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jetting/mileage/backfire q

Old 03-28-2008, 07:22 AM
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jetting/mileage/backfire q

I posted a few weeks ago about backfires thru the carbs just off idle. I know I need to re-jet to fix the problem and maybe do a sync, but my question is this...my sh only gets about 90 miles to a tank before light is flashing and it takes 3 gallons to fill back up, so that is 30 mpg but is not corrected for speedo inaccuracy, so I figure about 27ish. How much more will i loose with correct jet and mixture settings? I have sock gearing(I think). Vortex 43 tooth rear and I assume the 16t front still.
I have actually re-jetted a car carb and seen better mileage even though I fattened it up, but I just don't see it happening in this case.

The only mods so far are Jardines.
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Old 03-28-2008, 09:33 AM
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All stock I get ~35ish depending on how I ride. If I really wring the throttle I can get as little as 90 miles on a tank, if I am light on the throttle I can get as much as 145 miles.. I usually get 120ish / tank.
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Old 03-29-2008, 03:43 AM
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Better A/F ratio will provide a more efficient burn, lean mix burn waaay slower and some flame dwell in the cylinder while most of it is exhausted (wasted energy), when the fresh mix meet the remaining flames it burns and pop trough the open intake, then compress the already burnt and slightly pressurized charge and kick back even more.

Spot on mixture yield better power stroke, better mileage, happy rider, happy accountant
There is no way to turn the superhawk in a fuel efficient machine, we will need to, add flywheel weight, rise compression, regrind the cams with less duration, fill the large ports, set as much advance as possible, EFI and maybe cut a cylinder with a hacksaw
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Old 03-29-2008, 06:51 AM
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I've had mine rejetted and all that trash, and I'm only getting about 29 on an average, around-town kinda day. If I'm in the twisties, it sinks to about 27, and mostly highway gets me 32ish. YMMV, however, I doubt by much.
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Old 03-29-2008, 10:05 PM
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i get about 30 mpg also i have the jardine high mounts also. the original owner rejetted but i may want to have it redone seems lean.
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Old 03-30-2008, 03:27 AM
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I have 15/41 gearing and that made a big difference I think. I used to look for a gas station around 90, now it's more like 80. Even then it's only taking 2.5 gallons, so I could go a lot further.
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