Hey, Everyone! It's been awhile since I've posted, been busy with other priorities. Now that the sun's out and (good) riding weather has returned, my S40 has reminded me of the little annoyances that I've just learned to live with. You know - the weak midrange, the long warm-ups, the afterfiring on roll-off and shutoff. A friend (HD rider) told me about a little country gas station that now sells non-ethanol unleaded gas exclusively. Well, I tried some and - many of those annoying problems went away (or were less noticeable). The power band seems smoother and stronger also. Anyone else out there have a similar experience? Maybe these bikes just don't like ethanol.

BTW, this little place in Ollala, WA saw about 20 other bikes parked there that day. They also serve beer and pizza. Looks like it's a pleasant biker hang-out.

I read a technical reason why somewhere but I forget what it was. Basically, like Dave said, ethanol will require a richer AFR. Since our engine was designed before ethanol was prevalent, "pure" gas will make it run a bit better.

Art Webb wrote on 05/11/15 at 10:41:05:


Technically it's BTU's, not calories...but the concept is correct.

It's like tuning a two-stroke bike with premix. The lower the fuelil ratio, the leaner the mixture. I can't tell you how many people have told me that they run 32:1 and need to rejet to get a little lean, and I've told then to try going to 28:1 or 24:1 as it's the same thing.