rd250lc rebuild

[rd250lcman]

Hi, have recently rebuilt my rd250lc for the track, it starts beautifully but once the choke is pushed in it only runs on one cylinder (the cyclinder without the choke carbie!) turn the choke back on and magically that cylinder fires right back up. Any advice?

[vifferman]

Sounds like it's running toldlessly lean - check for air leaks, blockages in the carb, and fur balls.

[rd250lcman]

I have checked all settings, now runs ok at 1/2 to 3/4 to main jet, once I allow revs to come back to idle that cylinder stops burning fuel. Again I start the bike with choke on allow to warm and it will rev right through the range through to 9k, oncle I allow revs to drop, after about 30secs the choke side cylinder start to not fire effectively.

[geoffm]

I have checked all settings, now runs ok at 1/2 to 3/4 to main jet, once I allow revs to come back to idle that cylinder stops burning fuel. Again I start the bike with choke on allow to warm and it will rev right through the range through to 9k, oncle I allow revs to drop, after about 30secs the choke side cylinder start to not fire effectively.

Blocked pilot jet and/or float height.

[smudge]

It will be very lean if it will rev out with the 'choke' on. Whatever is wrong should be pretty obvious, but check the outside before ripping into the carbs themselves. Check the carb balance tube - I think there may be a tube between the two carbs - not sure. Make sure that the hose connecting the vacuum tap is connected. Are you still running it on Autolube? If not you will need to have the oil feed holes into the intake blanked off. Have you done any mods to try and make it go faster????

If you find no air leaks and the carbs are ok there is a possibility that the crank seals are worn or something like the base gasket is damaged. More likely to be carburettor related though.

Dont ride it around like that or you may well melt a piston - just ride it long enough to see if you've fixed it.