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Discussion Starter · #1 ·
Hello all, New to the forum but been watching it and learning from you guys for a few years- So my story is I bought a 05 raptor 660 for cheap... ad stated highly modified BUT needs a clutch. Soo long story short I ended up putting in new/ used transmission gears in, new seals and rebuild the carb and the bike ran amazing for 3 seasons (I did hone the cylinder but reused the piston and ring at the same time)< dumb I know!! = burning oil. So here's my issue, I'd figure I'd get an wisco 11:1 piston and install it but noticed the timing chain had slack so might as well do a stage one hot cam and new chain while I'm there. Well... now the bike will not start again. It took awhile cranking it but it did fire up and ran for about 15 seconds and sounded/ran good but now I'm getting no start. Has strong compression, I verified the timing and decompression pin is spot on 3 times, gets a strong blue spark, and getting fuel, (tried starting fluid and gas in the plug hole and carb throats just incase and nothing but a backfire out the carbs). I set the valve lash @ .25mm exhaust and .20mm intake per cam card multiple times but doesn't even sound like it's trying to run. I also disassembled and cleaned the carbs a few times and nothing. Any help would be greatly appreciated!! Iam officially lost!

P.s after looking up the engine part #'s "highly modified" was just suspension work lol
 

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Discussion Starter · #3 ·
With the piston at TDC I installed the cam with the lobes down and the cam marks even with the head, I used a video scope down the spark plug hole to verify tdc and made sure the flywheel mark lined up. It definitely acts like the timing is off though!! When I would adjust the valves I set it at TDC and made sure the valves were fully closed. (I didn't check to see if it was on compression stroke or not if that changes things). Do you think it's possible the pickup coil/ pulser is sparking at the wrong time?
 

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Master of the Electron
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Are you sure that the timing is not 180° off, and that you set the valve clearances on the correct piston stroke?
Timing cannot be 180 off - the Raptor operates in 'lost spark' mode... so either of the two possible cam/pistion alignments work identicallly.

Valve adjustment, however, DOES require TDC of compression stroke... so make sure to be there prior to tweaking. The 'I' mark on the flywheel with both valves fully closed is the spot.
 

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Discussion Starter · #5 ·
Ok this might be a stupid question but I'm trying to think of anything at this point. Do you think it's possible that I need to re-jet it for the more compression and cam for it to start? I'm still running the stock 22.5 pilot jets and have 150 & 155 mains
 
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