Yank the "high tech" vent line off, and replace the WHOLE thing with a boring, plain old vent line. Route the vent line using the OEM method.

If your problems still exist, you have just alleviated one of the "possibilities" and you can continue on with your troubleshooting.

[This message has been edited by Kevin in New Hampshire (edited 05-18-2000).]

Originally posted by Scott:

OK, here's the situation...

I was riding yesterday in the woods of Colorado. (Rampart, for you CO guys)

After about an hour of riding, my WR started really bogging. I was cruising the trails when all of a sudden the bike started acting like it was out of gas - chugging violently. I would pull in the clutch and feather it to keep the bike running. It seemed to happen the harder I hit the gas. If I stayed on the gas the bike would die.

One thing I noticed was that there was a ton of pressure coming out of the gas cap exhaust tube. I loosened the gas cap and there was some serious pressure goin on.

Any ideas? Jetting? Blocked fuel line?

I would think that if it was jetting, the bike would be doing this all day, not just after an hour or so into the ride....


That hissing niose can be either air trying to get in or out.

i think it's trying to get in, not out! your tank breather was possibly kinked causing a vacuum. the only place the tank can get air is from the float chamber on some bikes. that's why you get a lot of bubbling in the fuel lines (on some bikes!).

I haven't pulled my WR around much yet but i know that Fuel filters "melt" when you muck about with additives, boosters & hot fuels causing a lean mixture. I suggest scott that you try a long piece of pipe that goes around your bar support loosely four times before disappearing down your er "triple clamps". Taffy.

[This message has been edited by Bryan (edited 05-19-2000).]

Hey Guys,you are not alone! I experienced the same symptoms twice before. The first time I replaced the one way valve thinking it was causing the problem. This was a waste of time since the next week it happend again! I have a 98 wr with IMS tank and yz seat,with stock pipe, and the temps were in the 60's, not too hot. It turned out that the new place I bought gas from both times was the reason. For some reason their gas had a tremendous amount of vapor pressure. Within minutes my 5 gallon gas can was bulging and needed the vent to be left open. Before you make any drastic changes to your bike, try a new source for your fuel!

Thanks you guys, I have a brand new 426 that has been dumping fuel through the carb vent hose out of the float bowl ever since i brought it home - everyone was telling me the float was stuck so i took the carb apart 3 times now looking for debris or hangups but found nothing, and then the bike would run fine for a couple hours and then start dumping fuel again. I have noticed the extreme pressure build-up in my tank and i am now quite certain that "kevin in new hampshire" has solved my problem. If there was that much pressure in your tank the only way for it to escape would be through the carb, right? At least i hope that is the answer to my problems, too bad i work out of town and won't get to experiment until next weekend (plan to be drunk at high point this weekend!)

All this talk takes me back to a problem I noticed when I installed the IMS YZ tank. I had to reverse the fuelcock and run the gas line behind the engine, between the carb.

I was using a clear fuel line and I noticed the fuel was not flowing smoothly. There were many air pockets in the line. Unless the bike was in motion, the fuel would not flow.

I tried everthing to fix it. Re-routing the line. New vent hose on cap. Using the stock cap and hose. Nothing worked.

Then it hit me. It was so easy. I bought a black rubber fuel line. :)

WOW - I just got back in town and checked the forum! Thanks for all the responses!

I will try to eliminate the one way breather thingy tonight when I get home... I'm hoping I can simply unscrew this "piece" from the gas cap.?

Hope this works!

(I thought of the bad gas possibility, but discounted it because I thought the bike would act up sooner... but maybe not.)


99WR,WR timing,throttle stop removed,Twin Air filter,E-Series,carbon air box,Pro Tapers,front and rear lights removed

I removed my check valve today. The hose was still long enough to use the normal routing path.

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