250F 2003 yz250f not starting

snowflake

snowflake

1.) Valve Lash
2.) Compression test
3.) Pressure test the cooling system (ossagp has posted how to do this elsewhere, if you pressurize the engine through the spark plug hole you should not have air hissing at the radiator) this will tell you if you have a bad head gasket.
4.) Check timing, if the timing is off being hard to start would not be the only symptom, once it was running it would run very poorly.

and for the love of all things good make sure you didn't just leave a rag in the air boot :P
 
Peezy

Peezy

I will pull the head cover off again today or tomorrow. The bike starts right up now since i re-did the timing. I was reading that maybe the chain might be stretched a bit causing it to be off a tad?

There is a ticking sound when the engine is running. Starts in two kicks and now just this noise. My friend said sticking valve possibly.

I will open it up and check the specs again and a few other things. I don't think the valves have been touched since 03 lol.
 
A

AndrewWatt123

My 2003 Yz 250 2 stroke, i just did the top end, it blew up, rebuilt again this time new cylinder head piston rings, power valve cleaned and rebuilt. 1 kick and the bike would start. My son Rode it and said it was acting funny but rode ok? when i went out to check it out it wouldnt start. i kicked the shit out of the damn thing for 2 days. Cleaned the plug , made shur there was spark, cleaned the air filter. AND NOTHING!! It Seems like its not getting fuel ? So i opend the top checked the Cylinder, its fine. opend the power valve cover And it had kicked the 2 screws that hold the guides on the ends , Plus the center screw was off , all three screws were in the housing, along with the little piece in the middle, but it seemed ok. also the valves that move in and out , the one with the over spill hose was litterally pushed out of the hole. were i believe its machined together using a press ? i d k? just seems like it was,. by the way its made, any way my question are the valves getting pushed out to far? would the bike not start because the valve body wasnt operating properly? would riding it like that fry the rings? any advise would be awsome. thanks
 
2strokesteve89

2strokesteve89

AndrewWatt123:
My 2003 Yz 250 2 stroke, i just did the top end, it blew up, rebuilt again this time new cylinder head piston rings, power valve cleaned and rebuilt. 1 kick and the bike would start. My son Rode it and said it was acting funny but rode ok? when i went out to check it out it wouldnt start. i kicked the shit out of the damn thing for 2 days. Cleaned the plug , made shur there was spark, cleaned the air filter. AND NOTHING!! It Seems like its not getting fuel ? So i opend the top checked the Cylinder, its fine. opend the power valve cover And it had kicked the 2 screws that hold the guides on the ends , Plus the center screw was off , all three screws were in the housing, along with the little piece in the middle, but it seemed ok. also the valves that move in and out , the one with the over spill hose was litterally pushed out of the hole. were i believe its machined together using a press ? i d k? just seems like it was,. by the way its made, any way my question are the valves getting pushed out to far? would the bike not start because the valve body wasnt operating properly? would riding it like that fry the rings? any advise would be awsome. thanks
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Doesn’t need the power valve to start, maybe add some blue loctite to the fasteners this time. I didn’t see any confirmation of spark in your story, the kill switch, grounds, and spark plug boot are all easy things to check. If your worried about fuel, pop the spark plug out and add a squirt of fuel before a start attempt.
 
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