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I am a new owner of a raptor 660. Now what I need the help with is: EVERYTHING!! I had to put the top half of the engine back together. I go to crank it up the first time, I got a couple of putters and that was it. After that, It sounded like it backfired through the carb and the exhaust a couple of times. I pulled the carbs off and put a little gas in the intake boots, still nothing. I checked the spark, it has a strong blue spark. I lined up the timing marks by the manual. Still nothing. I am a total idiot to four wheelers, thats why I bought a manual. Hand me a Small Block Chevy, now we're talkin! So any info no matter big or small it is will be greatly appreciated. Just a side note, I had to put a cam and a head on it; I threw a set of rings on it while I was in there. It has great compression also. The jug was in great shape, no scratches. Also the choke doesn't work, It's missing a couple of pieces off that. Also does the timing marks on the cam gear line up PERFECTLY to the head or is one of them off just a TINY BIT. And someone that has done timing before, please tell me exactly how you did it, just to see if I did it right. Thanks Again In Advance!
Def check the valve clearances and check your timing again. I just went through all of this crap on mine. It wouldn't crank so I removed the head to inspect the cylinder. All that was fine, I re-installed everything, set the timing and it still wouldn't start. It would pop a few times like you said, I had fuel, good spark, and compression - still nothing. I took it to my mechanic and he said the valves were too tight and the timing was off. I didn't understand the timing, I double and triple checked it according to the manual. He said I lined up the wrong dots? I thought I did it like the manual said. Seems the 660 has a sensitive timing setting.
I ride, because football, basketball, and baseball only use one ball
The timing can be tricky because there is a little play in the chain, especially without the cam chain tensioner installed. Re-check with the tensioner installed. If it still looks right and it doesn't run move the cam sprocket a tooth and try again. If the doesn't work move a tooth the other direction and try again. I've had to do this and that did the trick for me.