Won't start cold

[Racer S]

i have a 2006 rmz250.  it has a new top end and valves with about 12 hours on it.  just recently it started to not kickstart when its cold.  it will start fine when warm.  also my choke wont stay on when im trying to start it.  whats wrong?

[x_JT_x]

Check the valve spacing? its possible that they are worn already. difficult cold starting is a sign of valve issues.

[MXWarrior323]

Valves moving, among many other things, is a common bad attribute with the 04-06 rmz250s as well.

[CLARKY06]

Like they said, i'd check valve clearance and your timing. I have the same bike, rebuilt the top end and have just split the cases to do the bottom.

My cam chain was worn, so the intake cam would jump a tooth, and one tooth out makes more of a difference than youd think, so might be worth checking your cam chain aswell. As for your choke, dont no, but its a good excuse to strip your carb down and give it a good clean. Incredibly simple to work on these bikes, and your problem can only be down to a few things, so just go through one at a time and im sure you'l easily figure it out.

[CLARKY06]

Forgot, and try not to listen to the people who will inevitibly comment telling you how bad these bikes are, everytime an 06 rmz thread pops up, like youv not heard it a million times before

[1987CR250R]

Most 4-strokes run such a small pilot jet that if they sit for more than a few months it tends to plug.  This will make the bike hard to start cold and not want to idle without the choke on.