I've recent picked up an 07 klx 250 after not having a bike for quite a few years and I'm loving getting back into it. I happen to have access to a supply of 100LL avgas so I'm wondering if anyone has some experience running leaded gas with these. I'm not too worried about it since there isn't anything downstream in the exhaust to foul, but curious if anyone else has tried this.

 

You'll get less performance with 100LL vs 93 E10..
Study the burn rates. 100LL burns much slower than lower octane fuels.
If you were to retune the ignition system (with much more advance everywhere) specifically for 100LL , you could get a power boost ..

 

it will work fine . especially in high compression engines. I don't think you will feel a loss of power, in vintage bikes you feel a gain. the slower burn gives you a longer "push" on the piston as the fuel is consumed. as mentioned, if you could advance the timing you could take real advantage of the power of TEL, but alas... too much work. unless you have a really big supply. it will kill a Cat, but you don't have one. last I bought was 5.50/ gallon (a week ago), all summer, it never got cheap like car gas. BTW, 100LL is very stable, it will last a couple years. these are things I know... almost 50 year in aviation as pilot & mechanic. more as a motorcycle guy

 

Yeah the stability and price (free) were my draws to it, I figured there might be a little wee drop in performance with big jump in octane but I'm pretty confident I wouldn't notice at my riding skill level. I've also been in aviation for 5 or 6 years now as an AME (just a pup still) so I can use whatever waste stuff we get that comes out of planes ( nice perk of job). Since I work with the stuff everyday I know it will work, I was more wondering what the long term effects might be and if anyone had done it long term. Excessive build up on the exhaust valve, leaving big deposits somewhere weird, fouling the sparkplug, stuff like that. These engines are new to me, I'm used to high displacement, low compression, low rpm ones that don't make all that much power for their size.

 

I'd run it in a heartbeat. pull the sparkplug at about 20 hours & have a look

 

I might have added that I'm second generation to a family owned/operated FAA registered private airstrip/airport..
Been using 100LL in motorcycles, 4whlrs, side by sides, jeeps, ranch trucks, tractors, - anything with a carb - for more than 50 years.. Far superior to any other fuel for keeping equipment reliable ( able to start immediately when needed)..

Never any negative issues.. 100LL WILL go "sour" , starting at about the 1.5 year mark in my environ.

 

Nice! That's good to hear, I've been running it a couple weeks now and didn't notice any difference really. Just nice to have a supply of good gas since I find the quality of gas to be hit or miss here in Atlantic Canada. Some carb tuning is definitely in order however, based on today's ride. Bogs and hesitates a bit with hard throttle inputs at low rpm. One of the previous owners put a DG exhaust on, jetted it and removed the airbox lid so I thinks it's running a bit lean based off what I've been reading on here. That's all part of the fun though!