wr400/426 turning crank with cams off


4 replies to this topic
  • roguemonkey

Posted October 10, 2009 - 07:32 PM

#1

This is probably a stupid question but ill ask it anyway. I had my cams off to adjust my valve clearance and noticed that when turning the drive shaft to find TDC it seemed a little easy to turn like it had lost compression and didn't need to use the decomp lever. Infact I had removed the decomp mechanism from the exhaust valve. Is this normal or might I have some bad valves or piston rings?

  • WR_Dave

Posted October 12, 2009 - 06:40 AM

#2

OK, I'll take a crack at this. You had the cams off and then were tryiing to find TDC? I would recommend leaving the cams in to find TDC so 1) you can see if the timing is OK or the cam chain is stretched. 2) so you don't run the risk of piling the cam chain under the crank gear. Did you have the engine at TDC before you removed the cams? If you did then it is possible that since the engine was at TDC that turning the crankshaft would allow the engine to turn easier becuase you wouldn't be compressing the air above the piston. This is assuming you were only turning the crank a few degrees on either side to line up the mark. If you were turning the crankshaft a few turns I would expect there to be some resisteance to movement from either compression or a vacuum in the combustion chamber. If you got no resistance in any way with the last scenario then I would assume a valve sealing issue or a piston ring/cylinder problem was what you should be looking at. I guess we need more info. WR Dave

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  • pablo83

Posted October 12, 2009 - 08:36 PM

#3

Did you remove the spark plug? That makes the engine turn easy.

  • roguemonkey

Posted October 12, 2009 - 09:25 PM

#4

Did you remove the spark plug? That makes the engine turn easy.


well the rest of the story is that I was turning the crankshaft because I had dropped the cam retainer down into the cam tunnel I was trying to see if it was stuck in the chain or anything else. Risky I know... However I didnt have a flywheel puller to get at it. I just noticed that as I was slowly turning the flywheel with a socket wrench I was able to make a complete rotation without using the decomp. There was resistance but it didnt seem as difficult as it would be to push through the comp stroke with the kick starter. With the kick starter I can pretty much stand on it and it wont kick through without the decomp lever, I wieght 210LBS . But with the socket wrench at the crankshaft I could pretty much turn it through the comp stroke with one arm with some force ofcourse. My guess is it may be time for a piston ring job or just simply that I had more leverage at the crank shaft... Not sure. Its a 99 wr400 with about 1300 miles...

what do you guys think?

  • pablo83

Posted October 13, 2009 - 07:40 AM

#5

well the rest of the story is that I was turning the crankshaft because I had dropped the cam retainer down into the cam tunnel I was trying to see if it was stuck in the chain or anything else. Risky I know... However I didnt have a flywheel puller to get at it. I just noticed that as I was slowly turning the flywheel with a socket wrench I was able to make a complete rotation without using the decomp. There was resistance but it didnt seem as difficult as it would be to push through the comp stroke with the kick starter. With the kick starter I can pretty much stand on it and it wont kick through without the decomp lever, I wieght 210LBS . But with the socket wrench at the crankshaft I could pretty much turn it through the comp stroke with one arm with some force ofcourse. My guess is it may be time for a piston ring job or just simply that I had more leverage at the crank shaft... Not sure. Its a 99 wr400 with about 1300 miles...

what do you guys think?


I'd do a compression test before pulling it apart.




 
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