need help before i take it to a stealership

so i have a 04 yz250f. two weeks ago i put new valves, cam chain, and piston in it. so i broke it in last weekend, about half hour of 5 min heat cycles, and then this weekend i went to the track and the bike was great starting first kick and rode for about an hour and the after a break i went to kickstart the bike and nothing, it didn't even sound like it wanted to fire. so i tried bump starting it and nothing. I ended up loading up and going home. when i went to try and start the bike at home it felt seized because the kickstarter wouldnt move. i pushed it down the driveway and jump on and let the clutch out and it started turning over again and when i kicked it over it felt normal again but it still wouldn't fire so i pulled the spark plug cap and looked down the hole in the cap while i kicked the bike over and couldnt see any spark. so then i checked the killswitch but it looked normal. any help is appreciated

We might need to know more: getting gas, etc. But for starters, if NO spark then NO start, address that first. Im curious about your spark-checking technique, make sure you do that right; the spark has to be grounded, ie against the head or something.

How did it run before shut off?

it ran perfectly before it shut off. I just rode to the car for a break and shut it off. went to start it 5 min later and nothing, didnt sound like it wanted to start so i tryed push starting it and nothing. it is getting gas and is there any way to check for spark. I tryed sticking a piece of metal in the sparkplug cap and touching it to the cylinder and then touching it while i kicked the bike over and didnt feel and spark. I also tryed it with the killswitch unpluged also

Sounds like a bent valve or possibly a damaged ring.

Checking the valve clearances will give you a clue if its a bent valve. I am leaning towards that since you just put them in.

nope just checked the valves a min ago .010 on all intake and .020 on all exaust

hold the spark plug to the head and kick it... as a tip turn off the lights. if there is a spark u'll see it, if not, move it around to make sure it's really grounded and try again... still nothing put in a known good plug and try agian.

Thats good then. The only way I think it could be electrical is if a wire melted through because it wasn't routed quite right. I have had kill switches go bad, so unhook it and see if it starts.

Usually the best thing to do in these situations is to just start pulling the head off. Normally you will find the problem in the process.

ok the only reason I thought it as something outside the engine was because of how it went from running perfect to nothing

That sentence about the kick starter not moving seems like a pretty important bit of information.

yeah well after i pushed the bike with the bike in gear it started turning over like normal but do you think the rings didnt seat properly?

I don't think it would have ran very good if one of the rings broke. The kickstart not moving is what lead me to believe bent valve. I am still thinking that may be it. It doesnt take much to bend them slightly.

ok so i went out and stuck a screwdriver in the spark plug cap and kicked the bike over and felt a good zap so im going to buy a new sparkplug tommorow and go from there. and how would i have a bent vlave, the timing is dead on

I don't think it would have ran very good if one of the rings broke. The kickstart not moving is what lead me to believe bent valve. I am still thinking that may be it. It doesnt take much to bend them slightly.

theres an easier way to check if u have a bent valve than pulling the head off the bike... do a compression check... its better than pulling something apart and finding out nothing was really wrong...

When you had trouble kicking over sounds like the auto-decompression mechanism stuck, which can happen on these bikes. If the timing is right, the valve clearances are right, and it is getting the right amount of fuel then it is probably an electrical issue. Try a new plug first and go from there.

ok so i went out and stuck a screwdriver in the spark plug cap and kicked the bike over and felt a good zap so im going to buy a new sparkplug tommorow and go from there. and how would i have a bent vlave, the timing is dead on

what does the old plug look like?

Alway start with a new plug FIRST..... 99% of all problems is the plug

did you over torque the cam cover, did you put those c clips in(i dont the symtoms of not doing it, but always the possibility) did you torque all bolts to spec in the process of rebuiliding the bike

whats the method of checking spark you do, what i do is have the sparkplug that you think is causing problems, ground it to the head and turn over the bike at medium or slow speed, try a new plug using this method if thats no it its probably something to do with the electrical system

but the kick starter not moving is a whole other story in itself

maybe do a compression check to see if one of the valves is bent in the open position or to see if the rings are bad

maybe do a compression check to see if one of the valves is bent in the open position or to see if the rings are bad

He already said the valve clearances are all correct. If a valve was bent then the clearance on that valve would be excessively large.

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