Gas Cap Seal

Does the VF700/750 gas cap completely seal or is it open for venting purposes?

 

My '83 750 manual says to "Check the vent hole for blockage." So there is a vent hole there somewhere.

 

Fuel would not make it out of the tank if it wasn't vented, and with FI the pumps are strong enough to collapse the tank without venting......no experience with the earlier years, but the later years had tanks with internal vent tubes, with hoses that exit out the bottom of the tank.....not sure if that helps, but it does make me realize I need another beer....

 

Had a new Bonneville with a blob of weld clogging vent tube, poor oener broke down twice before i could take it out on an adequate ride to experience it myself. When i cracked the cap, i got a "whooosh" when i stuck a piece of safety wire in the tube it was blocked. A new petrol tank solved the problem. Cheeers

 

Could anyone check their tank? Takes a minute.
-Open cap
-Wipe the sealing surfaces
-Use a highlighter to color tank surface
-Seal/lock cap and open back up to inspect the ring on cap seal. Any spot that doesn't have highlight residue isn't sealing.

 

What is it you are trying to achieve, the cap is designed to prevent fuel splashing out but not to make a perfect seal, if you tip the tank upside down fuel will leak out

 

Tank venting is either thru a breather in the cap (thru the key slot) on a 49 state model, or thru a separate vent that goes into the smog system on CA models. I have had to blow the cap vent out before to cure a fuel delivery problem.

Most of my tanks will leak fuel out of the cap seal to some degree in certain situations. A full-ish tank lifted vertically by the rear mount hole will certainly leak around the cap, usually that is just too much pressure to hold back completely (as stated above). Most of my bikes are fine with a full tank sloshing around while riding, but I have a couple where the cap is old with a lot of miles on it, and they sometimes they will leak slightly during normal riding after being filled up. I usually don't completely fill my tanks just for this reason.

Perhaps some sort of product or concoction for rejuvenating rubber could help a seal that is old, hard and compressed to the shape of the tank sealing lip.

 

Nice, I had to pop for a brand new cap for my 93 as the old tank was filled with rust and the cap was crap. Now i have two different keys, which is not a total hardship, would be nice to have one though. I always top off my tanks into the filler neck, this was major problem ehen i had a CA bike and it fuked the charcoal canister :frusty: what a pile that bike was! Anyway, cheers

 

You can have keys cut with both numbers, one on each side. Had it done for customers all the time.

 

Tested both tanks [good and bad] both don't seal all the way, so I guess that's how they came. Was hoping to line the tanks but can't get the black rust within the gas cap bevel on the inside of the tank. The cleaning of what rust I could will be all I can do.