Yanbansh04 Posted May 23, 2013 Report Share Posted May 23, 2013 I want to be sure what i will get with bigger compression, I have a new top end on my 7mil cub ( doing trail ) I have only 120lbs.. i know is too low, but i dont know the CC of my dome,they are not marked, its probaly 22cc, with 0.28 gasket, if I put 19cc dome with 0.20 gasket, how many compresson i will have ?, about 150 i think, but what i will win with bigger compression ? mid range or top end HP, thank you and sorry for my bad english.. Quote Link to comment Share on other sites More sharing options...
chevota84 Posted May 23, 2013 Report Share Posted May 23, 2013 More compression = more torque. 150 still isn't real high. Sent from my DROID RAZR HD using Xparent BlueTapatalk 2 Quote Link to comment Share on other sites More sharing options...
Abe Posted May 23, 2013 Report Share Posted May 23, 2013 What's your altitude ? Assuming 68 bore and unless your on top of the world id say that 19cc domes would be alky compression #s Quote Link to comment Share on other sites More sharing options...
Abe Posted May 23, 2013 Report Share Posted May 23, 2013 Also what kind of head do you have ? Most dome interchangeable heads use orings not gaskets Quote Link to comment Share on other sites More sharing options...
10milmike Posted May 23, 2013 Report Share Posted May 23, 2013 19 cc domes would not be alky comp, I have 180 psi and I run Vp 110, if u run 19cc and your comp is 150 I would run race gas.I know some people that set there bikes "10 dm" up for low comp 130 to 140 and run them on alky. Alot can change you comp, like port timings Etc alititude also plays a big part. My bike here in cali at sea level is 180, when I go to Utah it will drop to around 140. Quote Link to comment Share on other sites More sharing options...
Yanbansh04 Posted May 24, 2013 Author Report Share Posted May 24, 2013 Yes, 68mm bore, pro design cool head Quote Link to comment Share on other sites More sharing options...
Yanbansh04 Posted May 24, 2013 Author Report Share Posted May 24, 2013 But its too late, because i have buy the 19cc dome, but what is the mix of Vp you should to me, C12 is okay ? 1/3 Quote Link to comment Share on other sites More sharing options...
10milmike Posted May 24, 2013 Report Share Posted May 24, 2013 C12 is fine, I run mine 44:1 with no problems. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted May 24, 2013 Report Share Posted May 24, 2013 Take your current domes and CC them with a spark plug in the hole using water or even something like cooking oil. If you use a graduated cylinder or precision beaker you can keep track of how many CC's of fluid it takes to fill your domes. Once you know your current size, you can figure out what size you need. Rule of thumb on motors your size would be about 12-13 psi per CC increase/decrease Quote Link to comment Share on other sites More sharing options...
Nightmare Posted May 24, 2013 Report Share Posted May 24, 2013 I knew I had this printed out somewhere. Octane requirements by crank pressure are 130=92, 145=94, 160=100, 170=110, 180+=120<br /><br />Sent from my SGH-T679 using Tapatalk 2<br /><br /> Quote Link to comment Share on other sites More sharing options...
Yanbansh04 Posted May 25, 2013 Author Report Share Posted May 25, 2013 Okay, thank you all Quote Link to comment Share on other sites More sharing options...
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