Hi all,
I am not the type to ask for help but I'm about to drive my bike into a lake...
Back story and the problem:
I bought a 1982 GS850GL (19,000km) earlier this summer that had been parked since 1992. I was told it was 100% functional when it was put away and stored indoors for most of that time. This checks out with everything I've seen to date. I got the bike to the point where I can road test it and have been fighting this issue - when the bikes rev's to about 5K rpm under load it seems to bog down, almost as though it's hitting a rev limter. It will rev freely to the red line in neutral, the issue seems to only exist when the bike is pulling.
To get the enginer running I've done - in order:
-rebuilt the carbs - cleaned by pinesol dipping, and carb cleaner, new gaskets, and new pilot jets since I had to drill a couple out. I was not able to get the needle jet seats out so left the old ones in, new gaskets and O rings.
-fuel system was a disaster - tank was thick with rust, cleaned everything. New petcock. replaced all the fuel lines and fuel filter.
-bought a new foam air filter, all the old foam bits had turned to dust.
Test fire - bike ran like crap. I bought an ultrasonic cleaner and thought I'd redo the cleaning but more thoroughly - turns out the issue last time was some air box foam detached and jammed one of the carbs. But since I had the new cleaner I went through with another complete disassembly and cleaning.
Test drive - the bikes only rev's to about 5K rpm under load, almost as though it's hitting a rev limter. It will rev freely to the red line in neutral, the issue seems to only exist when the bike is pulling. As well when the petcock is in the on position the bike gets starved of fuel while driving but recovers when i switch to PRI.
I thought it seemed like a fuel flow issue - took apart the petcock, verified that the vacuum valve worked as it should - stumped. While in the PRI position there is tons of fuel flow.
Took off the carbs again - replaced the float needles and seats this time. Re-calibrated the float heights. No change to how the bike runs.
I then verified valve gaps were all within specs - they are (at the low end but above the spec). Also balanced the carbs. Plugs looked good but put in a new set. Still no change to the the WOT problem.
So now i'm thinking it's a vacuum problem since it seems like the main jet circuit is where the problem lies and it would also lead to the petcock problem. The bike starts and idles great, seems to be 100% until about 5K rpm and then turns to crap. I'm pretty sure the carbs are clean. I can't find any vacuum leaks. I really don't know what else to check.
Any thoughts from the braintrust at GSresources - not sure where to go...
I am not the type to ask for help but I'm about to drive my bike into a lake...
Back story and the problem:
I bought a 1982 GS850GL (19,000km) earlier this summer that had been parked since 1992. I was told it was 100% functional when it was put away and stored indoors for most of that time. This checks out with everything I've seen to date. I got the bike to the point where I can road test it and have been fighting this issue - when the bikes rev's to about 5K rpm under load it seems to bog down, almost as though it's hitting a rev limter. It will rev freely to the red line in neutral, the issue seems to only exist when the bike is pulling.
To get the enginer running I've done - in order:
-rebuilt the carbs - cleaned by pinesol dipping, and carb cleaner, new gaskets, and new pilot jets since I had to drill a couple out. I was not able to get the needle jet seats out so left the old ones in, new gaskets and O rings.
-fuel system was a disaster - tank was thick with rust, cleaned everything. New petcock. replaced all the fuel lines and fuel filter.
-bought a new foam air filter, all the old foam bits had turned to dust.
Test fire - bike ran like crap. I bought an ultrasonic cleaner and thought I'd redo the cleaning but more thoroughly - turns out the issue last time was some air box foam detached and jammed one of the carbs. But since I had the new cleaner I went through with another complete disassembly and cleaning.
Test drive - the bikes only rev's to about 5K rpm under load, almost as though it's hitting a rev limter. It will rev freely to the red line in neutral, the issue seems to only exist when the bike is pulling. As well when the petcock is in the on position the bike gets starved of fuel while driving but recovers when i switch to PRI.
I thought it seemed like a fuel flow issue - took apart the petcock, verified that the vacuum valve worked as it should - stumped. While in the PRI position there is tons of fuel flow.
Took off the carbs again - replaced the float needles and seats this time. Re-calibrated the float heights. No change to how the bike runs.
I then verified valve gaps were all within specs - they are (at the low end but above the spec). Also balanced the carbs. Plugs looked good but put in a new set. Still no change to the the WOT problem.
So now i'm thinking it's a vacuum problem since it seems like the main jet circuit is where the problem lies and it would also lead to the petcock problem. The bike starts and idles great, seems to be 100% until about 5K rpm and then turns to crap. I'm pretty sure the carbs are clean. I can't find any vacuum leaks. I really don't know what else to check.
Any thoughts from the braintrust at GSresources - not sure where to go...
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