Squish clearance.

[21bangbang]

Rebuilding a 29cc with a ESP head and 1mm longer connecting rod. Using the lead solder method, I measured my clearance at roughly .19thousands. Now from what I understand that is really not enough room for safe operation. The motor spins freely by hand, but I assume at WOT, im gonna smack the piston into the head. Worried about this I went to my local small engine repair shop for guidance. Long story short he said I would be fine. He builds competition chainsaws and was 100% confident I can run this motor. So just curious if any of you have run a very tight squish, and just how low did you go. Any issues? Did the higher compression effect power in a good or bad way? Heat issues? Appreciate any responses.

 

[pyroM!ke247]

Run it man. Especially if it’s the new kits ddm sells. There made to slap together and run. Last one I built was .17thousandths.

 

[21bangbang]

It is all from ddm. I guess worst case scenario I have to rebuild it again.

 

[Seandonato73]

Under normal conditions I wont go bellow 0.020" I've had saws I've done heavy port work turn out 0.015" or less. I normally shim for 0.020" never had an issue. 0.019" shouldn't be an issue. Theres more to squish then just the clearance till the piston smacks the head, but honestly we've covered this a few times now. I would assume these kits are made to be tossed on with a stock gasket, and I would also assume most people don't bother to check squish. So I'm sure there are guys with much tighter clearance then 0.017 or 0.019" and just don't know it.

 

[Stevendavis]

I'm also running an ESP head. Allan said I could go as low as .012 for more power. I'm at .016 and it's running great. I however don't have the long stroke conrod.

 

[Jshaff16]

@21bangbang and @Seandonato73 you two literally have already answered any question I have had regarding my dbxl...glad i can read and search the forums lol Wednesday my big bore kit will be here. Hopefully all goes well. First time for me