Strm Trpr Posted June 7, 2015 Report Share Posted June 7, 2015 ^^^ that's am excellent idea. If the difference remains the same, then the problem is on the crank/rod combo. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted June 8, 2015 Report Share Posted June 8, 2015 Since it is a mono jug, the surface "SHOULD" be flat. Hard to imagine someone running a mill across that cylinder and not getting it right but I guess it's possible. Any way, given that every thing is flat, make sure the cylinder is torqued on to the base gasket evenly. If all that adds up, yank that crank and have it checked. Quote Link to comment Share on other sites More sharing options...
Coupelx Posted June 8, 2015 Report Share Posted June 8, 2015 You would assume so, but shit happens i guess. i dont know what rods andy started using on his cranks which was why i was curious. You really have 2 options, rods or pistons. Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted June 9, 2015 Report Share Posted June 9, 2015 I've been pressing cranks together for a lil bit now it's not unusual to have differences in materials , just the other day I had .003 diffrence in a oem rod. I have no way to know what years the rods are from but nevertheless there diffrent. It's also very easy while pressing shit together to have the center section not perfect or as your welding something for it to pull . I've had cranks pull .006 or better while welding . So I would check that crank , if you don't have the tooling send it back 1 Quote Link to comment Share on other sites More sharing options...
Strm Trpr Posted June 9, 2015 Report Share Posted June 9, 2015 ^^^ is exactly why I said one side can be +.003" and the other side be -.003". There can be an accumulation of tolerances between all of the interfaces. Think about it. 1) The radial distance of the big end crank pin to the crank axis can be off a little. 2) Use a degree wheel and find out how many degrees the crank pins are off relative to one another. This will affect ignition timing. 3) The center to center rod lengths can be off a little. 4) And the compression height of the pistons can be off a little. 5) Then throw in the fact that the crank will move some when it's welded. Having a matched set of rods and pistons is crucial... It'll be interesting to see what happens when the OP swaps pistons and rechecks squish. Obviously the OP knows how to test squish. This is for those who may be following. Here's an excellent explaination of how to test squish. http://rb-designs.com/rb_designs_llc_017.htm 1 Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted June 16, 2015 Author Report Share Posted June 16, 2015 Ok. So a quick update. I finally got around to screwing with the motor. I tore the top end off and flipped everything. I flipped over the base gasket, swapped the pistons from side to side, and swapped the domes side to side. Re torqued everything down and redid my squish test. I now have .039 on both sides. I don't know if it was something stupid like I didn't have the base gasket squished down enough or if just a slight difference in everything side to side made it off. But anyways, everything looks good now. Now I just need my domes recut to get my squish where I want it. Thanks to everyone who offered their insight Sent from my VS980 4G using Tapatalk Quote Link to comment Share on other sites More sharing options...
Strm Trpr Posted June 16, 2015 Report Share Posted June 16, 2015 Awesome!! What squish are you after? 1 Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted June 16, 2015 Author Report Share Posted June 16, 2015 After researching cheetah motors and talking to some people who have build them, it seems the magic number is .050 to .055 Sent from my VS980 4G using Tapatalk Quote Link to comment Share on other sites More sharing options...
Strm Trpr Posted June 16, 2015 Report Share Posted June 16, 2015 O, IC, thanks for the info! 500cc PV Cheetah, that's a beast! Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted June 16, 2015 Author Report Share Posted June 16, 2015 I hope so lol Sent from my VS980 4G using Tapatalk Quote Link to comment Share on other sites More sharing options...
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