You are here:

Motorcycle Repair/Fuel Starvation


Hi I have a Virago VX750 1992. It runs lovely until it grts to 4500-5000 RPM then its just as though it is running out of petrol. If I operate the choke it then runs OK iT SEEMS TO DO IT IN ALL GEARS. hAVE STRIPPED AND CLEANED CARBS BUT MADE NO DIFFERENCE hELP pLEASE

Peter, I am not very familiar with Yamaha products specifically, but a quick look at some online microfiches shows that the petcock/fuel valve has screens up inside the fuel tank, which may be plugged up from rust/debris or just aging components.

The things that slow fuel flow are the petcock filters and perhaps if the gas cap or venting system for the fuel tank is causing a partial vacuum at higher fuel demand situations.

If your petcock looks like this:

There is also a vacuum diaphragm line on the back side. If the diaphragm fails, you get an air leak and loss of fuel delivery.

Bill Silver

Motorcycle Repair

All Answers

Answers by Expert:

Ask Experts


Bill Silver


Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.


I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

VJMC (Vintage Japanese Motorcycle Club) of North America

VJMC newsletter, as editor for two years and as contributing editor currently.

3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

©2017 All rights reserved.