Jaystre Posted December 27, 2010 Author Report Share Posted December 27, 2010 ok so i ruled out the faulty gauge ... so how much octane is needed when running 190 psi of compression and do u calculate compression ratio? Quote Link to comment Share on other sites More sharing options...
Jaystre Posted December 28, 2010 Author Report Share Posted December 28, 2010 would not having a spacer plate under the cylinders change how much cranking compression i am getting ? because the port timing would be off. Quote Link to comment Share on other sites More sharing options...
bansheesrtoys Posted December 28, 2010 Report Share Posted December 28, 2010 (edited) well i am running a spacer plate under my jugs with no porting and 19 cc domes and i'm at 175psi and run 100 race gas stock timing .and it runs perfect. Edited December 28, 2010 by bansheesrtoys Quote Link to comment Share on other sites More sharing options...
Jaystre Posted December 28, 2010 Author Report Share Posted December 28, 2010 well i am running a spacer plate under my jugs with no porting and 19 cc domes and i'm at 175psi and run 100 race gas stock timing .and it runs perfect. are u at sea level or close ... i have 21 cc dome and 190 psi . where did u get those spacer plates?? Quote Link to comment Share on other sites More sharing options...
bansheesrtoys Posted December 29, 2010 Report Share Posted December 29, 2010 741ft above sea leveland the spacer plate came with my crank when i bought it. but i think vitoes will sell the plates by them selfs. Quote Link to comment Share on other sites More sharing options...
Jaystre Posted December 29, 2010 Author Report Share Posted December 29, 2010 741ft above sea leveland the spacer plate came with my crank when i bought it. but i think vitoes will sell the plates by them selfs. thx for sharing your setup info! at least i know im heading in the right direction Quote Link to comment Share on other sites More sharing options...
tedd1 Posted December 29, 2010 Report Share Posted December 29, 2010 What is the squish on this motor? Quote Link to comment Share on other sites More sharing options...
Jaystre Posted December 29, 2010 Author Report Share Posted December 29, 2010 ill have to check nothing change since the rebuild but ill let u know soon . Quote Link to comment Share on other sites More sharing options...
Jaystre Posted December 30, 2010 Author Report Share Posted December 30, 2010 What is the squish on this motor? squish is around .038 -.040 Quote Link to comment Share on other sites More sharing options...
tedd1 Posted December 30, 2010 Report Share Posted December 30, 2010 squish is around .038 -.040 Getting that up ~0.050" with a thicker base gasket would get you a lot closer to where you want to be. Quote Link to comment Share on other sites More sharing options...
Jaystre Posted December 30, 2010 Author Report Share Posted December 30, 2010 Getting that up ~0.050" with a thicker base gasket would get you a lot closer to where you want to be. yeah id like to run regular pump gas a lot cheaper and way more convenient ! you think a thicker base gasket would get me in the 150 ish psi range or it would not make that big of a difference? Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted December 30, 2010 Report Share Posted December 30, 2010 yeah id like to run regular pump gas a lot cheaper and way more convenient ! you think a thicker base gasket would get me in the 150 ish psi range or it would not make that big of a difference? Just so I'm on the same page here... You have a 4mil stock cylinder that hasn't been ported for a 4mil, and you're running a spacer plate on TOP of the cylinders, correct? If so, it sounds like you need to move the spacer plate to the bottom of your cylinders. That way it moves your cylinders up to put the port timings where they should be. Then try checking your compression again. 21cc domes at or around sea level should put you around 150 psi compression, stock porting. You could run 93 pump gas and advance your timing 4 degrees and be safe with that compression and squish. I would not mess with the thicker base gasket to adjust your squish. It'll change your port timings. Honestly, I think your squish is fine. I try to shoot for close to .040 Quote Link to comment Share on other sites More sharing options...
Jaystre Posted December 30, 2010 Author Report Share Posted December 30, 2010 Yep thats about it ! i bought this bike and it was all messed up as im going thru the rebuild im finding some weird stuff hehe ...but slowly i am making this right or trying too at least . ive ordered the spacer plate that goes under the jugs when it arrives ill install it and recheck compression . how can changing the spacer plate from top of jugs to bottom of jugs change compression that much ...does it have to do with port timing? Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted December 30, 2010 Report Share Posted December 30, 2010 Yep thats about it ! i bought this bike and it was all messed up as im going thru the rebuild im finding some weird stuff hehe ...but slowly i am making this right or trying too at least . ive ordered the spacer plate that goes under the jugs when it arrives ill install it and recheck compression . how can changing the spacer plate from top of jugs to bottom of jugs change compression that much ...does it have to do with port timing? Yes, it affects when the piston passes the ports. Putting the spacer plate above the cylinder basically just keeps your piston from smashing into the dome with the 4mil crank. The purpose of the spacer plate is to move your port timings up to match the 4mil crank, AND to keep the pistons from smashing into the domes. Being that your piston is not in the correct spot in the cylinder means it's not passing over the ports correctly and I imagine that would have an effect on your compression reading. Quote Link to comment Share on other sites More sharing options...
Jaystre Posted December 30, 2010 Author Report Share Posted December 30, 2010 ok thx a lot ! I will let u guys know what happens i installe the other plate ! do i need a gasket on both sides of the spacer plate or some black gasket meaker will be fine ?thx again to everyone for the help! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.