Valve Piston clearance

[quad97]

Does anyone know what a safe valve/piston clearance is for a z400? I know how to measure, but I don't know how much clearance is safe for higher revs. 470 thumper racing big bore and putting in my old four stroke tech cams. They cleared with the four stroke tech piston but I figure I better check before i fire it over with the different piston. I do have a valvespring kit as well.

[soyo]

usually .060 in, .080 ex min. but .050/.070 still good.

you should be well within specs on that setup though.

[wilkin250r]

Originally posted by soyo
usually .060 in, .080 ex min. but .050/.070 still good.

you should be well within specs on that setup though.

Where is your information coming from?

It's been a while since I've done high performance work on a 4-stroke, but the number 0.100 in. sticks in my mind.

[soyo]

anything over that would be fine. these are as close as you can get with out cutting the piston or sinking the valves in the head. i have used a thin base gasket, milled .035 off the head and still have been within spec on the z400's. i would recomend using the valve springs though.

[400exrider707]

Originally posted by wilkin250r
Where is your information coming from?

It's been a while since I've done high performance work on a 4-stroke, but the number 0.100 in. sticks in my mind.


.100 is common with V8 builds that I've heard of.

I know Chad from DRG used to go much lower than that, but I dont want to put specific numbers out without knowing 100%.