Gasoline smell

[wild bill]

well,all thru winter havn't started the bike which resulted in me rebuiding/cleaning curbs.What a job!
Anyway,the bike runs like a scalded monkey,the only prob is the gas smell when parked in garage.
I don't see ant check valve that would keep the tank under pressure from evaporating fuel,and a t the same time allow fresh air in while running to avoid vacuum in tank.
Any ideas?

Thanks.

[Michvalk]

There are no check valves of any kind. Gas smell can come from the gas cap. Some don't seal like there supposed to. Some have added a thin gasket to the cap and it has helped. I assume you have checked to make sure there are no leaks in the fuel lines. Doesn't take much to smell strong

[Pete]

Treat the gasket on the fill cap with a high quality silicone, let it soak until it will not absorb any more silicone. Also check the sealing surface for any irregularities on the tank and seal, clean and repair.

This trick has worked for me quite well on older bikes, of course you could replace the gasket but I would soak the new gasket before installing it.

[wild bill]

thanks guys,will do.
It's interesting to me,sine I don't believe in coincidences  that it happened after bike has been dormant for 6 mos..
Also,let's say the gas cap seals well-where does the air enter the tank when the fuel level drops? Thru the vent pipe on the bottom of the tank connected to the hose.Some had problems pinching this hose and bike stalling.So,what makes the air to enter the tank thru it ,but not exiting in the form of fumes?

[John U.]

thanks guys,will do.
It's interesting to me,sine I don't believe in coincidences   that it happened after bike has been dormant for 6 mos..
Also,let's say the gas cap seals well-where does the air enter the tank when the fuel level drops? Thru the vent pipe on the bottom of the tank connected to the hose.Some had problems pinching this hose and bike stalling.So,what makes the air to enter the tank thru it ,but not exiting in the form of fumes?

I haven't heard this mentioned before but as far as I know there is nothing that prevents a small amount of gas fumes from exiting the tank through the vent line. Gas fumes are heavier than air so in theory they would fall from the vent line to be replaced by air. The vent line is thin so the amount of vapor exchange would be small but measurable. Temperature changes would have an effect on the amount of venting also.

On another train of thought, if the fuel lines were dry for an extended period during carb cleaning the O-rings will dry out and leak until they swell up. Eventually they need replacement, I'm planning to replace my lines and O-rings this winter.

[Pete]

thanks guys,will do.
It's interesting to me,sine I don't believe in coincidences  that it happened after bike has been dormant for 6 mos..
Also,let's say the gas cap seals well-where does the air enter the tank when the fuel level drops? Thru the vent pipe on the bottom of the tank connected to the hose.Some had problems pinching this hose and bike stalling.So,what makes the air to enter the tank thru it ,but not exiting in the form of fumes?

There is more to the vent pipe that one might think. On the upper end it is baffled to prevent liquid from entering under normal conditions. On CA bikes the vent is more complicated with a fume retainer toward the end of the vent line.

Normally you would never smell fuel vapors from the vent line. Unless you overfill the tank and the fuel gets hot and expands, then it goes either out the vent or the cap.