12mm Posted January 24, 2009 Report Posted January 24, 2009 (edited) I just built a 4mil stock cylinder motor and i'm wondering where i should be on jetting the bike has vito 4mil crank PRO C pipes 34mm carbs 18cc domes fully ported cylinders also is it ok to run good 93 pump gas on 18cc domes ? right now i have 160main jets in there......and im at sea level. Edited January 24, 2009 by 12mm Quote
00tbanshee Posted January 24, 2009 Report Posted January 24, 2009 I just built a 4mil stock cylinder motor and i'm wondering where i should be on jetting the bike has vito 4mil crank PRO C pipes 34mm carbs 18cc domes fully ported cylinders also is it ok to run good 93 pump gas on 18cc domes ? right now i have 160main jets in there......and im at sea level. check your compression and see what you got i think 93 octane is probly not a good idea with 18cc domes. 158 mains 55 pilots with the air fuel screw leaned pretty good cel or cej needles i really like the cej's but alot of people run the cel's should put you relly close but always do a jet check and start rich Quote
12mm Posted January 24, 2009 Author Report Posted January 24, 2009 check your compression and see what you got i think 93 octane is probly not a good idea with 18cc domes.158 mains 55 pilots with the air fuel screw leaned pretty good cel or cej needles i really like the cej's but alot of people run the cel's should put you relly close but always do a jet check and start rich well if i mix it with 93 and 110 i should be ok then? and what damage can be caused by running 93 on 18cc domes ? Quote
00tbanshee Posted January 24, 2009 Report Posted January 24, 2009 i would do a compression test first then go from there.using the wrong octane will cause you to seize the motor up.could be pretty costly Quote
brian Posted January 24, 2009 Report Posted January 24, 2009 If the octane is too low it will cause detonation. Detonation will eat holes in the top of the piston. It's up to you if you want to chance that or not. Mixing 50/50 of the 93 and 110 will net approx. 101.5 octane. That may not be enough octane. You will have to check the compression to find out tho. Quote
12mm Posted January 25, 2009 Author Report Posted January 25, 2009 so if it's higher than 160psi i need race gas ?? Quote
brian Posted January 25, 2009 Report Posted January 25, 2009 Yeah. The real key to required octane rating is the compression ratio. Alot more goes into figuring the compression ratio than just static compression, however I believe that with any more than 155-160 psi I would run race gas to be safe. Check this thread out Quote
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