Triumphrat

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Been a cold winter here in STL, but have been able to fire up the TBird every now and then just to keep the internals in working order. I've taken her out to ride twice in the past two weeks and I've noticed a BIG decline in my gas mileage.

I used to be able to get to about 120 miles before I'd have to hit the reserve, but these past two rides, I've had to hit the reserve at about 75 miles.

I am pushing the bike harder with RPM's running about 4500-5000 as opposed to the 3000-3500 that I was running her at. Would that make this big a difference?

I also have been letting her run while on the rear stand occassionally, just to keep the inner workings going through the winter...would that eat ALOT of gas?

My other thought is maybe the tach. is off, but I don't know.

Anyway, it was GREAT to get out and ride, but this mileage problem (and $3.00 gas) has me somewhat stumped.

Any ideas???

TIA

NoDice

Well, you're getting about 63% of your normal mileage... and considering you're running it at idle (not a bad idea) and also riding a little harder than normal, it **could** amount to that much of a decrease.

Once your full-time riding season picks up, I would run some fuel system cleaner through a tank of good, fresh gas and re-evaluate after the next tank.

If it runs well otherwise, it's most likely not something catastrophic.

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-Chris

MickMaguire

obviously check for leaks... but then I might pull the petcock and check for crap in the tank blocking the inlet screen. Does it take as much as it used to to fill her up?

Failing those its possible that you have a sticky float valve etc in the carb and are over gassing

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Mick...

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No leaks that I can find or smell, so I think that I'm OK there.

Interestingly enough, it only took 2 gallons when I filled it after riding on reserve for about 4-5 miles...did seem like very little at the time, but didn't really think about it.

Does the petcock extend up into the tank or is it just flush with the bottom of the tank?
What is the actually capacity of the tank? I thought four gallons, but I don't know. That would indicate that approx. 2 gallons is still sitting in the tank when I have to hit reserve.

Any advice is much appreciated.

Thanks

jimmyj900

Oxygenated 'winter mix' fuel perhaps?

The winter mix crap usually has a higher percentage of volatiles for easy starting and they'll evaporate quite quickly from carbureted bikes with non-sealed fuel system.

The 'oxygenators' are also fairly low-performance fuel (don't confuse that with octane rating -- different animals) and produce much less power per unit consumed. That can encourage you to use a lot more throttle (and fuel) than normal for the same amount of acceleration you get from 'summer' gas.

Jim

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Eyun_G

I'd say a combination of pushing harder, running in the garage on the stand and the choke are probably your culprits. I tend to see about a 5mpg drop in the winter time, but it doesn't get much below the high 40's most of the winter.

+1 on the fuel cleaner, I'd suggest seafoam or Berryman b-12 chemtool. They both tend to work wonders especially on carbon build up from short trips and rich winter running while cold.

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Cooler than the other side of the pillow.....

MickMaguire

If it takes considerably less to fill then its likely the filter screen on the petcock. Yes it does extend up into the tank, or at least the "normal" position has a feed tub that extends up into the tank. This tube has a 1 inch or so long filter on the end of it. Worth pulling to check if its clear. Drain the tank and remove it then lay it on its right side and remove the petcock (this way you wont get gas everywhere) and inspect - the seals are reusuable so generally no worries there. Its a simple job and worth looking at with these bikes as they do get rust and paint in the tank which can block the screens (as can gunk form old fuel).

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Mick...