Has anyone actually gotten and dropped one of those in a reasonably new stock cylynder, raptor or grizz, I'd be interested in the results. Whether it's fit is good enough to not burn oil and hold compression before a second breakin., paticularly if you had scuffing or heat problems. If I put the 10.1 to1 piston in my grizz I might want to add an oil cooler, some inline water coolers, and run 90'ish octane fuel. Lastly this might make a difference is whether the engine has to come out of the chassis to get the cylynder off the grizz. I didn't pay enough attention to that when I had it open for valve adjustment.

Elrancho~

I didn't get a drop in from HMF, so can't honestly answer that question. I can tell you that you don't need to worry about adding an oil cooler, inline coolers, would runner a better grade of fuel..but I always had anyways, and no, your engine does not have to come off the chassis. Just my experience from the 686 so far.

SilverBear

The engine "in chassis" is a good thing, perhaps I'll get in touch with HMF, they'll surely want to sell me one, hopefully I can pry some info from them too.