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I did a write up on my original mods, and I also did a write up on my air cleaner mod. They are out there somewhere...This last tweak was something I've been thinking about for a while. I had marbled the AIR system several years ago, and sealed off the air switching valve's intake port, but there was always something that bothered me about just doing that. My fuel mileage had gone from high 30's/low 40's with those mods, and I had gotten as much as 52 a few times at higher altitudes. When Greenbarn and I rode to Drift-In last year, we got almost exactly the same mileage, 45+....Sooooooooooo, here's what I did this last time around. You really need to understand, up front how things like air temp and altitude effect this kind of system. The fuel map is the map....this throttle opening, this rpm, this engine temp, and you get this fuel delivery....BUT that would give no possibility of modifying for engine load or for altitude. The MAP sensor is connected to the intake manifold, and is a vacuum gauge. It tells the computer that at this throttle opening, the bike is either coasting, or climbing a hill. Coasting will cause higher manifold vacuum, so the fuel will be leaned out...hill climbing has exactly the opposite effect. Higher altitudes require less fuel, since there is less oxygen...so we have a BARO sensor...and then there is a little critter called the fuel pressure regulator. This is a vacuum operated device that adjusts the fuel pressure outside the control of the computer. Normal running pressure is about 30 psi...Heavy loads cause a drop in manifold pressure, so the regulator responds by increasing the fuel pressure, all the way up to full fuel pump output, around 45 psi. A pressure increase like that will play hell with the fuel mileage. I removed the air switching valve completely, and plugged the hoses to the reed valves. I sealed off the vacuum line to the valve, which just so happens to also control the fuel pressure regulator and the MAP sensor....I ran 193 miles on one tank of fuel...today!

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Topic summary

Posted by 49Reo

- July 05, 2015, 11:10:39 AM

So... what did you tweak. care to share?

Posted by Troll

- July 04, 2015, 16:50:40 PM

Long story short. I did another little mod to the EFI and rode 100 miles today on a near perfect day. Riding between 60 and 70 mph (when I wasn't in some little town), I got 50 mpg, here at sea level...BIG SMILE...Ran BEAUTIFULLY! Never better!..Stopped here for a quick lunch

Posted by greenbarn

- June 15, 2015, 20:41:07 PM

Quote from: 49Reo on June 14, 2015, 20:56:51 PM
...the car that came with a sniffle...

I'm afraid that one went over my head....

Posted by 49Reo

- June 14, 2015, 20:56:51 PM

...the car that came with a sniffle...

Posted by pcarrell

- June 14, 2015, 18:35:48 PM

Fun toy!

Posted by CDNRatMan

- June 14, 2015, 18:24:21 PM

If that is what I think it is then we have 2 here in town and I know the one lad that owns one of them and he has it in all the car shows.......Marty McFly would be impressed with it......lol...

Posted by Troll

- June 14, 2015, 15:50:51 PM

It was supposed to be raining today, but it didn't. Turned out to be 85° and mostly sunny. I put on about 180 miles going basically nowhere in particular. On the way home, passing through the thriving metropolis of Brackett, WI, I saw this parked by the town's major (and I think, only) employer.

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