February 10, 20224 yr During the last few rides on my 2016 Beta 300 4t, I started smelling fuel. I have a clear tank vent line and I can actually see gas bubbling up the line. A 1/4" or so of air will be followed by a 1/4" of fuel and so on. It sort of slowly oozes out the top of the vent line. A long time ago I put on a long vent line because fuel will spill when pointing sharply down hill and ran this a long time before this issue. See picture. The fuel line is not too near the exhaust. The bike is not overheating and the tank did not feel particularly warm when I put my hand on it. The tank does not have to be full for it to happen. It does it with and without the vent fitting on the end and with the tube facing up and the tube facing down. The hot start line was touching or just about touching the exhaust. I have corrected but not tested and don't see how that could create this issue anyway. The bike runs well but can somethings be finicky to start. Are there any ideas on this? Edited February 11, 20224 yr by mcman56 correct spelling
February 11, 20224 yr EVO filler caps / vents do not have a good reputation. Invest in a CSP one . Job done.
February 11, 20224 yr Author Are you saying fuel normally comes up out the tube? I can be sitting on the bike not moving and watch it bubbling. What would push the fuel up? For something to flow out it, there would have to be expansion or some kind of flow in. I looked up CSP caps and only see them for 2018+. They do not include a vent line. I believe 2018+ has a vent line connected to the tank directly. Mine is a 2016 and would need a vent.
February 11, 20224 yr I'm pretty sure I've read posts on here about this from someone a few years ago. Sorry I don't remember the outcome but it's worth trying a search. I haven't noticed any bubbling with my Evo.
February 12, 20224 yr Author 9 hours ago, totty79 said: I'm pretty sure I've read posts on here about this from someone a few years ago. Sorry I don't remember the outcome but it's worth trying a search. I haven't noticed any bubbling with my Evo. I found it, thanks. There are two springs and a couple of sealing spots in the cap. If things get out of shape, I wonder if it can sort of become a pump. I cleaned and reassembled and will see what happens.
February 12, 20224 yr my 2018 300 2t has (had) a vent line. CSP cap fitted & vent line removed plugged. Have ridden in quite few events with no issues.
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