Bonneville America Forums Forums Technical Forums Performance Mods fuel consumtion

hi i have rejetted to 155 mains 45 pilots tbs needle pod filters, stock exhaust drilleed i baffle loads of holes, 16 tooth sprocket bikes lowered , it goes great quick on take off and revs to 7500rpm only trouble is now i am getting 38 to 40 miles before it goes on reserve im guessing the reserve is a gallon so im getting 20 mpg ? is this normal im sure it used to do a lot more plugs are slightly dark but not soot black any answers kevin

20 mpg? That's probably less than half of the average around here. No offense intended - but check your math again! Otherwise something is really wrong.

take out the 45 pilots, try 42's no need to go up unless you get excessive popping. did you have a flat spot that caused you to go with the tbs needles? if you can get it on a dyno and find out that a/f

Frank

Main tank is 3.4 USgal.

If your math is right you're getting 12mpg.

I have a heavy hand, and get 25-33mpg, one of the lowest here.

Either your math is wrong or somebody's siphoning your tank.

Folks don't usually make those kind of changes unless they change their pipes too. Were those jet changes recommended by the makers of the pods? According to Dinqua's Jet Calculator (http://www.dinqua.com) you should be running 148,5 mains with your configuration.

Those jets do sound big for just 1 baffle drilled but I don't think thats your problem if your mileage is that bad. Those are the jets I run with 48 pilots and I get better mileage than that. I have totally gutted pipes with just the reducer cone left in with pod filters.

Sounds like you need to match your inflow to your outgo. Pipes.

Either that or you've got a fuel leak somewhere.

The TBS needles and the still baffled stock pipes will do that. Get some free flowing pipes and go back to the stock needle.

I average about 120 miles before reserve (~35 mpg) on a very similar setup (freak, 45/TBS/155), save that I have Bubs.

yeah, I agree with going to a smaller main jet and stock needle with 1 shim. my 2 cents

hi thanks for replies i put down the exhaust stats wrong i have drilled out all the baffles in the stock pipes and only left 1 this i drilled with six holes so it is free flowing , i think i might change the pilots back to 42 other than that it run perfect i have just put in 15 pound ,worth of juice full tank and going o ride it till it runs out and do the maths from there

The jets you currently have sound pretty close to what you should have. I doubt you need to go to a smaller pilot, maybe a 150 main but you should be close with the set up you already have.

pics of me bike on facebook search -kevin tba james and you will see a very fast tba

One formula for a fairly consistent 50 MPG US with 10% alcohol (methanol?) fuel for an 865

Stock pipes with two of four baffles removed. Remaining two baffles have four each of 1/4" holes drilled in them.
They're a little loud, but you can't say it doesn't sound like a Triumph.

132 jets

Drilled slides

Uni filter

Stock needles with no shims

Stock pilots


A dyno run indicated the above offers optimum air to fuel efficiency, with pretty close to stock HP & torque. I may have gained a horse or a pound or two, but I don't recall. It's all good.

The above is definitely not the path to maximum potential HP, but it does breath well this way, and at almost $4 per gallon for gas, it keeps me happy. (I am a cheap bas*** though.) I tend to try to ride for vehicle longevity most of the time, so I don't seem to miss the HP large jets would bring my way. I'm happy enough being in the wind, and hearing the Trumpet music. {By cracky!}

Don't forget the Suzuki oil...

hi all just did 70 miles before she spluttered onto reseve , so the new pods have given me better fuel consumption , one of the old pods was split halfway round and this was probably upsetting the mixture , when i had the tank painted my petcock was clogged up so i swapped with a differnet petcock of of a tbird i think anyway the reseve line was slightly higher than stock and the dealer said the only difference is that i will get more on reserve,so i think normally its half a gallon (uk) in reserve and i probably have 3/4 gallon, so i am getting for 2 and 3/4 gallons 70 miles, works out 25/6 miles per gallon , it revs a bit higher in top gear than normal 17 tooth sprocket bikes so take this into consideration i think its roughly ok do you? i am going on a long run to germany soon might put the 18 tooth on what do you think thanks kevin