rebuilt kx won't kickstart

[limegreen94]

I just bought a 94 kx 250 with a blown piston, piece of the skirt broke off and jammed the crank. pulled the motor, inspected, cleaned the pieces out of the crank area, no damage to cylinder, put in a new wiseco. I tried to start it with the kickstarter, nothing. Took it out to the road and bumpstarted it, started right away. ran really good. great power, revved out cleanly, great. shut it down, still no kickstart. the engine turns over but it just doesn't catch. every once in a while a backfire. read 3 hours of info on internet then checked compression, 175 lbs, should be plenty right? pulled carb, cleaned main, and pilot jet, both were clean. changed the plug, still no improvement. took it out again for a good long ride. near the end of the ride it was down on power, won't rev out clean, lacking top end. will check compression again but what else could it be? I haven't looked at powervalves yet, air filter is clean, spark is healthy.  this is my first rebuild of a powervalve bike but have done lots of sleds and older 2 strokes, never a problem. please help.

[alward25]

Reeds?

[ylwgtr]

did you put new crank seals and mains?

[don46]

doubt it is the powervalve, if it was wrong it would start just not run right. I have had issues with the kill switch before maybe crank seals, if it was though I would expect it to rev high or smoke like a chimney. if it ran fine after you bumpstarted it I would lean toward electrical, for me, the fiorst thing I do is a new spark plug, you would be amazed at how many problems they clear up, four strokes to.

[Twosmokerfan]

Agree with electrical issues. I don't know about the 250, but one of my bikes had the adjustment plate for the advance out an it was a pig to start. I had to roll start it as I couldn't get enough engine speed. I ended up having it too far advanced.
TSF

[DoldGuy]

All good information....also check the float level, too much fuel in the bottomend & the only way to get it started will be to push it & it will cause the bike to run like a dog.

[limegreen94]

did not change crank seals, but no over rev condition, and just normal amounts of exhaust, haven't checked float heights, will try another plug.

[motopunk]

did not change crank seals, but no over rev condition, and just normal amounts of exhaust, haven't checked float heights, will try another plug.

thats definetely no sparkplug-problem!  look at the position of the stator-plate... it should be mounted with the middle of the 3 marks, that you could sea on top of the plate. and there is a mark on top in the stator-case, where you have to aline the middle mark on the stator-plate... 
after that, i will bet this bike starts with maximum 3-5 kicks... 

[don46]

if it ran great at first and then laid down, not a timing issue, could be a CDI  problem. Again change the plug, I don't care what anybody says for the few $ it is worth it, and contrary to what some might say, I have had funky spark plug problems and kicked myself in the you know what because of it.

[limegreen94]

fresh gas and a new plug and I have my hp back but still no kickstart, will check timing and change waterpump seals this weekend. (coolant/water mix in tranny oil) thanks for your help so far.

[motopunk]

if it ran great at first and then laid down, not a timing issue, could be a CDI  problem. Again change the plug, I don't care what anybody says for the few $ it is worth it, and contrary to what some might say, I have had funky spark plug problems and kicked myself in the you know what because of it.

agreed...just imagine that the timing marks on the statorplate are correctly fitted,  i think its the coil.
 try to get one and replace it. new coils you could find for 30,- dollar .always cheaper than a cdi in any condition and worth a try, before you replace the cdi.

your starting problem could also be fixed with a 1 or 2 steps bigger pilot-jet in the carb..