Below is a pic of two heads, one I run and the other is a sprint head that just came back from tuning - both YPVS
The fresh and unused head is actually a reprofiled YPVS250 head from ole mailboxesetc that I got dirt cheap.
The question is that the squish on the new head is greater that that of the used head but look at the size of the chamber middles - it's kinda scaring me as it's over 1cm smaller and shallower
This will be an extremely interesting engine to run
Its an enormous squish.....but so is a stock 350....the theory now I believe has moved away from the old TZ large squish area to a narrower type.....not got any piccies of modern 250 race heads....shame.
Would like to see inside the latest GP125/250 aprilias.
Dunno if this is of interest. CR 125 1986 head, the bike runs like hell anyway. But i have no idea if it is the squish. Probably alot of small things working well together.
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It's no big deal, the grooves are not deep or anything. You don't think it's gonna be a problem do you? 