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100LL In 2-Stroke

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I work at an airport, and can get 100LL cheap, and I was wondering if anyone else has tried to run it in their 2 stroke.

I've used it in my hotrod jeep, but I am new to bikes.

I have a 98 ktm 250 exc.

I try and buy the highest octane I can for my gas can, however, I thought about 100LL.

Any thoughts???

Thanks

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I've been running 100LL in my 2-strokes for years. It's excellent fuel.

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let me ask you, do you mix your fuel oil rich because your using 100LL?

I mean I mix a little rich anyway, but I was just thinking the higher octane hotter fuel would benefit from oil rich.

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100LL works great just jet for it. Example on a stock 04 cr250 175 main pump, 182 main 100LL. You have to richen needle and pilot too.:thumbsup:

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so I need to change out the main pump and richen the needle and pilot valves?

did you do that CamP?

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so I need to change out the main pump and richen the needle and pilot valves?

did you do that CamP?

I run Pro Circuit's recommended jetting in both my current bikes. I'm leaner on the main, pilot and needle with my CR250, and leaner on the main on with RM250. It really just depends on the bike, but my experience is 100LL runs slightly richer than the ethanol oxygenated pump gas we have in Texas.

I would recommend that you start with PC's recommended jetting for your bike, and work from there.

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can you help me find the recommended jetting from that link, could you look it up and post the link..

I have a liquid cooled 98 ktm 250 exc, all stock

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Why do you want to run high octane on a stock bike? It makes no sense.

These threads are nearly as common as oil threads. Why doesmn't anyone use the search function??? See the very bottom of the poage.

Edited by William1

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you should use the LOWEST possible octane available to you instead of the highest. not so low that it will cause pinging though. during the 80s mazda was actually running 83 through their race cars. all you're doing by running excessively high octanes is decreasing performance (because you probably didn't jet for it and your motor probably doesn't make the compression) and spending more money.

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One benifit to 100LL is that it will be more consistent than pump gas. But higher octane shouldn't be needed on an unmodified bike.

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from what I read on that link, I came to the conclusion. that a mix of pump and 100LL is best to get the light a heavy molecules. I just need the pump for the heavy, so I guess I can use 87-89 (cheapest) Non ethanol pump fuel, and mix 50/50 with 100LL for the light.

and the 100LL will puck up the slack of the lower octane 87-89

thoughts?

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my next questions would be about premix oil +fuel. Do I mix it oil rich?

Just maintain your current ratio.

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from what I read on that link, I came to the conclusion. that a mix of pump and 100LL is best to get the light a heavy molecules. I just need the pump for the heavy, so I guess I can use 87-89 (cheapest) Non ethanol pump fuel, and mix 50/50 with 100LL for the light.

and the 100LL will puck up the slack of the lower octane 87-89

thoughts?

We can't get ethanol free pump gas here so I run straight 100LL in my 2-strokes. You won't notice any difference in throttle response or power running it straight vs. mixed 50:50 with pump gas.

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We mix it to dilute the ethanol content in regular gas. Not sure if it is helping with that but works great otherwise..

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If you are going to run your motor hard, never go higher than 32 to 1. 18 to 1 will give you the most power. As far as Av gas you can run lean jetting and get away with it(high octane). If you are wanting to get the most out of AV gas, you will have to richen up the jetting. 4 strokes will lean pop out the pipe just with the switch to AV gas. Now if a bike is rich to start with and one switches to AV, you may think it is the best mod you ever done.

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4 strokes will lean pop out the pipe just with the switch to AV gas. Now if a bike is rich to start with and one switches to AV, you may think it is the best mod you ever done.

Our ethanol pump gas runs slightly leaner than 100LL. I occasionally run 100LL in my '08 CRF450. It has stock jetting and runs well, with no lean popping. If you are jetted for ethanol pump gas, your jetting will be in the ballpark with 100LL and you may actually need to go slightly leaner. On the other hand, you my need to go richer if you are jetted for non-ethanol pump gas. It just depends on the type of pump gas available in your locale.

Besides the safety factor that the lead provides, the best thing about 100LL is that it is consistent, whereas pump gas blends change with the seasons and the gas stations.

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