Bonneville America Forums Forums Technical Forums General Tech Vapor lock?

First, thanks to BA.com for info that kept me from getting stranded. I have an '05 BA that I just rode for the first time last week. It died on me after 1.9 miles. I thought it was due to a low fuel situation but because the bike is 4 years old and only has 300 miles on it I pulled off the carbs and sprayed them with cleaner. While I was in there I removed the stock hidden fuel filter and put in an in line. I also removed the AI. I went for a 20 mile ride yesterday and it seemed fine. I went out for a ride today and made it to the end of my street before it died. I remembered reading here about a vapor lock type situation so I opened the gas cap and it started right up. So I took a 35 mile ride and it died on me again after 30 miles. I opened the cap while rolling down the road and it fired right up. I came home and left the bike parked outside in the sun for an hour and it would not start until I loosened the gas cap. I checked the vent hose and it seems ok. Is that little valve on the vent hose known to cause problems? Is it even necessary to keep it? I know I can get a vented cap but it seems odd that this happens every time out.
don

I may be off here but you might have a bad roll over valve.
Heres a link to a Bike Bandit diagram... Look for #20

I figure if its bad and closing up on you it maye be causing a vapor lock situation. Try bypassing it for a couple days...just dont drop your bike.

Thanks,
That is the valve I was wondering about. I'll try running without it and see what happens.
don

No, it's not "vapor lock". Gravity feed, there is no fuel pump so vapor lock can't happen.

It's either a pinched or plugged tank vent line. Take the tank off, look to see if the line is pinched at the front mounting area, it happens very easily when reinstalling the tank.
Yes the valve can stick or get sh!t in it and get plugged up. Easy enough to clean.

big bill is giving the better advice here.
Check that hose for a pinch first.
If no pinch then bypass that valve.

I remember reading on another forum about bad tip over valves. I dont remember if it was effecting our bikes or not. There may be a service bulletin for it or your dealer may be willing to replce it under warranty.


BTW....how did you score an 05 w only 300 miles on it?

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You'd think I'd know what vapor lock means, I owned enough old Fords

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The valve is just a check valve, try blowing in each end. it should be open one way, that would be from the tank to outside.
It's really just a D.O.T. requirement for U.S sales.

Best way to clean that valve is to take it off and throw it in the garbage and just put the 2 ends of hose together with a piece of tubing or vacuum hose coupling.

I checked the line before I posted. The valve concerned me because I am not familiar with it.It's fairly obvious what it is and I can see where it could be a problem. I won't get a chance to ride without it for a while now, it looks like our weather is taking a turn back to winter. This valve is odd to me since there is no mention of it in my Haynes manual. I've never had one before on an overflow/vent tube. The '05 with 300 miles was the result of a guy with a disabling disease who did not want to give up riding. I bought this bike because of my own physical problems, I can't handle a tourer any more. I hope these little glitches work themselves out quickly. Thanks for the reply.
don

It's really just a D.O.T. requirement for U.S sales.
I was hoping someone would say that. I don't feel like buying another one. I did blow in it and it seems a little sluggish. When I get a nice day I'll try a ride without it. Thanks don

It is just a simple check valve you don't need it. It only comes into play if you dump the bike and even then it really wouldn't do much if you have a vented cap and even with the stock cap not sure it would do much. You can also check the vent hose under the bike to make sure a mud wasp didn't nest in the vent tube or a piece of dirt blocking it or something. Try just pulling the valve out of the line and take it for a ride. If the bike runs good then you know either the valve isn't working or there is a blockage after the valve.

It is just a simple check valve you don't need it

That was my assumption. It's just an overflow pipe..I did pull the hose all the way out and check it. I'd like to get a vented cap. I'm trying to find the best deal on one. Does anyone know if the stock cap can be drilled and vented? Thanks.
don

Any vented HD cap that fits 83 and later XL, FXR, Dyna, Softail, or Roadking but it has to be a RH thread cap as some are not. Also be sure it fits right with your dash. The one Brent sells is Kurykakyn part # 8309 and can be purchased at most any place you can get after market bike parts.

Just for info, I threw away that rollover valve and picked up a vented gas cap from the local HD dealer and took a short ( 45 mile ) spin today with no problems. Thanks to all.
don