Baffled

[Hodado]

Thought I had my 650g figured out;I was wrong.Runs fine up tp 4-4500rpm,then bogs out.Have had carbs out 15 times[at least] new rebuild,new o rings new pilot,and main jets etc etc,suspected coils;had them tested was told they were fine.what next?I was told the cdi box either works or doesn't.The bike starts,idles fine no miss, runs on all cylinders.Can anyone tell me what compression should be ?
Thank You

[miked]

compression numbers should be within 10% of each other across all cylinders, the higher the better. what are your numbers?

are you running the stock airbox? stock jets/needles in the carbs?

not enough info to help you yet

[tom203]

Thought I had my 650g figured out;I was wrong.Runs fine up tp 4-4500rpm,then bogs out.Have had carbs out 15 times[at least] new rebuild,new o rings new pilot,and main jets etc etc,suspected coils;had them tested was told they were fine.what next?I was told the cdi box either works or doesn't.The bike starts,idles fine no miss, runs on all cylinders.Can anyone tell me what compression should be ?
Thank You

Carbs out 15 times! Bogs out- instantly? or in a minute. Make sure petcock can pass enough fuel; also make sure tank vent ain't plugged. This is mid rpm range,where main jet/ needle are taking over.

[hikermikem]

What do your plugs look like??

Next time you have your carbs out, look inside the needle jets & make sure they're not all pitted & corroded... I had that issue once & it took me quite a while to figure it out - one plug was always black because the needle jet wasn't metering the fuel correctly, due to the "extra holes" that allowed the fuel to go around the jet needle.

Here's that thread, good pics start around post #44

http://www.thegsresources.com/_forum/showthread.php?t=132691&page=2

[Hodado]

Stock airbox,Will check compression.When I say bogs out I mean it won't make any more rpm; it doesn't stop running.almost like a rev limiter.Where is tank vent??
Thanks

[1_v8_merc]

Your not running an inline fuel filter are you?
I had the same problem once, and was due to a filter I was using.

I switched to a larger diameter one, and problem gone.

[Hodado]

no,I am not

[Nessism]

No personal experience but some people here have reported similar issues when their ignitor box started to fail.

[Hodado]

I hate to buy one and find out I didnt need it.I don't imagine they can be returned

[tom203]

Stock airbox,Will check compression.When I say bogs out I mean it won't make any more rpm; it doesn't stop running.almost like a rev limiter.Where is tank vent??
Thanks

Good question! I don't see a hole on mine, so it must be under flat gasket on tank cap. If your fuel level is low, temporarily remove this gasket and see what happens, but I don't see how this would be consistently at 4500-5500 rpm's. Have you inspected your ignition advance system-those liitle spinning weights behind signal generator coils?

[SAN]

Baffel

Had same problem 81 gs550TX spent many hours.Eliminated fuel issue.Does it do it if choke is out? My problem was cured with a Dyna S. I asumed the problem was Pick ups for igniter. good luck

[Hodado]

Yes I have checked the weights; the jaws open as you rev it up.Have to borrow compression tester yet.

[tom203]

Yes I have checked the weights; the jaws open as you rev it up.Have to borrow compression tester yet.

Any conclusions???? if compression is reasonable, has to come down to a erratic ignitor like nessism said. You would think they should just fail, but maybe they limp on.

[Hodado]

Where should I look for best price on ignition;and coils,? Hate to replace but everything is 30 years old.If it's not the issue now its only a matter of time when it becomes so

[tom203]

Where should I look for best price on ignition;and coils,? Hate to replace but everything is 30 years old.If it's not the issue now its only a matter of time when it becomes so

Member blowerbike deals with these ignitor things (or used to). If you want to try to substitute a different ignitor and see what happens- send me a PM, I have two spares, but untested . I could send you one to try out. model #32900-34210.
They surface on ebay regularly, sometimes strippers think they are R/R's and not ignitors.

update: I sent PM later