What fuel i needed to run 12.0 compression? Will 101 Octane mix work without problems? Or 96-97 work?

 

The higher the octane the slower it burns. Higher octane is needed for higher compression to counteract the potential for pre-ignition, which is caused by excessive temperature in the combustion chamber that no liquid cooled system can disipate fast enough. High compression + low octane = violent combustion, resulting in the above.
I would definitely go with 101+.

 

I have a 702 pami with 11.2 to 1 conpresion with a little of Dons magic worked on the intake and exhause. the only way i could get my exhaust gas tempeture under control was to run 103 octane. when I ran the motor with 93octane had a ruff idel but you could not beat the top end would run real close to 1300 deg with amy main jet, preignition. You could not hear it in the exhaust and no motor knock.

 

Hey there Fredinpa, I ride at Tower City, PA ever here of it??

 

Hurycne- I am running 11-1 on super. But with the pro-port they say closer to 10-5 to 1. I figure it will be trail and error to see what runs best for the conditions.

 

Fred, are you sure you have the jetting right? The 11.2 should be fine with 92-93 octane fuel. Higher octain will help, but the motor is safe with premium pump gas.

 

How does the cam duration affect it? Can you run the pami piston and stock cams.

 

yes I have heard off tower city but do not know where it is. I'm located in north eastern Pa about 1 hr form Harisburg.

Don I'm getting close to have the jetting on. The weather is getting close to prime my main jet is 152 and i'm geeting a plug that is a little on the black side my pilot jet is 32 which is a little on the rich side and the reason I say that the mikuni manual states that if you back your airmixture screw out past 2 turns and it does not cause the idel to studder the pilot jet is too rich. but the weather is cool and I would rather run rich the lean.

The motor runs ok with the 93 pump gas and in a pinch to get back to the truck I would not hesatate to put it in the tank. but I like the way the higher octane responds at keeping the heat fluxation under control.

 

Fred -are you running the stock carb with the 703? I don't know your altitude but I haven't heard of anyone running as lean as you are. A 152 main is sure to contribute to overheating, I believe stock is a 165. hence the need for the higher octane?
What carb are you running???

 

That's cool Fred, I just wanted you to know that you were safe on 93. I know when you asked me to build it, you wanted to be able to run pump gas, and you can, without detonation. If you prefer the way it runs on higher octane, that's cool also.