Y2K350 Posted February 14, 2022 Report Share Posted February 14, 2022 Looking for recommendations. Previous owner was running 30-1 oil fuel mix on 91 pump gas with an octane booster. Pulled plugs and they look to me like it was running way rich as they are black. Engine has been ported,polished and case matched. Old owner thinks that the domes in the cool head are 19cc. Main jet in carbs are 300’s. Exhaust is toomy t5. What are your thoughts????? Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
hoppedupandcutdown Posted February 15, 2022 Report Share Posted February 15, 2022 Octane booster is junk. And it will jack with the plug color. I run 20cc domes on 91 at 1200 ft about the same as you. 300 main should not be rich if you are ported, I'm not ported w/T5s and run 280's and I'm a little rich but don't foul plugs. Most run 32:1 or 40:1. Oil to fuel is not how you determine "rich" Just pick one and stick to it, jet accordingly I'd check the dome cc's for sure and not run smaller than 20cc on 91 Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted February 15, 2022 Report Share Posted February 15, 2022 I run 32 ounces of Klotz to 5 gallons of fuel. Never had an issue. Race gas 4mm Serval. Quote Link to comment Share on other sites More sharing options...
kawa110 Posted February 15, 2022 Report Share Posted February 15, 2022 32:1 Caster oilWeed eater with 87 octane and super tech to “race motors” with vpc12 and maximaSent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
Keno Posted February 23, 2022 Report Share Posted February 23, 2022 If old plugs, then who knows. Pretty easy to take the head off and check what domes are in there. SHOULD be scribed in the edge of the dome. Quote Link to comment Share on other sites More sharing options...
ClaudeMachining Posted February 24, 2022 Report Share Posted February 24, 2022 Check uccr, you dont need to remove head.Or open the head and check dome size.Envoyé de mon SM-N975W en utilisant Tapatalk Quote Link to comment Share on other sites More sharing options...
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