99 YZ400F no compression


1 reply to this topic
  • SamuelJason

Posted January 03, 2015 - 08:37 PM

#1

So a while back I popped the head gasket on my 400. Replaced it with a new quality gasket at the same time I trued the surfaces, cylinder was un-marred but rings were replaced and gaps set to factory spec,replaced the cam chain, new plug, new oil, oil filter, set the timing, checked the valve clearances also while I was in there I checked the small and big end of the rod. All checked out fine. Well now after rebuild I can kick the bike over with out using the decompression lever the bike will cough a little but will not start. Carb was rebuilt and all passages were double checked to ensure no blockages. So any ideas of what could be wrong and how to fix? I'm stumped!

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  • yamahakid426

Posted January 03, 2015 - 09:29 PM

#2

Im no expert but sounds to me like you shimmed the exhaust valves too much and the exhaust isnt closing all the way on the strokes





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