78 gs 750 low fuel mileage

[therealdunbar]

I've been getting about 20 mph was wondering what the average was, i recently changed out the petcock due to fuel making it into my oil aswell as adjusted the floats to 23 mm from the top of the circular float . also there is a hole in the exhaust and 1+2 headers are hotter then 3+4 any insight would be appreciated

[bbjumper]

Not enough information to help you, is it a stock bike, intake and exhaust? Has all of the regular maintenance been addressed?

[bbjumper]

My G is stock and I regularly get in the mid 40's

[razor02097]

Here is his other thread...

http://www.thegsresources.com/_forum/showthread.php?t=195797

First off how are you measuring fuel economy? Measuring fuel economy on a motorcycle is more difficult to do than a car. You have to fill the tank to the exact same level each time and make sure other variables are taken into account such as if you had to change the front tire to a slightly larger diameter like I had to on my 300.

The pipes should temp about the same. The cold 3 and 4 pipes seem to point to a fueling issue... but could be the plugs or wires going to those cylinders. It could also be the wires might be switched. One coil goes to 1 and 4 the other 2 and 3. I would start by pulling the plugs out and check the level of fouling on all 4 cylinders. If the plugs are old now would be the time to start with a fresh set. A set of spark plugs can tell you a lot of things about the running condition of an engine.

[tom203]

You still got a vacuum petcock? connected to #3 carb? make sure it's not leaking gas down vac line and fouling #3 plug

[therealdunbar]

I believe everything is stock except the exhaust and (4 into 2) I've replaced the air filter, oil filter, spark plugs and petcock. I've checked the points, compression, and synced the carbs sorry for the little amount of info im fairly new

[MisterCinders]

Put your location in your profile. Maybe a GSR member is nearby to help you.

[therealdunbar]

i picked up a new oem petcock recently and will be keeping an eye on the vaccum line, i will also be looking at the wires thank you for the ideas. i have discovered a small amount of fuel coming out of the overflow which leads me to believe i set the float hights incorrectly. im unsure of where to measure on the floats as they are circular, if anyone has any knowledge of these floats i would appreciate it

[1_v8_merc]

I think the manual calls for Float Height to be 25-27mm.
If you're set lower than that, you're running way rich.