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post #1 of 10 (permalink) Old 08-01-2006, 10:14 AM Thread Starter
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I had recently acquired a 78 GL1000 & was told it needed some tlc to get it to run and it had to be put back together, for Free I could not complain cuz it is a pretty good bike still with 58,000k on it. I had finally got it running last night after spending a week freeing the floats in the carbs and cleaning them, but when it is running at a idol it backfires out the pipe on the one side, that same side also has a hole in the pipe before the muffler, would that have anything to do with it or do I have a diff problem I should be looking for.

Yamaha R1 sportbike rider that has been given
a Goldwing gift and loving it.
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post #2 of 10 (permalink) Old 08-01-2006, 10:22 AM
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The hole in the pipe could very easily cause this, backpressure changes change how the engine runs, or you could have a lean running cylinder. Check your plugs, but the best way is to fix the exhaust leak and see if the problem goes away, I always say start with the obvious then go from there, its gotta be done anyway

Rejuvenated 1984 Interstate
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post #3 of 10 (permalink) Old 08-01-2006, 10:35 AM
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badleymans1000 wrote:
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I had recently acquired a 78 GL1000 & was told it needed some tlc to get it to run and it had to be put back together, for Free I could not complain cuz it is a pretty good bike still with 58,000k on it. I had finally got it running last night after spending a week freeing the floats in the carbs and cleaning them, but when it is running at a idol it backfires out the pipe on the one side, that same side also has a hole in the pipe before the muffler, would that have anything to do with it or do I have a diff problem I should be looking for.
badleymans1000 , that hole in muffler could easily be the problem.. As a rule the exhaust exiting the engine won't ignite in the muffler as it isn't in a combustible formbut if there is a hole or other opening that allows air to enter it could allow continued combustion (popping) in the muffler (depends on the exhaust pressure at time of popping).. Any negative pressure in the exhaust system will allow air to be pulled in through that hole..



Try plugging that hole & seeing if the popping stops.. If not look for a failing air cut-off valve or tightenginevalve..

Twisty

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post #4 of 10 (permalink) Old 08-01-2006, 11:26 AM
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WELCOME TO THE BEST GOLDWING SITE ON THE WEB!!

I thought I had cleaned my carbs good, got the throttle moving again and everything looked great. I had forgotten about the cut-off valves. Boy did that bike backfire. Anytime the engine was reving down after the gas was let off it backfired like some old hillbillies truck. I replaced my cutoff valves and presto, problem solved.

\'81 GL1100 Interstate
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post #5 of 10 (permalink) Old 08-01-2006, 12:42 PM Thread Starter
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Thanx guys for the help, I will check this out, unfortunate for me not till thurs.

Yamaha R1 sportbike rider that has been given
a Goldwing gift and loving it.
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post #6 of 10 (permalink) Old 08-01-2006, 12:48 PM
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Fortunately for you, there are a lot of knowledgable and helpful folks on this forum to help you out. Way to go guys!

Kurt

2006 1800 Titanium Audio/Comfort/Navi/ABS, past owner 1984 Aspencade, 1976 GL1000

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post #7 of 10 (permalink) Old 08-01-2006, 06:56 PM
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I had my GL1200 serviced at the dealer. When I started it up there, it backfired. When I got home, I noticed that the right exhaust had not been tightened completely. So, there was a gap before the muffler. I started it up again in the garage at home and BOOM! That was one of the loudest backfires I've heard in my life. I guess it didn't help that I was inside the garage. Anyway, I tightened the exhaust, which closed the gap and the problem went away.

I love my wife.

Suffering from Goldwing withdrawal daily since 2004.

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post #8 of 10 (permalink) Old 08-01-2006, 07:46 PM
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I also have a 78 that back fires only on one side when I let off the throttle and engine is reving down. Not to sound dumb but what are the cut-off-valves that you are talking about?
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post #9 of 10 (permalink) Old 08-01-2006, 08:20 PM
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The Air cut off valve is mounted to the front top right hand side of the Air plenum for the 1000. It can be found by following the vacuum hose from the bottom of the foward right hand carb. Tha cut off valve works whenthe engine is decelerating to enrich the idle circuits and prevent a lean condition to prevent backfiring. It is functional only under high vacuum situations created when theengine is decelerating. On the 1000 there is only one. I believe that the 1100 has one for each carb???

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post #10 of 10 (permalink) Old 08-01-2006, 08:31 PM
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Whiskerfish wrote:
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On the 1000 there is only one. I believe that the 1100 has one for each carb???
You are correct. I believe they are located on the right side of each carb body.

"Give me some wings I can glide upon" - Gordon Lightfoot

Bikes from previous lives...
1976 CJ360-T
1978 CX500
In Process...
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"Live Free or Die: Death is not the worst of evils" -General John Stark-

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