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Dremitchellyamaha

installed new top end and bike wont start

16 posts in this topic

I have a 2001 yamaha yzf426 that ran hot so I cracked a cylinder so I bought a top end(cylinder,piston, cylinder head) and installed it, cleaned carb flushed oil out and bike still won't start all I got was one loud backfire. I have checked for spark and its got spark, verified camshaft timing to crankshaft timing. And I'm going to check valve lash and leakdown test today. Any help would be greatly appreciated because I'm trying to ride by the weekend. Before I get stationed in ga.

Edited by Dremitchellyamaha

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lol yeah i agree, check the valve clearance. If they are too tight, you are getting too much effective overlap thus reducing your starting compression / efficiency. Also double triple check the cams are not phased incorrectly to the crank or each other. I screwed up once like that, the bike would fire if you bump started it, but not if you kicked it. It ran like crap down low and ran like crazy up high. Turned out we had the exhaust cam phased a tooth retarded.

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Ok guys here's the deal I rode the bike for about an hour and I parked it. When I tried to start it shown it wouldn't start. I pulled the plug and it was wet with coolant. I have a total of 3 cylinder heads and 2 cylinders so far none has worked. I checked two of the cylinder heads and they were warped so I have them being repaired at the machine shop at my school. What do you guys think the problem is?

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01 yz426

:busted: :busted:

Anyway, now that I'm awake, how did you go about torquing the head bolts?

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