01trailshee Posted September 11, 2009 Report Share Posted September 11, 2009 what would be a safe dome size if im only running pump gas mixing 32:1 on a almost stock engine? 21 or 22 any help will be great thanx. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted September 11, 2009 Report Share Posted September 11, 2009 21's are fine and you can even add some timing, on stock stroke/cyl's Quote Link to comment Share on other sites More sharing options...
Overboost Posted September 12, 2009 Report Share Posted September 12, 2009 I run 20CC domes and just added +4 timing and its a blast. but I run 50/50 mix of 110 race fuel Quote Link to comment Share on other sites More sharing options...
AKheathen Posted September 12, 2009 Report Share Posted September 12, 2009 I run 20CC domes and just added +4 timing and its a blast. but I run 50/50 mix of 110 race fuel i actually run 20's, pro circuits, and +5.5 on 95 with stock porting and no deto. pulls hard as hell in the mid. yeilded less power with 100oct. Quote Link to comment Share on other sites More sharing options...
Overboost Posted September 12, 2009 Report Share Posted September 12, 2009 i actually run 20's, pro circuits, and +5.5 on 95 with stock porting and no deto. pulls hard as hell in the mid. yeilded less power with 100oct. HUH....when I went from 110 fuel to 93, my friend with the DS650 was able to pull on me by almost 2 full bikes I put in race gas, and we are dead even....have yet to race him with my new timing...my previous timing was -5...dont ask why...I just tore it apart and thats where it was... Quote Link to comment Share on other sites More sharing options...
AKheathen Posted September 12, 2009 Report Share Posted September 12, 2009 (edited) odd....it must have to do with the timing. when i ran 100, then went down it was after i set it to +5.5, and pulled the mid a bit harder. of course, I'm using av gas, which is formulated to atomize differently Edited September 12, 2009 by AKheathen Quote Link to comment Share on other sites More sharing options...
dajogejr Posted September 12, 2009 Report Share Posted September 12, 2009 Someone forgot to ask you the most important question. What elevation do you ride at? If you're at a higher elevation, sometimes even a 19 or 20 is fine. Second, Cranking compression does NOT dictate the need for more octane, compression RATIO does. NO fuel is rated for cranking compression. It is rated for compression ratio. Quote Link to comment Share on other sites More sharing options...
01trailshee Posted September 12, 2009 Author Report Share Posted September 12, 2009 I ride at about 800-1200 ft depends on the area. Quote Link to comment Share on other sites More sharing options...
Ieat4strokes Posted September 12, 2009 Report Share Posted September 12, 2009 I ride at about 800-1200 ft depends on the area. @Sea level to 600ft i was running 19cc domes on 93 pump with no detonation.......stock port. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted September 12, 2009 Report Share Posted September 12, 2009 Exactly...every motor and tune is different. That's why I say check compression ratio. It's math, you have some measuring to do, but it's not that bad. I consider it a learning experience as well. Quote Link to comment Share on other sites More sharing options...
Nor*Cal Kid Posted September 12, 2009 Report Share Posted September 12, 2009 What do you guys mean by "Detonation"??? Quote Link to comment Share on other sites More sharing options...
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