Nother 450 timing/topend question(sorry)


2 replies to this topic
  • bill petitt

Posted March 05, 2009 - 07:18 PM

#1

OK. Have a 08 yzf 450. It was bogging and had a little blue smoke. I decide it is time for a top end. Weisco. New gaskets, etc. Also new cam chain( other post now corrected. Thanks all)
Put everything together. and it feels like it has very little compression. Piston is nice and snug and rings are tight. Checked timing. Here is where the fun begins. If I have it at TDC(pencil in cylinder) The marks on the fly wheel do not line up. Off by about a 1/4 inch. So I time it based on TDC with the pencil and I put bot dots horizontal and flush with the head. I could kick it with no effort. Almost like the plug was out. So I do the timing again, this time by the manual, which shows the "I" mark on the fly wheel. Both dots flush on the cylinder. Same thing. NO compression. After about 10 kicks I got one big back fire. Thats it. I researched here and some one said put both cams off by one tooth? Is this with the fly wheel mark or TDC???( Yes the fly wheel went on the key and is tight) If I use the fly wheel mark, the piston is about an 1/8 of an inch down. One tooth off in which direction. I am assuming above the cylinder wall???
No compression?? The valves are in spec on both sides, with the middle intake a lil looser than the rest, but with in specs,(im thinking it was at 14 instead of 10)
Leak down test was done and everything is good. As I said, the last time it was running, my son raced it. Started up first or second kick. He said it had little power, especially in the deep sand corners. A little blue smoke.

All gaskets are new and everything is torqued. No leaks through the gaskets.
Any help would be much appreciated, as I have only 1 more day to get it up and running.
Thank you

Bill

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  • mitchicle

Posted March 05, 2009 - 07:27 PM

#2

When you timed it by the manual, did you stick your pencil in the spark plug hole to ensure you were at TDC? The reason i'm asking is(i am not sure on these engines but) you could be 180 out on your timing. Did you see any noticable scoring on the cylinder wall? The only other thing i can think of that would be the cause of that is a valve thats hung up. Sorry i can't be of more help.

  • grayracer513

Posted March 06, 2009 - 09:24 AM

#3

If I have it at TDC(pencil in cylinder) The marks on the fly wheel do not line up. Off by about a 1/4 inch. ...( Yes the fly wheel went on the key and is tight) If I use the fly wheel mark, the piston is about an 1/8 of an inch down.
Bill

These "facts" cannot coexist in the real world. If the flywheel were on the key, TDC would agree with the "I" mark on the flywheel. If you time the cams at actual TDC (which is correct), and the flywheel is not in the TDC position, the ignition timing will be off. You need to get to the bottom of this because it's where your problem lies.

I assume you realize there are 3 marks on the flywheel that look something like this:

|-| | <----- The third one is TDC, ignore the others.





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