High Octane Fuel

[john durrill]

Don't know if this will help anyone , or if its already know by most. A good source for fuel for Pentons is 100 octane low lead aviation gas. It can be gotten at most small
airports. it keeps well. It was the only thing that work well in the 79 400 KTM I restored.

 

[skipperclyde]

I suggest you read the forum on Octane Boosting before using Aviation Gas

 

[Chris Brown]

Gee John,
Mine runs fine on pump gas! Will probably go to 20% race fuel to insure there's no detonation. And I run Golden Spectro at 50:1. Top end after about 40hours still looks like new. Just a little carbon under the rings and on the piston dome. Have re-jetted for a cleaner burn and to eliminate the mid-range burbling. Bing agency was VERY helpful.
Chris Brown

 

[john durrill]

Thats good to hear Chris,
 I always wondered if 50 to 1 would work ok in Penton. I had good luck with Bings also.
They responded well to jet changes , Predicably would be a better word I guess.
 Wonder if the old 98 octane was a different way of measuring than the method used today?
 Hope some one knows the answer to that. By the way Chris what size Penton are you running?
 John D.



Edited by - JOHN DURRILL on 09/24/2001  8:15:28 PM

[Chris Brown]

It's the white 400 in the featured photos section.
I've put over 500 miles of trailriding on it since the new top end (complete resto). I tore it down recently and everything was still like new inside.
Talk about power! I used to ride a Six Days when I was a kid. I consider the 400 the epitomy of the design. Very light and fast! Mine tips the scales at 232 with half a tank of gas. My 92 CR250 weighs that much, and not nearly as manueverable in the tight trails. In the desert the 400 would smoke it. That is, until you hit the wooped out sections.
Chris

BTW, race gas will make it run cooler. Can actually reduce power as it is slower burning. Octane ratings are done the same, we just get poorer grade fuel. AV gas is loaded with additives, NOT good for your bike motor.
I've ran 50:1 for quite awhile, then went back to 40:1. Discussing the issue with my race tuners they said no way, go back to less oil. Golden Spectro does NOT burn. It's synthetic. As long as you're getting some oil through it's lubing the motor. The gas is what cools it, not the oil. I had to lean out the main jet to clean it up. Now the plug is the right color. That's the only true indicator.

Edited by - chris brown on 09/26/2001  12:46:29 AM

[john durrill]

Sounds good Chris,
Found out the same thing about more oil or less oil in the 70's. I makes sense when to think about it. 20 to 1 has less gas metered in a given amount of time than 50 to one. Your 400 sounds a lot like the one
1 restored. Rode with a bunch Of Honda guys on cr's. In the tight stuff they were amazied a 79 could go so fast in the woods.
I must have been lucky with the AV gas I got, given the response on hear. Think ill just find a source for race gas around hear and do what Larry and you suggest. Mix it up between 50/50 and 25/ 50 and see how it goes.
 THANKS for every ones input,
John D.