick up the idle to 11500 rpm and pull that plug is it firing that cylinder?
---hoping you meant 1500, and if so, yes it does appear to be firing then.

Using a mirror,can you verify the slides move when the engine is revved.?
---I can, but I haven't. I will do that this afternoon. I've always been able to hear the slides on the right side...

Thanks,
Charles

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virgilmobile
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Re: '79 Throttle response issue

Postby virgilmobile » Fri Jun 24, 2016 11:18 am

Thank you for the good information.
Process of elimination.
Spark OK
Compression OK
All that's left is fuel mixture.
Sooty plug is unburnt fuel.
If it were lighter than the rest it would be a lean condition.It must be too rich.
Yes 1500 rpm.sorry.This is when the main jets start to kick in.That carb must be providing enough fuel for that cylinder for that rpm and not tapering down for a idle mixture.
Concentrate on that one carb/cylinder.Something must be different with it compared to the rest.
Its not firing until you get a large air flow to match the fuel being supplied.
Two or 3 things come to mind..
Float level too high.One could run the bike a few minutes and drain that one carb and measure the fuel amount and compare it to another carb.
Stuck open slide allowing excess fuel into one carb through the main jet.
Missing or damaged slow speed jet not metering fuel delivery.
The last possibility may be the throttle plate is not closing the same as the rest.

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virgilmobile
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82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: '79 Throttle response issue

Postby virgilmobile » Fri Jun 24, 2016 11:43 am

Also..Keep in ming that (we) cannot see your bike and this is a analysis for the given information of the most likely things to look at.

I have seen obscure things too.
My personal gl1000 had similar problem...ran poorly on one cylinder...It also had a unusual running noise from one side of the engine..Almost like a low engine knock.More than just a misfire noise.
It was a very rare problem in the exhaust header.
The header has a inner thermal liner.Mine had swolen almost shut about 2" below the mount.
It effectively restricting air flow on one cylinder.

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Re: '79 Throttle response issue

Postby bustedwing » Sat Jun 25, 2016 7:31 am

I know that you have done a lot of work to the carbs, but I would try some fuel additive to clean out any gunk left in the system. I do this every first tank of fuel, even tho I use a stabilizer during storage. The engine is a little stubborn during that first tank, but when I get fresh fuel on board it usually clears right up. I hope this helps. Ride safe.


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