Help What's causing this ?

[Anonymous]

I believe my bike is running quite well. The only thing that bothers the heck out of me is this = What I will call post ignition - I think. The symptom - In fifth gear - as long as I give it gas it runs strong - It is when I turn back the throttle to zero that I get a popping - pinging sound !
This will happen on other gears as I down shift>

I have a 1980 GS 1100 with 12,000miles, new plugs (splitfires ) also did this with NGK's. Bike has been running strong for 18 months - before that in storage for 16 years. The carbs were cleaned and synch'ed 16 months ago.

Please HeLp... Thanks

[Anonymous]

My bike is stock all around . Are there settings that I could adjust.

Thanks in asvance for your help !

[SqDancerLynn1]

Not sure of your noise? It sounds like you should make sure the cam chaine tensioner is working, you may need to resync the carbs again

[Anonymous]

I was concerned about the cam chain also - How do I test or tighten it ?

[Hap Call]

Does it sound mechanical in nature or does it come from the exhaust?

Hap

[Anonymous]

I have been trying to listen - my ear as close as possible to the engine.

At first, I thought it was exhaust related - Now I am not so sure. It is very predictable and sounds metallic.

I have changed fuel also from low test to high test - still sounds the same - although the last tank was 89 octane down from 93. and I think it had more noise. Again - not sure.

Thanks for responding

[Anonymous]

pinch wrote:

At first, I thought it was exhaust related - Now I am not so sure. It is very predictable and sounds metallic.

I have changed fuel also from low test to high test - still sounds the same - although the last tank was 89 octane down from 93. and I think it had more noise. Again - not sure

this is what i think is going on. especially since you had been running low test fuel. carbon will build up in your combustion chambers (quicker with low test)...then it gets cherry hot, and even though you let off the throttle, the engine is still sucking a little fuel in, and the cherry hot carbon is detonating the fuel, or spark knock. my bike was doing this under heavy loads, and when i took it all apart, the combustion chambers were gobbed with carbon. spark knock sounds like someone threw metal marbles into your engine...and it is very bad for the combustion chamber, I have seen it blow a hole through pistons if it goes on long enough. I suggest tearing the head off, cleaning everything very well. while you are in there, you can check the tensioner etc. and clean the carbs. It did WONDERS for my bike :twisted:

Ian