MTC-piston clearence question

MTCs are forged and are a very good piston

that`s the reason why I bought these pistons.
But any engine builder or tuning shop here,I´ve asked about the piston clearence,told me the min. clearence should be 0.02 ".
Maybe anyone in this forum has the same parts and could tell me correct tolerances.

I'm sure they meant 0.002" clearance and not .020" clearance.

i use mtc pistons in all my bikes and ive never had a problem with any of them. in fact i have even got two sets that thru cylinder wear have gotin a bit loose in the bore igot them coated and am using them again, like i have said before i use them on the street i drag race with them and have done some hillclimbing with them and i wouldn't have any problem recommending them at all i have used other make's and have had good luck with those as well but i prefer mtc's the most important thing is that the bore is straight do some research on is the best at cylinder work and you should have no problems and the guy's at mtc are great to deal with if you any problems by the way i have 6 hot rod or race bikes. so i know what i talk about.by the way that piston inthe picture in the piston is 12-1 or bigger that is alot ocompression for the street,beautiful pistons aren't they though.

Yes I measured clearance, but where the valve contacts the piston I didn't and don't believe you can measure. It is at the outermost "eyelash" of the exhaust pocket. The valve will try to fold that eyelash over and at low rpm not 9k. Intake pockets were so close tolerance (within their tolerance) when i took head off to replace exhaust valve intakes were all a little to close for comfort you could see they have been just grazing the piston with a magnified glass on the piston. A little scary. AND NO head was just "cleaned up" by Greg Cope not cut down block is stock, and I have stacked copper base gaskets. When I was sent pistons I had 3 left pistons and 1 right also. Yes I know its just a spark plug relief but still. They were bought from Cope racing a while back, obviously. But just finished project this year but these pistons have been the reason I lost interest it project years ago... Just seems I souldnt have had to deal with all this BS..

Jd, Idle thoughts. 1st, unless oversize valves,bent valves,or piston slop, valves should nevet contact cut-outs.regardless of head/cyl shaving... valve contact to base of piston relief can be high lift cam, worn rod/crank,bearings,cam timing,incorrect pistons.having nothing to do with piston to cyl clearances.G

gane wrote:

Jd, Idle thoughts. 1st, unless oversize valves,bent valves,or piston slop, valves should nevet contact cut-outs.regardless of head/cyl shaving... valve contact to base of piston relief can be high lift cam, worn rod/crank,bearings,cam timing,incorrect pistons.having nothing to do with piston to cyl clearances.G

When you mill the head, you move the valves to the outside in relation to the piston. Valves can contact edge of the pockets.

What is the recomended piston to wall clearance for Wiseco pistons?
JD, When u added the extra copper base gasket to gain clearance what did u use for glue? did u have leaks?
i have a block that has been deck, and wondered wether a shim gasket would leak?

We bore Wiseco's to different clearances depending on a number of things. Some can be run as tight as .001.

Copper Coat on the base gaskets.

Jay

Thanks Jay.
What would be less leak prone? 1 thicker copper base gasket or a fiber plus a thin copper base gasket as a shim.(for the street.)and useing a fiber head gasket.

mark there is alot more chance of a leak if you use two gaskets as opposed to one thicker one cometic will build a base gasket to what ever thickness you would need, are you thinking of giving that block another try. by the way i use either spray copper coat if i'm taking the block of often and if it is there to stay i use GASGASCINCH icoat both sides of the gasket and the sealing surfaces on the case and on the block it is like a very high strenth contact cement. it is available thru bike shops that deal with parts canada i recomend it highly. once you bolt that motor together it shouldn't leak.

Thanks Tim.
I didnt know cometic would make a thicker gasket. i thought a thicker fiber would be more likely to sqeeze out. The fiber base gasket i have in now is trying to sqeeze out. i used ebond 1194 on it.
last year i had copper head and base, with Copper kote and it leaked.
I'm just getting all my options out . right now i would rather start over with a new block ,but if i could get a thicker base gasket ? The old block was decked about .025".
I think it would make too much compresion for pump gas?

Yes as Jay said, coppercoated all sides and no leaks. www.orientexpress.com seems to have a good selection of base gaskets, I'm sure others do too.