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Yardman lawn tractor valves


breakingorbit's Avatar
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Join Date: May 2006
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12-05-08, 12:56 PM   #1  
Yardman lawn tractor valves

Hi I was on here the first of November and was told my valves needed adjusted.Following the links I adjusted as described and had my Yardman running. . I used it 3-4 times now it will not start again. When I last tried to start it, it sounded like it backfired just by turning the key. I took out the spark plug and it cranks fine. The valves seem to work, my question is: when I turn the flywheel to check the valves they cycle top to bottom fine, but then I can turn the flywheel about 3/4 turn before they move again.Is this normal? i can't remember if it worked like this before or did something break on it. Hopefully nothing is screwed up. Any advice is greatly appreciated.
Thanks Orbit.

 
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marbobj's Avatar
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12-05-08, 01:15 PM   #2  
Well, for the most part it's normal. For instance on the intake stroke, the exhaust valve would be closed for about 180 degrees of the rotation. On the exhaust stroke, the intake valve would be closed about the same amount. Then on the compression/powerstroke both valves would be closed about 3/4 (give or take a little) of the flywheel rotation.

 
breakingorbit's Avatar
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12-05-08, 07:04 PM   #3  
Thanks! Glad I didn't screw something up.So I guess maybe the valves need tightened again?I haven't check them with a gauge yet,as I wanted to check this issue first.Any other advice is appreciated.
Thanks again
Orbit

 
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12-05-08, 08:26 PM   #4  
Of course the adjustment is important. If you have a tolerance set too tight it can cause problems as well.

I'm sure if you posted the engine make and model Cheese or someone here can come up with the exact clearance for you.

 
breakingorbit's Avatar
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12-08-08, 12:34 PM   #5  
Hi, I was given the clearance's by "cheese". It was .005 on both valves. That what I set them at, but this is the first time I have tried to do this. If they are too tight what happens? Do I just need to back it off just a little?
Thanks for the help.
Orbit

 
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12-08-08, 05:15 PM   #6  
If they are "too tight" then they are not set to .005". Recheck the clearance and make sure they are set to .005. If you still have a problem, post back and we can proceed from there. Make sure that you tighten the jam screw or nut so that the clearances do not change with a little run time.

Best of Luck...

 
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