i just rebuilt my 250x engine after leting the chassie sit out side all winter. it starts by the 3rd kick when cold. once warmed up its a pain to start. somone said replace coil did that still doing it. i orderd a new cdi anything else it could be? not enough compression????

 

Id check the idle mixture first, if its too rich at idle, itll be hard starting warm.
When its a pain to start, pull the spark plug and check for spark, if you have spark, the coil and cdi are good. If you dont have spark, those old hondas were know for weak stators, and it shows up when hot. The core expands so much when hot, and after alot of heat and cool down cycles, the copper wires get brittle, and one ends up breaking. Then when it heats up, the wire has a gap, and an open circuit...it cools down and the wire retouches...and starts.
You can ohm check the stator, when its hot, and no spark. If its an open circuit....its bad. I think 100 to 300 ohms is about normal, but dont quote me on that, some one else should be able to give you the specs.
If it were compression, itd be hard to start cold too. But it wouldnt hurt to check it.

 

i had the same problem but never figures it out just bought a mikuni flat slide carb 34mm and big bored the engine got a pipe and air filter and proformance cam, proformance valves, bigger vales ported and polished and alittle bit more done 2 the motor total cost just for the engine was 2100 give or take a few bucks but i never been happier went with the 80mm big bore ans 13:1 COMPRESSION now its running with the 400's as in tieing in drags and trails.



sorry i couldn't help


(other modds besides the engine mods)

holeshot tires
dura blue +4 axle
Arms +3 on each side
lonesatar axle carrier
antifade lock nut
race cut finders
ac nerf bars
ac grab bar
DID O ring chain
14 tooth front sprocket
fly handle bars
pro kill switch
no air box lid

this thing Halls some taters!!!