Terrible gas mileage.....

[headwork]

Hey all, just wondering if anyone had any ideas on this issue.....

I only get around 20 - 25 miles to the gallon. I know that I need to get a tune done, the only issue is that the bike seems to run well, all except for a slight miss when idling around 800 rpm. Any thoughts, comments??? The bike is a 93 with roughly 18,000 miles. Stage 7 jet kit with Supertrapps, open tips with 8 or so discs installed.

On the tuning issue...does anyone know a good tuner in the Milwaukee, Wisconsin area???

Thanks,
Josh

 

[maleko89]

What jets are you running? What are your needles set at?

Mark
#1098

 

[4gasem]

I'd go to Dynojet's site and see if they list anyone in your area... I'm sure they do. Call them and see if they will work on the max...

800 rpm? Seems a bit low... Maybe it's a stage 7 thing but if I get below 900 I start having issues...:confused2:

 

[shawn kloker]

Hey all, just wondering if anyone had any ideas on this issue.....

I only get around 20 - 25 miles to the gallon. I know that I need to get a tune done, the only issue is that the bike seems to run well, all except for a slight miss when idling around 800 rpm. Any thoughts, comments??? The bike is a 93 with roughly 18,000 miles. Stage 7 jet kit with Supertrapps, open tips with 8 or so discs installed.

On the tuning issue...does anyone know a good tuner in the Milwaukee, Wisconsin area???

Thanks,
Josh

Set the idle back up to 1100 or so.1000 minimum.

 

[davesax36]

Dead thread revival award coming my way here.....

I've got a similar issue. I know I'm running on three cylinders, but I just put 3.2 gallons in my bike after going 60 miles. I'm pretty sure that's not right. I'm running venture carbs with v-max stock jets assembled by Danny. They were tested on his bike before I put them on mine. He liked them. I thought they were gonna be great since everything started and ran fine. Needs choke to start, so I'm thinking it's not running rich, but then I get super low mileage? I don't even know what else to look at. My fuel pump doesn't run every time at startup. Maybe one click if it's been sitting less than a few hours. I don't see black smoke or smell gas.

Color me frustrated.

 

[gamorg02]

gas is getting 'dumped' somewhere, in my mind. whats going on with the third cylinder? are your float bowls leaking? your gas tank?

 

[dannymax]

gas is getting 'dumped' somewhere, in my mind. whats going on with the third cylinder? are your float bowls leaking? your gas tank?

Carbs just rebuilt, bench checked and installed on my bike for testing....I don't believe the bad mileage is carb related.

As for leaks....Dave said the fuel pump doesn't click after sitting, or maybe one click.

Could out of spec valves cause this? :confused2:

Garrett, think the #3 issue was due to a bad coil.

 

[davesax36]

I'm with Danny, of course, since he just ran these right before I did. There are no fluids on the garage floor. Nothing seems to be coming out of the vent tubes. Cylinder 1 has no spark, but I'm gonna get a coil from Sean. Sync can't be that bad because everything runs pretty smoothly (even though I'm missing one). I'm doing an oil change and clutch replacement Thursday night, so I might have a chance to put a few test miles in. The non-firing plug smells like gas, but is not soaked when I pull it. Other plugs look decent to me. Certainly not 20mpg rich.


This is super confusing/frustrating.



Sent from my Galaxy Nexus using Tapatalk 2

 

[dannymax]

Dave, I think you need to get it running on all four before paying much attention to mileage. #1 cylinder is still taking gas, it's just going out the pipe, and the other three are trying to compensate.

 

[ZackDaniels]

Agreed. If the engine isn't running right there's no point in getting concerned over mpgs. Once that's corrected you can see if it's even still a problem and if it is the list of things to check will hopefully get a bit more obvious.

 

[gamorg02]

i agree with zack and danny. i wouldn't run it too much with one cylinder down, could be 'fuel washing" the cylinder (is that what its called?)

 

[sdt354]

Compression in that cylinder? Always a good starting point for me. Also, the cheapo spark
checkers from HF are invaluable in diagnosing engine issues.
Steve-o