Valve spring seating pressure?
- Thread starter Hobot
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nortonspeed
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Said it before but as valve pressure shimming is an underestimated tune up I gladly repeat myself:
The only proper way to be sure using the right valve springs is to measure their pressure at rest (mounted in the head, aim for 80 - 100 ft.lb) and at full cam lift (aim for 180 - 200 ft.lb.) Too much pressure can distroy your cam and followers, too little pressure can cause floating valves at high revs. I have used springs from various manufacturers and their pressure can differ a lot. SHIM YOUR HEAD
The only proper way to be sure using the right valve springs is to measure their pressure at rest (mounted in the head, aim for 80 - 100 ft.lb) and at full cam lift (aim for 180 - 200 ft.lb.) Too much pressure can distroy your cam and followers, too little pressure can cause floating valves at high revs. I have used springs from various manufacturers and their pressure can differ a lot. SHIM YOUR HEAD
DogT
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When I had Leo at MMW rebuild my head, he stated that the spring pressure was measured, bud didn't give me a result. If you call him you may get an answer. Probably the guys at CNW would do the same. I don't remember it being in any manual I have.
Dave
69S
Dave
69S
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160 seated for a XR 750 . Bounce is bounceing of seat on closeing . Hence seating pressure required .
Float is Staying open , Followers Floating around , or actuateing mechanism , holding open / NOT following cam form .
Tangle , clatter , snap , rattle . OOPS . Full VALVE lift , + .040 + coil bound hight , = Fitted Length . Pressures as what may .
DONT belt Caps / keepers . THEY SHOULD ALL FALL TOGETHER < NO SNAGS > if they fitt correctly ( CHECK ) they require NO force .
A tap with a socket , across the knees to kick valve open & see collets ARE seated is usual . On the Bech if the Valve hits it , youve bent it .
NO , none , not any , Burrs , slag or wear in Keepers / colletts . Abraded polishing denoteing Wear . Fingers and turning collets & keeper on valve
feels binding rotateing , as it all fits perfect . Engineers blue would be a triple check . Check the Followers in the block ( cylinder ) are free
Dont Bottom ( Top ? ) fitted with no base gasket . Require clearnce past full lift . Possible ? for follower to be at limit of travel Before full cam lift .
SO THEY SAY .
Float is Staying open , Followers Floating around , or actuateing mechanism , holding open / NOT following cam form .
Tangle , clatter , snap , rattle . OOPS . Full VALVE lift , + .040 + coil bound hight , = Fitted Length . Pressures as what may .
DONT belt Caps / keepers . THEY SHOULD ALL FALL TOGETHER < NO SNAGS > if they fitt correctly ( CHECK ) they require NO force .
A tap with a socket , across the knees to kick valve open & see collets ARE seated is usual . On the Bech if the Valve hits it , youve bent it .
NO , none , not any , Burrs , slag or wear in Keepers / colletts . Abraded polishing denoteing Wear . Fingers and turning collets & keeper on valve
feels binding rotateing , as it all fits perfect . Engineers blue would be a triple check . Check the Followers in the block ( cylinder ) are free
Dont Bottom ( Top ? ) fitted with no base gasket . Require clearnce past full lift . Possible ? for follower to be at limit of travel Before full cam lift .
SO THEY SAY .
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