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So what color are you guys plugs when you're are checking them running 100LL? I checked mines & they are grey.

 

That is perfect!! Dont let anyone fool you saying its lean. They dont know shit. Ledded fuel runs Light grey even almost a white when it perfectly tuned. Trust me. Your fine. Been running 100LL for YEARS

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That is perfect!! Dont let anyone fool you saying its lean. They dont know shit. Ledded fuel runs Light grey even almost a white when it perfectly tuned. Trust me. Your fine. Been running 100LL for YEARS

 

Thanks I heard the samething before from a member on here. I just needed a second opinion....I will run a second set of plugs with richer mains just to see if the color changes. Im hoping to see the grey get darker, if so I think I can finally read these plugs using this fuel from that. :headbang:

 

I have less than 155psi. with +4 timing, how much more compression & timing could I add to 100LL & be safe?....it's not a drag bike but more of a duner 421 cub. I should asking how much compression & timing was you running using 100LL for years?

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Thanks I heard the samething before from a member on here. I just needed a second opinion....I will run a second set of plugs with richer mains just to see if the color changes. Im hoping to see the grey get darker, if so I think I can finally read these plugs using this fuel from that. :headbang:

 

I have less than 155psi. with +4 timing, how much more compression & timing could I add to 100LL & be safe?....it's not a drag bike but more of a duner 421 cub. I should asking how much compression & timing was you running using 100LL for years?

 

 

I have the same set up. 22cc domes, +5 timing. I was wondering the same. I thought maybe 20cc domes max? But that may be asking for trouble. I wouldnt do less then 21cc domes on 100LL

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I have the same set up. 22cc domes, +5 timing. I was wondering the same. I thought maybe 20cc domes max? But that may be asking for trouble. I wouldnt do less then 21cc domes on 100LL

 

I tried some 93 pump gas yesterday & almost blew this engine. It started detonating, spark plugs backed out & right cylinder died & was smoking like a freight train. I turned it off & rechecked compression & it was 140-145psi. with the tip being 1/4" shorter than spark plug tip. So it has to have more compression than what the tester is reading. I'm also running +4 timing. I did not have any problems at all before I use 93 pump. So today im going to get 5 gallons of 100LL & see if it gets back to running good.

Edited by 252wheelieking
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I tried some 93 pump gas yesterday & almost blew this engine. It started detonating, spark plugs backed out & right cylinder died & was smoking like a freight train. I turned it off & rechecked compression & it was 140-145psi. with the tip being 1/4" shorter than spark plug tip. So it has to have more compression than what the tester is reading. I'm also running +4 timing. I did not have any problems at all before I use 93 pump. So today im going to get 5 gallons of 100LL & see if it gets back to running good.

 

 

YOur compression ratio will be around 14:1. 93 octane is for engine with compression around 11-12:1

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YOur compression ratio will be around 14:1. 93 octane is for engine with compression around 11-12:1

 

I pulled the head today & the right cylinder dome oring blowed & was letting coolant in the right cylinder. Everything stills looks good so im going to order a new oring kit put it back together & stick with the 100LL.

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Is the 100LL avgas rated at 100octane? Sorry if this is a dumb question. I head from a friend it is around 110 octane. Which is it?

 

No it's not a dumb question......From what I was told it's rated 100 octane...& I will be using it from now on....It is a damn good fuel in my opinion.

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I am going to make the switch to av gas as soon as I use up the fuel I use now. Right now I am using a 50/50 mix of VP C12 108 octane and pump gas 93 octane with koltz super techniplate mixed at 36:1. Should I use straight av gas 100LL mixed 36:1 when I make the switch?

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I am going to make the switch to av gas as soon as I use up the fuel I use now. Right now I am using a 50/50 mix of VP C12 108 octane and pump gas 93 octane with koltz super techniplate mixed at 36:1. Should I use straight av gas 100LL mixed 36:1 when I make the switch?

 

what is your compression ration & timing?

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170psi and +6 timing

 

Yes run 100LL straight....check your plugs after you switch cause it is leaded & oxygenated....you will most likely have to richen your mains 1-2 sizes.....after that you will like it... :cheers:

 

Oh yeah the plugs give a grey reading instead of brown....but you read them the same way....white is lean & the darker the grey the richer you are. Hope that helps.

Edited by 252wheelieking
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from everything i have read, 100ll is not oxygenated.

 

Also, depends on your gas provider, my local airport it is 108octane, im friends with the owner of the place.

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