GL1000 Popping back through #2 Carburetor.


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GL1000 Popping back through #2 Carburetor.

Postby burdger » Wed Sep 26, 2012 7:45 am



1976 Honda Goldwing. Makes popping sound through the # 2 carburetor. I can feel the pressure with my hand as it is in the plenum. Definitely comming from # 2 cylinder. I also hear a tweeting noise around the left side of the muffler. I removed the exhaust system and checkled for any restriction. Found none. I have run the engine without the muffler installed and still had the popping noise. Reinstalled the muffler with new gaskets. Carbs were rebuilt by Pistol Pete. New timing belts installed. Ignition and cam timing is spot on. Valves adjusted to .004". Compression on all cylinders 165-170. Changed ignition system over to electronic (Dynatek) coils, wires, plug caps, plugs. Have rotated plugs. Plug reading, # 2 plug always is darker. It popped back through with the points system, too. Tried a different set of cleaned and rebuilt carburetors. Same results. Checked crankshaft markings and verified that TDC marks were actually TDC at the piston. Removed both cylinder heads and had valve job done on both. New valve seals, head gaskets, o-rings (all genuine Honda parts). No change. Found another left cylinder head complete with camshaft. Did valve job on it and installed. Same results, still pops back through the # 2 carburetor. What else can it be? I'm out of ideas. Help.


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Re: GL1000 Popping back through #2 Carburetor.

Postby scotterichmond » Wed Sep 26, 2012 9:36 am

wow! I would think you have been as thorough as possible. my first thought after seeong all that has been done, was a flat cam. But ublees both cams are the same , you can rule that out.
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Re: GL1000 Popping back through #2 Carburetor.

Postby virgilmobile » Wed Sep 26, 2012 11:32 am

This is kinda off the wall but here goes.
There exists what is called a scavenge cycle.A point where the valve opening overlaps.
Obviously if the cam is off by a tooth,it will change this.
Now all that's been checked many times ...you have eliminated all possibilities.....except one.
The exhaust header.
On the gl1000..the exhaust header pipes have a inner thermal liner.It extended from the mounting flange down into the pipe several inches.
I did have one gl1000 that had a swollen liner 4" into the pipe and was creating back pressure on one cylinder.
****I didn't notice it till I reversed the headers from left to right sides,hung the exhaust off them and my problem followed the header.****
A $20 header fixed that one.
With a flashlight I saw the bulge in the liner.It was not apparent from the outside.
The engine needs to 'breathe' properly and any restriction will screw up the scavenge cycle.
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Re: GL1000 Popping back through #2 Carburetor.

Postby scotterichmond » Wed Sep 26, 2012 11:37 am

you said you ran it without headers , right?
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Re: GL1000 Popping back through #2 Carburetor.

Postby virgilmobile » Wed Sep 26, 2012 11:52 am

He ran it without exhaust pipes.Headers in place.The only part not changed.
I reversed my headers left to right.The exhaust sticking out the front of the bike.
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Re: GL1000 Popping back through #2 Carburetor.

Postby scotterichmond » Wed Sep 26, 2012 12:08 pm

got it. I should read closer and not just scan, huh?
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Re: GL1000 Popping back through #2 Carburetor.

Postby virgilmobile » Wed Sep 26, 2012 12:23 pm

Well....in a word....details my boy..details :D
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Re: GL1000 Popping back through #2 Carburetor.

Postby portugeezer » Wed Sep 26, 2012 10:27 pm

Take the intake manifold off and check the rubber O ring. If it's cracked you're sucking air and there is your pop!
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Re: GL1000 Popping back through #2 Carburetor.

Postby scotterichmond » Thu Sep 27, 2012 9:09 am

portugeezer wrote:Take the intake manifold off and check the rubber O ring. If it's cracked you're sucking air and there is your pop!

that could be ! too !
I just had that on a friends bike.
you obviouslly had the carbs off ( pistol pete's rebuild) but it is very easy for the orings to slip out of place. and I assume you used new orings ..... right?
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Re: GL1000 Popping back through #2 Carburetor.

Postby scotterichmond » Thu Sep 27, 2012 9:10 am

another thought............. could be a vaccum leak in the rubber intake connection too.
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Re: GL1000 Popping back through #2 Carburetor.

Postby portugeezer » Thu Sep 27, 2012 2:56 pm

When I got my 1100 it was popping and the right side pipe was as blue as can get. I had only two of 4 O ring gaskets in there! I had the carbs out twice before I got that all resolved! I also should add that I used a cheap homemade manometer to sync my carbs and it worked better than the nice mercury one I got to use on my GL1000 so well in fact that I'm going to sync the carbs on my GL1000 with it! My point is once you get that pop squared away don't be afraid to sync with a $10 manometer!
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Re: GL1000 Popping back through #2 Carburetor.

Postby virgilmobile » Thu Sep 27, 2012 4:10 pm

[quote="portugeezer"] I also should add that I used a cheap homemade manometer to sync my carbs

OK ....show us the money...uh.... pictures...Don't tease us with the "homemade" part.I wanna see it. :D

Do tell all and even a video would be nice to watch.
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Re: GL1000 Popping back through #2 Carburetor.

Postby portugeezer » Thu Sep 27, 2012 8:03 pm

Ok, Pics of the manometer are easy! I made it with aquarium tubing mounted to a 1X4 I put a garage door hinge on a second piece of 1X4 so it folds on its own stand I filled it by sucking in some 2 cycle oil because its blue! I used garage door opener staples on the tubing I will post pics my next slow day. I could post pics of the sync on the GL1000 step by step if you'd like.
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Re: GL1000 Popping back through #2 Carburetor.

Postby dingdong » Fri Sep 28, 2012 7:53 am

If your #2 plug is burning darker that the rest it most likely isn't a vacuum leak. A vacuum leak causes a lean condition.
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Re: GL1000 Popping back through #2 Carburetor.

Postby burdger » Fri Sep 28, 2012 2:33 pm

Virgilmobile was right. The inner liner had almost completely closed off the exhaust. It was about three inches below the exhaust port. I couldn't believe how smooth the liner had sagged down and closed off the I.D. by approximately 90%. Thanks for everyone helping.
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Re: GL1000 Popping back through #2 Carburetor.

Postby scotterichmond » Fri Sep 28, 2012 2:38 pm

Glad you found the issuse.
Virgil, good job, it can be hard to diagnios by words alone. you expetise is highly valued.
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Re: GL1000 Popping back through #2 Carburetor.

Postby virgilmobile » Fri Sep 28, 2012 6:42 pm

When I read that the problem persisted after doing two of everything, it was a process of elimination.the header was all that was left.
It's odd too.I've only seen this once before back some 15 years ago and no one had ever had that problem before.The thermal liners just don't do that...well so says mother Honda.


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