kiwiaudio Posted March 14, 2008 Share Posted March 14, 2008 I performed complete surgery late last year and had no problems. In fact, I thought the old girl ran great and was very happy to rid of that canister, and I just love to remove unnecessary s..t you know! First ride yesterday, after a long winter, and pulled into a gas station almost on empty. Huge suction ...pfffffttt... on opening the tank cap, and another later one later on when the tank was full. I checked my vent line by removing the BMWST recommended check valve and blowing through it, and it is clear to the tank. I had fitted the check valve, i assume correctly, to allow vacuum into the tank, so ... ?? I left the check valve off for now, and wont get to ride again until the next break in Ohios weird weather cycle. Any ideas ?? Link to comment
smiller Posted March 14, 2008 Share Posted March 14, 2008 Are you sure what you were hearing was suction? A one-way check valve will let air into the tank but not allow fumes to escape... this can cause a buildup of pressure in the tank that you can sometimes hear escaping when you open the fill. Link to comment
Joe Frickin' Friday Posted March 14, 2008 Share Posted March 14, 2008 Are you sure what you were hearing was suction? A one-way check valve will let air into the tank but not allow fumes to escape... this can cause a buildup of pressure in the tank that you can sometimes hear escaping when you open the fill. Depends which way the checkvalve is installed. If there was pressure in the tank, the lid would have POPPED open as soon as he turned the key. Link to comment
kiwiaudio Posted March 14, 2008 Author Share Posted March 14, 2008 Good point Seth, - Honestly, it may very well have been pressure, instead of vacuum. Now the question I guess is how to differentiate. I'll hold my face right there next time and see if I can tell - I'll get a blast of air or I won't ! If it is indeed pressurizing, that seems like a good reason to chuck the check valve huh ? Link to comment
smiller Posted March 14, 2008 Share Posted March 14, 2008 If it is indeed pressurizing, that seems like a good reason to chuck the check valve huh ? Well, if it's a one-way valve then some pressure in the tank is going to be a necessary byproduct since air will be admitted into the tank but not allowed out. But I haven't ever known it to build up enough to be problematical. You do have to ensure that any went line connections between the tank and valve are secure though or you can get some liquid seepage at any leak points. Link to comment
OoPEZoO Posted March 14, 2008 Share Posted March 14, 2008 If it is indeed pressurizing, that seems like a good reason to chuck the check valve huh ? I'm running mine without a check valve. I just ran the tube down and cut it even with the other tube that is by the right foot peg. I tend to fill my tank right to the top while sitting on the bike upright (I've put in as much as 6.8 gallons), then I ride the .4 miles to my house and park the bike.........I've never had any adverse effects Link to comment
smiller Posted March 14, 2008 Share Posted March 14, 2008 There isn't necessarily any adverse affect from not using a check valve, other than a gas odor if the bike is parked in an enclosed hot garage. We have a few of those in Texas. Link to comment
Boffin Posted March 14, 2008 Share Posted March 14, 2008 If it is indeed pressurizing, that seems like a good reason to chuck the check valve huh ? I'm running mine without a check valve. I just ran the tube down and cut it even with the other tube that is by the right foot peg. I tend to fill my tank right to the top while sitting on the bike upright (I've put in as much as 6.8 gallons), then I ride the .4 miles to my house and park the bike.........I've never had any adverse effects Every non-US market bike is running without a check-valve. Other than gas fumes in hot garages, should be no issue. Andy Link to comment
Huzband Posted March 15, 2008 Share Posted March 15, 2008 If it is indeed pressurizing, that seems like a good reason to chuck the check valve huh ? I'm running mine without a check valve. I just ran the tube down and cut it even with the other tube that is by the right foot peg. I tend to fill my tank right to the top while sitting on the bike upright (I've put in as much as 6.8 gallons), then I ride the .4 miles to my house and park the bike.........I've never had any adverse effects Just don't fill it then park it in the hot sun. DAMHIK. Link to comment
Stan Walker Posted March 15, 2008 Share Posted March 15, 2008 I checked my vent line by removing the BMWST recommended check valve Could you point us at this? I don't recall ever seeing it. Stan Link to comment
kiwiaudio Posted March 15, 2008 Author Share Posted March 15, 2008 Stan, I meant only that I saw it recommended somewhere on this forum. Link to comment
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