2000 CR250R Problems...

[utrax42]

I just had my cylinder bored .020 over and got a new weisco piston to fit the new size. I had it all together and fired it up. It smoked way more than It use to even when it was cold. Its white/blue smoke and when I throttle it, it gets blacker. When installing the head I had torqued the head to 29 ft lbs on accident. So I had loosened them back to the 20 the manual calls for.

My question is this. Could my head gasket (metal) be damaged and be letting in coolant? Or possibly is my head warped?

Also. My carb dumps fuel out of the bottom fuel drain. If i turn the fuel off it stops, but will pour out again if I re-open it. Could my float be stuck? I just disassembled and cleaned it when I did my engine, and everything looked like new.

Thanks!

 

[mox69]

Fuel dumping out the bottom is definitely related to the float bowls. Either they are stuck or maybe your needle and seat are worn out. The floats could also possibly be set too high. Either way that is the problem area.


It's not uncommon (mandatory maybe?) to have to lean out the jetting when over boring an engine. As long as the coolant and transmission oil isn't disappearing the smoke can be remedied by re-jetting.


As far as the head goes. At a minimum i would loosen every nut and re-torque it. Whether you smashed the gasket or not is pretty hard to say. If it we're me I would probably just buy a new head gasket since they are cheap and easy to replace.

 

[utrax42]

My head looked warped today when I took it off and wouldn't you know it, I found a brand spanking new one for 68 bucks on **** so I bought it. Hopefully this will solve my problems. As far as the carb goes, do you think possibly a carb rebuild kit would solve the issues IF re-jetting doesn't work? I'll try rejetting tomorrow and we shall see. Thanks for the help!

By the way their is one more of those cylinder heads if anyone is interested.
Item number: 330121936330 New OEM Honda CR250R Cylinder Head 00 CR 250R 2000

Thanks for the tips, and I hope this link can help someone else out as well!

 

[mox69]

Well make sure you clean the carburetor while it is apart. I don't think a rebuild kit is necessary.

 

[Caseys500]

I just redid the top end on my wifes yz85...Got it all put together and it was dumping gas too...first thought was floats too. Took the carb apart cleaned and replaced...That's all it needed...no more fuel dumping and runs good! I wouldn't lean out a fresh top end either...If anything you should want it a little more rich because of the tighter piston/cylinder clearance. I would leave jetting as it is (if it was fine before) and mix gas with a little more oil than usual for the first tank, then back to normal.

 

[utrax42]

I have been running it extra rich. I also took the carb apart again and now have it installed but I havent started the bike, because I took the head off for when I get my new one. Thanks for the tips guys I appreciate it greatly.

A new question I have. The little exhaust valve or the power valve I believe it is called, It stays open when I push my bike in gear. By open I mean it is sticking down. I'm 100% positive the two little links are properly mated. Does it somehow only kick in at high RPM's? Thanks for the help, you guys are awesome!