Britbike forum Forums Thread Like Summary - MAP oil filter - hose size problem

The oil lines on my BSA are 5/16", but the spigots on the oil filter are 3/8". I can't change to 3/8" hose, because all the fittings on the bike are 5/16". It looks like the fittings on the oil filter are not removable.

I can get the 5/16" hose onto the filter, but it's a "stretch" (literally). It's not pretty but I guess it'll work.

Is there some other solution to this problem that I'm not seeing?

(BTW, the blue is masking tape. The bracket will either be painted black or remade in stainless steel.)

I usually just use NAPA fuel hose, I haven't ever damaged a 5/16" hose by working it onto a 3/8 fitting. At least never damaged one that I could tell, and that stuff needs changed every few years anyway. When working conditions are tight I use some vaseline and a shot from my heat gun.

P-80 is the way to do this. Google p-80 and get a sample.

Brass Hose Barb Fittings

well, here's a liter for fifty bucks on eBay.

P80 on eBay

this is an excellent deal for P80, if its the real thing. i buy mine from apparent one-off liquidation sales like this. i got a half quart once for about twenty bucks, and then a liter for about twenty.

Since we're on the subject of P80, I'll take the opportunity to repeat my testimonial regarding the use of this stuff on fork gaiters. It's been a few years now since I've been using it, and the gaiters are holding up very well.

As to my original query, I've ordered barbed brass "reducing" fittings, 3/8" to 5/16". They're coming from China, so I'll be waiting a while for them, but that's ok; I'm not planning to install the oil filter until the riding season is over. For appearance's sake, I'll first try them without clamps. (There WILL be clamps on the oil filter spigots though.)

Thanks NickL and Jon W. for the tips on where to find these fittings.

Sticking a narrow hose on a slightly large end fitting can risk small shavings of rubber inside the hose, so be careful.
I have used a mug of hot water often, one quick flick throws any trapped water away and the hose is malleable for a few mins