Vapor Lock

I have a 2.6 gal. Clarke gas tank, Clarke gas cap with an anodized al. breather cap. Got vapor lock last Sunday racing..............kept stalling. Has anyone experienced this problem?

Vapor lock in motorcycles is extremely rare. It occurs when the fuel in the lines leading to the carb evaporates in the lines at such a high rate that bubbles of vapor are formed and block the flow of fuel.

It's rare because motorcycle fuel lines are very seldom made of metal, and are very seldom exposed to the kind of heat automotive fuel lines are, what with being out in the open and such.

On the other hand, if your tank doesn't vent well enough, it can stop the fuel flow if a strong enough vacuum forms. But you can check for that by letting the open fuel line drain into a gas can and see if the flow is continuous. If it slows, open the cap. If that speeds it up, you have your culprit.

It is rare to hear of vaopr lock in a bike, actually I don't think I've ever heard of the case. Are you sure that's what's happening? Maybe your float is just getting stuck closed, or the filter screen in the fuel tank is clogged up?

Along those lines, I saw in dirt rider that some of the pro teams are running heat reflective tape on the bottom of the gas tank and sides of the carb. Something about boiling the fuel in the tank and carb, and I think it was a Kawasaki team they used for the example but I don't remember for sure.. Not many of us get the bikes as hot as a pro would, but if you really think you're having heat related problems them maybe that would help.

Vapor lock in motorcycles is extremely rare. It occurs when the fuel in the lines leading to the carb evaporates in the lines at such a high rate that bubbles of vapor are formed and block the flow of fuel.

It's rare because motorcycle fuel lines are very seldom made of metal, and are very seldom exposed to the kind of heat automotive fuel lines are, what with being out in the open and such.

On the other hand, if your tank doesn't vent well enough, it can stop the fuel flow if a strong enough vacuum forms. But you can check for that by letting the open fuel line drain into a gas can and see if the flow is continuous. If it slows, open the cap. If that speeds it up, you have your culprit.

This happened to me on my IMS tank there was no hole drilled for the vent. The bike would run for a while then run out of gas and die.:thumbsup:

The same problem happened to my buddy... He had his $20 billet aluminum breather that was full of dirt and would not allow the tank to flow correctly... Go back to the tube and elminate the problem... just my $.02

Yes, I'm sure that was the problem. Another guy at the race rounded his counter sprocket teeth off, quite early. I used his gas cap............ bingo

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now