78 GL1000 Timing Question


Information and questions on GL1000 Goldwings (1975-1979)
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mikeikedc
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Motorcycle: 1978 GL1000

78 GL1000 Timing Question

Postby mikeikedc » Fri Jul 17, 2015 8:13 am



I am resurrecting a 78 and have been able to find answers so far just by searching the archives but now I am stumped. It runs rough, backfires when I let off the throttle, cuts off, etc. I replaced the timing belts. I checked valve clearance and replaced just points (set gap) but did not check timing before I synchronized the carbs. My gauges showed low vacuum (possible timing off) so I went back to check the timing. In using the manual method (with test light) the light shines on both sets of points at F2 and neither of them at F1???? I went through many full rotations just to be sure. What am I missing here?



SnoBrdr
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Motorcycle: 1978 GL 1000

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Re: 78 GL1000 Timing Question

Postby SnoBrdr » Fri Jul 17, 2015 9:52 am

mikeikedc wrote:I am resurrecting a 78 and have been able to find answers so far just by searching the archives but now I am stumped. It runs rough, backfires when I let off the throttle, cuts off, etc. I replaced the timing belts. I checked valve clearance and replaced just points (set gap) but did not check timing before I synchronized the carbs. My gauges showed low vacuum (possible timing off) so I went back to check the timing. In using the manual method (with test light) the light shines on both sets of points at F2 and neither of them at F1???? I went through many full rotations just to be sure. What am I missing here?


How long has it sat?

If it has sat for any period of time, you NEED to totally rebuild the carbs.

Running rough, backfiring and cutting out are all signs of carb issues.

If you still think it's the timing, check this: http://ngwclub.com/forum/viewtopic.php?t=10527

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WingAdmin
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Re: 78 GL1000 Timing Question

Postby WingAdmin » Fri Jul 17, 2015 10:34 am

You might have a vacuum leak after the carbs. When you let off the throttle, vacuum increases. If you've got a vacuum leak, you're going to be sucking in air, which will make the mixture lean. A lean mixture can cause backfiring like you describe.

Take an (unlit!!) propane torch, and with propane coming out gently, move it around the intake runners and near the bottom of the carbs while the engine idles. If the engine speeds up when you get the propane near a certain spot, it could indicate the location of a vacuum leak.

mikeikedc
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Re: 78 GL1000 Timing Question

Postby mikeikedc » Fri Jul 17, 2015 10:57 am

Tried the WD40 trick looking for vacuum leak and did not see any change in idle. I like the propane idea better. I will get to the carbs eventually because I do not know how much it ran in the 7 years the previous owner had it. It would start and run like it does now when I bought it. Want to solve this timing thing first. I was hoping someone had seen this before. I will check it again following the ngw post and see if it was user error.

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Ncscooter
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Re: 78 GL1000 Timing Question

Postby Ncscooter » Fri Jul 17, 2015 2:44 pm

Make sure there's no short where the wires come under the points cover. Changing gap changes timing and so forth. Mine did this, I think I had an alligator clip that was grounding something by accident. Light stays on for a good bit of the rotation. Here's a nice discusion of points on the GL1000 >> http://www.randakksblog.com/secret-igni ... #more-1440 << After you get the ignition nailed down, move on to the carbs. Good advice above. Check for rust in the tank and replace the filter and hoses. The air cut-off on the front top of the carb may be the problem. Idle mix screws would be another popular check point. Intake runner boots should be checked for tightness after the engine is warm. Ethanol will eat the original seals, if you rebuild, I feel Randakk's kit is complete and worth the investment. Good luck! Running well, these bikes are a joy to ride.
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Old Fogey
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Re: 78 GL1000 Timing Question

Postby Old Fogey » Sat Jul 18, 2015 8:16 pm

Randakk's kit is the ONLY one I will use in my customer carb rebuilds. Not cheap I know, but you are only wanting to do these once.
The carbs on these early bikes are their Achilles Heel. The idle circuits clog up easily when left sitting with fuel in them. You will probably need to get them ultrasonically cleaned to get them properly clean.
One tip, tighten the manifold clamps on the rubbers with the engine HOT. You will be surprised how much more you can get on them. That has cured quite a few folks weak running. In fact, I advocate Randakk's manifold clamps as well. They made a difference on my bike.
If you need new fuel hoses (If?? Your old ones are probably the original 40 year old ones, as are your vacuum pipes on the carbs) I can supply you with either or both.
http://www.wingovations.com/braided-fue ... 4579471070
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Fred Camper
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Re: 78 GL1000 Timing Question

Postby Fred Camper » Sun Jul 19, 2015 12:49 pm

Sure seems like the air cut off valve would be a good first look before digging into the carbs. Both Mike Nixon's book and Randaks video are good investments.

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spiralout
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Re: 78 GL1000 Timing Question

Postby spiralout » Sun Jul 19, 2015 1:04 pm

Like Ncscooter said, get your static timing spot on then carbs and/or vac leaks. I use the method where my light comes as soon as the points open. When setting your left side the light should come on at F1 and stay on until after F2 has passed and vice versa for setting the right side. More info here and here

mikeikedc
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Re: 78 GL1000 Timing Question

Postby mikeikedc » Mon Jul 20, 2015 8:45 am

Thanks all. I used the test light in series with the battery and it worked like it should. The previous owner had used a punch in between the points plate and case apparently to try and lock it in place..... Anyway, pried out the plate and replaced and was able to set the timing. Was told about a little trick of leaving one of the base plate screws a little loose. That seemed to work too. Runs pretty well now but still backfires a bit and will cut off when letting off the throttle every once in a while. Will move on to possible vacuum leak and then carbs.

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Fred Camper
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Re: 78 GL1000 Timing Question

Postby Fred Camper » Mon Jul 20, 2015 7:05 pm

After doing my carbs with Randaks video and Nixon 's booklet, I had a sometimes cutoff after dropping the throttle. I increased the idle speed until the cutoff stopped. Then after about 200 miles into a trip, the idle speed jumped up to 3000. Once set back down, no more cutout. So something must have been blocked in those "clean" carbs that did clear out by itself.




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