kevincurtis Posted August 28, 2013 Report Posted August 28, 2013 I just recently got my 421 together, I'm running it with pump 91 octane with pro design cool head and 24 cc domes at sea level. i did a compression test today and my compression raised to 160 psi after break-in, i know its quite high for 91 octane, and my timing is still at 0" I want to advance it 4 degrees.. i'm thinking I'll have to get some custom domes to run pump fuel, but if i was to run a higher octane what would you's recommend i run ? just curious because this is my first time playing with my bike with the compression bumped up, Any info would be great thanks ! Quote
Surfrjag Posted August 28, 2013 Report Posted August 28, 2013 sounds like a 110 and 91 mix might be for you. you would really have to ask the person that made the domes Quote
mike0chek Posted August 28, 2013 Report Posted August 28, 2013 pretty sure bumping you timing up will only make your high compression worse. what is your current squish?? Quote
mike0chek Posted August 28, 2013 Report Posted August 28, 2013 im running same domes and elevation as you with a similar setup on 91 pump with 140 psi compression. squish is .053 Quote
kevincurtis Posted August 28, 2013 Author Report Posted August 28, 2013 pretty sure bumping you timing up will only make your high compression worse. what is your current squish?? My current squish is .042, I'm using Vito's 13 degree dome angle domes. Squish is within spec Quote
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