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09 YZ250F No start, but different this time?

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Hello guys,

I have a 2009 YZ250F. When i bought it, it hated starting. After some adjusting of the idle and air screw, she became fairly easy to start. I mean, what you would expect. 1-4 kicks every time, even hot. Anyway, on to whats gone on now.

I pulled the bike in my garage to clean it. Pressure washed it all off, cleaned it up, blew it dry. Now, it wont start at all. Not even trying to start. I am getting pretty heavy backfires out of the exhaust while kicking, not every kick, but frequent.

I pulled the plug, replaced it. Checked for spark, the ghetto way. Grounded against the frame but i have blue spark. I can smell fuel on the plug. Checked the air filter, its new and i cleaned it again to be sure. So my thought, maybe some water got in the pipe and effed a valve? Could it have jumped time overnight? Carb? I dont know where to go other than drag it to a dealer and get raped. 

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OK,  so here's what I've tried.  

Drained the carb bowl, drained the tank and refilled, checked for spark (have spark), pulled the valve cover.  Timing chain was loose because of a manual tensioner,  my fault I bought this bike used and never checked that. I shimmed the valves,  one intake valve is still too tight and I used the smallest shim.  Me timed  everything.  Still the same issue.  

I kick it and nothing,  I'll get a backfire out if the exhaust when I kick in that good compression stroke.  

Could I have clogged the starting jet or needles and coukd that be my issue?  Also,  I'm getting spark,  but if this CDI  box got wet,  coukd it be firing wrong in the wrong time? 

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Never had any issues at all with CDIs.  I have had issues with coil on plug.  But I would look for the simple stuff first since after you washed it you had issues.  You have spark, so no issue there.

Next simple thing to check is the hot start.  When you pull it, make sure it snaps back shut all the way and turning the bars doesn't change it.

Then, pull the carb and check the pilot jet.  If you can't see light thru it, it's plugged or might just have water in it.  Blow air thru it, and the passages .

Edited by ronbuell

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Thank You.  I'll make sure the hot start doesn't have issues.  I may just buy a carb rebuikd kit because it's an 09 and by the way it appears,  it wasn't treated well.  And at least I'll know all is well there.  I'll check back in then. 

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