Another fuel concern - just need advise

[Jeffrey Matyas]

I have read every forum thread I could find about gas/fuel/corn/octane.
I decided to stop at the marina and pick up three gallons of "ethanol free" gasoline (91 octane) and then two gallons of 110 ethanol free race gas. The mix should workout to 98-99 octane. I am running Klotz benol at 32 to 1. It fired right up and I ran the bike (1979 KTM GS80 250) around the yard and down the street, felt great. Pulled the plug and it was brownish. Few questions; What do I need to look for as far as jetting and signs if the bike is running lean/fat? And do these bikes need leaded gas? (both boat and race gas I got was unleaded).
Edit- used a b9hs NGK sparkplug for reference.

Thanks for any words provided. - Jeff

[Daniel P. McEntee]

The best way to test your main jetting is to do what we came to call a "Rudder Run" after Dwight Rudder. You need a stretch of road long enough to get peaked  out in top gear, preferably heading toward your truck and tool box! When you hit that peak, clutch it in and hit the kill switch and make sure the engine quits right away, and coast to a stop with it clutched in. Then you can check the plug. It will read how it was operating at that peak on the main jet. If the main jet is correct, it will be that biscuit brown you saw. It will be whitish if it's toward the lean side, and dark or black if it's too rich. Oil mixture will affect this also. The reading you get and how the bike runs on your 32:1 ration will be different that on some of the concentrate oils out there that are in a higher ratio, some are claimed to be effective at 100:1. The more gas you have in the mixture, the more rich it will be and will need to be jetted leaner. I'm not a real active rider and racer these days, but I do try to put only alcohol free gas in my bikes, even regular 87 octain will run tons better and start easier that the the crap they force on us today, not to mention all the other problems the alcohol causes with tanks, petcocks, carburetors, etc. From your description it sounds like you are in the ball park, and just need to do a few "Rudder Runs." I would just decide on which gas you prefer to use, and avoid mixing, just for the simplicity. And as far as my experience goes, there is no need for leaded gas in our bikes.
  Good luck and have fun,
   Dan McEntee

[Jeffrey Matyas]

Dan, I seem to at least be in the ballpark. I don't mind mixing the gas as both stations are easy to get to and on the way home from work. I will give it a "Rudder Run" this weekend. Thanks for your reply!

[Daniel P. McEntee]

I have to drive almost two hundred miles to get gasoline with no alcohol in it! I have to go from north St.Louis county where I live, almost to Mike Winters house in Newton, Illinois! The station is actually in Effingham, IL and is the closest place I could find on the internet to get regular straight gas, so if I need to go see Mike or go anywhere near there, I take any empty fuel cans I have to fill them up. The bikes just start and run SO much better even at regular 87 octane. Just wish I had more time and opportunity to actually burn some !
   Good luck and have fun,
   Dan McEntee

[wfopete]

As to your leaded vs unleaded question; on a two stroke I can't see how this would have a significant impact on the motor.  IMO any lubrication/cushioning effect by the lead is more than made up for by the better two stroke oils available today. When unleaded first came out the concern was with four stroke valves and seat faces taking a beating due to the lack of lead.  There have been a bunch of studies on this.  I'm sure if you look around (or call a fuel manufacturer like VP), you can get a more detailed, accurate explanation than mine.

Pete Petrick
175 Jackpiner
Slow but Good

[brian kirby]

The highest octane unleaded fuel is around 103-104, if you got 110 you got leaded or it was oxgenated which is not good. Two strokes dont need leaded fuel but unleaded is limited in octane and is much more expensive.

Brian

[Jeffrey Matyas]

I found this on their website: "Research octane number is 116; motor octane number is 104 (R+M)/2 is 110 Reid Vapor Pressure is 6.6psi. Not Oxygenated and is not dyed." Basically they are using a lead substitute to get the 110 octane numbers. It isn't effected by sunlight like lead. I hope it doesn't attack my fiberglass tank? Guess we will find out!