Author Topic: Deck Height Difference in XT Cases Versus XP Cases  (Read 829 times)

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Offline weimedog

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Re: Deck Height Difference in XT Cases Versus XP Cases
« on: May 06, 2014, 01:14:36 pm »
I just put a mako 272 and Jinhua piston together with the wrist pin. was approx. .052 difference in crown height. If the cylinder is like the last one..... big if....  with no base gasket it was .032 squish. So one base gasket would get me to that .052!  A .040 gasket/shim is needed to get that 272 piston to .020 squish.. So there is hope. On the other end there is approx. .115 in difference in skirt height. that translates between 5 and 6 degrees difference on intake timing. Take a gasket moving the cylinder up .040 or loosing a couple of degrees and we are in the ball park. 76- 2 (gaskets)= 74 degrees...then with the .115 in shorter skirt, approx. 6 degrees... that a net 80 degrees btdc. So net net net the other cylinder & piston & .020 stock gasket had .052 squish & approx. 75 degrees btdc....  With the 272 Mako piston & .040 gasket/shim? looks like it might end up close to 80 degrees btdc intake timing and .020 squish.  Of course the other differences would be the windowed piston & change in exhaust & transfer timing, but no change to its large 27 degree blow down ... maybe cutting some material at the base of the transfers,( the cylinder wall away). Might make a mess but also might be an interesting build.

Also did the same thing with a Stihl (Meteor am) 064 piston with interesting results! Only .010 more distance to the crown but the piston skirt was actually longer than the Jinhua piston.....buy .010 Real interesting.. Maybe those Jinhua Farmertec folks know what they are doing? Going by the "old Jinhua (Huztl saw) cylinder, that .010 would in fact get me to .020 squish and it would be easy to grind the intake port lower to get the intake closer to where we want... I think an easier path to an interesting AM build. And the Stihl (Meteor) is also a windowed piston. Also have a X-torq carb, those things along with a muffler with a 3/4 inch pipe should run well. And Loud!

Am I way off???

But back to the 350 build. (modified transfers (hogged out dividers on the vertical section & matched the lower to look like a 346xp both on bearing cap& cylinder), muffler mod, intake lowered, 357xp carb & intake tract. )


 

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