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10% Ethanol recipe for a lean mix?

This is a discussion on 10% Ethanol recipe for a lean mix? within the Rebel forums, part of the Honda category; I picked up a new 2009 Rebel 250 a few weeks ago. Very happy with it so far. The weather ...

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Old 04-19-2010   #1
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Default 10% Ethanol recipe for a lean mix?

I picked up a new 2009 Rebel 250 a few weeks ago. Very happy with it so far. The weather was very cool the day I picked it up and the salesman remarked that if I plan to ride in weather this cold a richer jet may be necessary.
On the highway, in cold weather I got about 75 miles per hour but little more. On a warmer day I was keeping up with traffic above 80 miles per hour.
Here in Maine our fuel contains 10% ethanol, based on what I've read and some crude math I think the correct air to fuel ratio for this fuel to be 14.4 to 1. I am wondering if a jet change might improve the top end performance. Input, suggestions or criticism appreciated.

June 1, 2010.

After doing a bit of research and a little math I elected to change the main jet to a 115. I've noted a slight increase in top speed, but it still seems to be a function of temperature. I just got back from a short trip ( about 20 miles ), and on the way home the road was warm , temperature about 80F on highway, and with a warm engine I was getting a solid 85 mph.

Last edited by referelectrician; 05-31-2010 at 01:18 PM. Reason: share results of experiment
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Old 06-26-2010   #2
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When you are riding through cold air, the air is much more dense at 30 DEG than it is at 80DEG, and without an aerodynamic windshield, you yourself are a very good wind catcher! And, with EPA smog jetting, the warmer the intake air, the more power it will make. other that drilling 2-3 half inch holes all the way through the baffles (both walls on each pipe) and changing the intake system to assure cold air intake, with the proper jet for your altitude and freer breathing engine, there is nothing more that you can do, but doing what I said, will see a 10-15% power increase.
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