gst_r Posted June 6, 2009 Report Share Posted June 6, 2009 i was thinking to run a mix of 50/50 of 110 race gas and 91 premium fuel this will be like 100 octane...but my fresh build have 130psi of compression and my timing is +4..after reading this i guess i should be fine just running premium fuel or can i gain some power running race fuel mixed with 91..?? Quote Link to comment Share on other sites More sharing options...
sheefreak Posted June 6, 2009 Report Share Posted June 6, 2009 i was thinking to run a mix of 50/50 of 110 race gas and 91 premium fuel this will be like 100 octane...but my fresh build have 130psi of compression and my timing is +4..after reading this i guess i should be fine just running premium fuel or can i gain some power running race fuel mixed with 91..?? No power gain. I would run premium pump fuel if I were you, quit wasteing your money. This is a tough question because I don't know of anyone that has wasted a motor experimenting to find out. Anyone care to donate one? :biggrin: Start at 160, beat the crap out of it. Disassemble, inspect.....reassemble at 170 and repeat. I have personally always just gone for the gusto. It is either stock ratio or 15:1 or so, so I just go straight to 110. Quote Link to comment Share on other sites More sharing options...
donkeypuncher Posted June 6, 2009 Report Share Posted June 6, 2009 i voted 185, but i meant to vot for 180 (mind was thinkin 180 hand clicked 185). i've always been told and read that 165 was the cut off for pump gas. im in the 155psi range on my bike and have no problems on straight 93 octane pump gas. but based on the 165 being the pump gas cut-off, i figured a mix of pump and race fuel should be good thru atleast 175 psi, so 180 is where i would start running straight race gas. but im pretty new to this octane vs compression thing so my reasoning could be off. Quote Link to comment Share on other sites More sharing options...
TeamRealtreeHD Posted June 6, 2009 Report Share Posted June 6, 2009 (edited) My bike was 185 PSI last year before I tore it down and it ran fine on 50/50... 116 with 93 pump to make 105ish That was a ported stock jugged, 17cc domed, +5 timing build at 1300 ft abl Edited June 6, 2009 by TeamRealtreeHD Quote Link to comment Share on other sites More sharing options...
brian Posted June 7, 2009 Report Share Posted June 7, 2009 I voted 175. I have run 50/50 mix at 165 with no problems. I think that would work at 170 as well. I figure that I am a lil more conservative than others though and I don't think that I would chance running anything but 110 at 175psi. Of course, when I was a young pup, I ran 110 at 135psi cuz I thought it was cool and was giving me more power. LOL Quote Link to comment Share on other sites More sharing options...
sheerider1026 Posted June 7, 2009 Report Share Posted June 7, 2009 I voted 165 cutoff for Prem. gas w/4 degrees timing. I have run 170 w/4 degrees timing BUT you have to have it jetted on the rich side, and you have to have GOOD Prem. fuel (out of a tank that has its own designated fuel hose , not a fuel station that has one hose does all three 87,89,93 etc. as you may get some of the 87 fuel that the last guy pumped out. Some other variables that come into play are squish band width/angle, dome shape, etc... but for the general answer 165 is cutoff. ^^ i'll have to agree^^^ many people dont beleive me when i tell them i am running 19cc domes, (aorund 163 psi) and +5.5 timing on 93 octane.. like jeff said, and i have argued before, running a little on the rich side, but it runs dam good.. 1 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.