Left manual petcock on, now running issues

[ivany]

So have a 2000 GS500E, it's been running well for ~23 years. Never went into the carbs, haven't needed to.

About a decade ago I installed a manual petcock as I was having issues with fueling at high speeds. After a recent ride I forgot to turn it off, and only realized a few days later when I was smelling a bit of fuel by my bike.

Initially getting it started was a bear, I had to give it a bit of throttle and crank for ~30 seconds. It would run really rough and needed gentle throttle to keep it going. Once it got up to temp it idles OK, a little higher than before (1600 vs 1200?) but goes back to idle after revving.

Today I took it for a quick ride and noticed it was having lots of trouble getting above 40-50mpg going uphill. Felt like it was bogging. After 30 minutes of riding things got progressively better, no issues getting onto the freeway but it still feels like it bogs if I whack open the throttle at ~6K RPM. Mostly an issue at highway speeds (high load), not in first or second.

It does seem to be getting a bit better after putting some gas through it, but any idea as to what the  issue is? Gummed up main jets? And should I rip open the carbs or give it a few rides?

[Armandorf]

carb float needle sticking,  vaccum operated petcock prevented the flooding, now with manual petcock is evident because the carb floods even without the engine running.
You now have a carb float above level all the time. U clear tube  method from the carb drain.
You can try to hit the carb bowls with the handle of a screw driver  to make it close again, but will be temporary.

Clean the bottom of the carbs, needle jet inspect and replace, maybe its gunk.
The conical rubber should be soft with no edges or "steps"
While you are at it clean main jets.

[ivany]

Thanks! This has been an issue before for a long time (even a decade ago, if I left the manual petcock on for an hour, I'd have running issues for a bit).

Good news - started it this morning and it fired right up, responded to choke and idled as usual. Gave it a run on the freeway and looks like all of the issues I was having are gone. So looks like running fresh gas through everything for a bit cleared it up.

I know I'm going to need to go into the carbs at some point, but maybe not today 

[Bluesmudge]

For minor carb issues like that, you could try running some carb cleaner like gumout, seafoam, etc through a tank or two. Its possible its just a little varnish gumming up the carbs. This is exactly the sort of scenario where those products can actually work. Where the bike runs okay but not great after sitting. They don't work if the bike doesn't run.

[mr72]

BTW if it leaked fuel past the float needles while sitting, that fuel likely wound up going down the intakes and leaking into one or both of the cylinders and right past the rings into the crankcase. Do an oil change pronto. If there's an extra liter of fuel in there along with the oil then you will have too little compressible air in the crankcase and it'll cause running issues because the pistons are too hard to press down on the odd strokes.

[Armandorf]

BTW if it leaked fuel past the float needles while sitting, that fuel likely wound up going down the intakes and leaking into one or both of the cylinders and right past the rings into the crankcase. Do an oil change pronto. If there's an extra liter of fuel in there along with the oil then you will have too little compressible air in the crankcase and it'll cause running issues because the pistons are too hard to press down on the odd strokes.

In the centrestand i dont think that could be likely, it remains on the rear wheel with the front end pointing up so its against gravity ,it should leak through the air filter first.
in the side stand maybe.
Wath is the logic of the fuel going only to the intake side?, and also, where is the the overflow port, if there is one?

[mr72]

IDK the answers to any of that. I have removed the center stand from my GS, but have flooded the crankcase more than once with a dodgy petcock. Believe me, there was a whole lot of gas in the crankcase, and once I drained nearly 6 quarts from it!

[Armandorf]

I just remembered I left the petcock ON. Going to close it now.

Did you replace it with the newer model?  I have an 89
I'm using it like manual because the diaphragm is dead.

[Joolstacho]

An hydraulic lock will 'lunch' a motor in a second! At least take the precautions of draining the sump and removing the sparkplugs before turning it over.