Odd/ poor running once engine is hot.

[red_phil]

hi all.

My GS500ER seems to start up fine and runs great for about 15 minutes, but after that the engine runs a bit crappy.
Nothing too bad, just not as good as it is to start with.

Accelerating is fine but slowing or at constant revs the engine seems to occasionally missfire and just doesn't create as much power as it does when cool. Also a light rattle from the cylinder head develops as the engine warms up.

I adjusted the valve a couple of months ago, so they ought to be in spec.
It's got UK jetting so I have 40 pilots and something like 127.5 mains.
the mix screws are 3 turns out.

Any Ideas?

[scratch]

Everybody seems to be having trouble with their bikes now that the weather is warming up, even me.

[mjm]

Running worse hot is generally rich - since you probably have not changed the jetting I suspect a dirty air filter.

[red_phil]

well I checked the choke for sticking - nope.
Then I remembered my bike is restricted to 33 bhp (stoopid uk law)
apparently restrictors can make bikes run rich as they work by restricting air flow through the carbs. I Guess I'll back off the mixture screw as the problem does seem to be in the low throttle settings.

Hope this works, I'm off for a trip for 25o miles tomorrow morning.

[scratch]

I hope it works, and I hope you have a good trip!