Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board Breather on B25 fiberglass oil tank

I have a B25 fiberglass oil tank that's missing the breather. All I have is the threaded stub the breather screws on to. The parts book doesn't show the breather as a separate piece. Does anyone know what the thread is on the that "stub" or in the alternate where I could get the part I'm describing?

Ken
Eastern Ontario

There are flats (like a nut) on the breather but I've never tried to unscrew one. I'd like to see what that looks like. Is the threaded stub hollow?

You gotta photo?

I’ve probably have an oil tank around here that I could rob the breather off of……I just didn’t know they could be removed. I’ll give it a try this weekend.

Alright……any of you know if that breather just screws off????

Fiberglass BSA B25/44 oil tank.

The breather definitely screws off. I know that because my breather is missing.. There's a fine- threaded stub that sticks up the breather screws on to. In the parts diagram it shows the breather on the oil tank with what looks like a thin locking nut under it. Presumably the arrangement is so the breather can be directed in whatever direction you want. I've got a later steel oil tank that has the same breather but it is definitely not screwed on. It's likely been brazed in position.

Ken
Eastern Ontario

Gotcha........I misread your first post and turned "stub" into "stud" in my head. Sorry.

You sir are 100% correct.......it screws off. Something I didn't know before your post and I thank you for bringing it up. Odd that there doesn't seem to be a part number for it. Looks to be part of the tank in the parts book. Those flats should have been a dead giveaway. BUT it took some force to get it started.....looks like they used a thread sealer?



I love the sculpted look of the fiberglass......but I've learned to like the metal fuel tanks, especially with our fuel. But both of my Roadsters and my C-25 still have the fiberglass oil tanks.

Have no clue what the text on the bottom of the tanks means........but all my Fiberglass tanks carry these type of birthmarks. Always pretty crude.

Ken......IF that one looks like it'll work for you......I'd be happy to send it to you? I'll PM you.

Thanks very much for your exceptional offer. I'll PM you. Before using the fibreglass tank I had a look in Rupert Ratio's book on BSA singles. He seemed equally happy with either the steel or fibreglass tanks. In the case of the gas tank, definitely steel.

Ken,
Eastern Ontario

The only problem I’ve had with the fiberglass oil tank is I had one (1) fail at that lower solid peg ( for lack of a better term). Leaked around the peg. Used a dremel to create a space around the base of the peg and filled it with epoxy. Several hundred miles later and at least a couple of years and it’s been leak free.

I tried and had someone else try sealing my fiberglass fuel tanks…..but all attempts eventually failed.

Steel or alloy is the answer……if you’re going to actually ride the bike.

No idea if its true but the workers are said to have made the fibreglass tanks at home and the marks are made by them. They were given the moulds and laid the resin and fibre up in the mould after work. Making the tank did not take long but the curing time was considerably longer so it freed up space at the factory.

I was a bit concerned about the fibreglass tank but given the amount of sludge I took out of mine it had been in use for some time. Rupert Ratio mentions them in his book about BSA unit singles. He seems to think they're quite acceptable, at least based on his remarks. Certainly the fibreglass is a lot thicker than the fibreglass side panels.

Ken
Eastern Ontario