BSA B25 Starfire Oil weeping from gear and Kickstarter shafts

[AltcarBob]

Hello my first post so if I seem stupid that's because I am. Bought my first ever British bike a few months ago a 1969 Starfire I haven't had much time to ride it but l have noticed a leak from the timing side and after wiping up I realised that oil is leaking from the gear and Kickstarter shafts where the shafts come through the casing.

I have read the Haynes manual which is not much use and I have skimmed through the Rupert Ratio book but not had a chance to read everything yet.

Before I start unbolting things is this a common fault and is it possible for a newbie to fix it without any special tools. I bought the Starfire to learn about Brit bikes and boy am I at the bottom of a steep learning curve.

[Spaceman]

The gear lever shaft has an O-ring behind the cover to keep the oil in while the kickstart has a lipped seal in the outside part of the cover. The latter can be changed without taking the cover off but the gear lever O-ring can only be changed after removing the cover. The cover can be easily removed but it means removing the contact breaker mounting plate first and then re-doing the ignition timing once its all back together!

[DAVE BRADY]

Hi,

It may be worth checking the gearbox oil level as too much could overwhelm the seals.  Also, I think the filler/dipstick has a groove in the thread and small hole through the top to serve as a breather.  Although gearbox oil does not get that hot, if it is blocked and the box is a bit overfilled there could be a slight build up in pressure again pushing oil past the seals.

Dave.

[AltcarBob]

Found the problem the timing side was full of oil. Loosened the cover bolts and pushed the clutch lever to break the seal and a tidal wave of oil gushed all over the shed floor. I need to get the exhaust and footrest off and investigate further.

Oh and just to put the hat on it I checked the gearbox oil level and the dipstick is dry I think the gearbox has drained into the side

[Spaceman]

The oil is sealed inside the gearbox by the outer timing cover - if you break the seal, the gearbox oil will inevitably flow out! Since you will now need to take the cover completely off, you might as well change the lipped seal and O-ring at the same time.

With the cover off, you will see that there are two compartments under it. The rear part gets full of gearbox oil and the lipped seal is what keeps it from leaking past the kickstart shaft. The front compartment gets a certain amount of engine oil blown into it via the camshaft timed breather. At the rear top of this compartment is an outlet to the little tube above the gearbox which is the engine breather pipe. Normally, the small amount of engine oil that gets into this compartment is allowed to slowly drain back into the sump via a small hole at the bottom. If it gets blocked, you can then get too much oil building up in the compartment which could then leak out past the O-ring so worth checking the hole is ok.

[AltcarBob]

Thanks for the information guys. I will order the lip seal 57-2641 but I can't find the parts number for the gear shaft o ring I have looked at the parts catalogue and the only o ring I can see is number 68-289 o ring oil feed it's page 17 of the parts catalogue headed gear cluster plate reference no9.

Is this the o ring I need

[Spaceman]

Sorry - my mistake. I thought I remembered BSA having fitted a seal to the gear lever shaft (quadrant) to stop oil leaking past it but clearly they hadn't!

I honestly don't know what keeps the gearbox oil from weeping out along the shaft. It may be that the oil level is lower than the height of the shaft or it may rely on the oil being too viscous. I'll have a look in Rupert Ratio Vol. 1 (the BSA unit single Bible) to see if he comments on this.

[Spaceman]

I think the answer to the question is that the gearbox oil level, when correctly filled, should be just below the level of the gear lever shaft. However, if you over fill the gearbox then the oil could weep out past the shaft.

Oil will still get splashed on to the gear lever shaft when the engine is running but in practice very little of it normally seems to seep through to the outside of the outer timing cover. Although the B25 engine design can be traced back to the Triumph Tiger Cub engine, that engine used a felt washer on the gear lever shaft to stop oil seepage but BSA never adopted this?

[ChrisG]

Sorry for the delay in responding to this but are you sure it was Gearbox oil? The smell is the giveaway.
I had a problem with my B25SS a few years ago. It had been standing for many years before I got it. It was OK when on the side stand but when on the centrestand it leaked out of the gearchange shaft. When I checked the engine oil level I found that the whole lot had drained into the chaincase. Reason - the previous owner had removed the ball and spring anti sump check valve so there was nothing holding it back. I fitted a new one and all was well.
Why the previous owner had removed it I'll never know. Worth a check?

[AltcarBob]

I have removed the anti Syphon valve and the ball bearing didn't look very good it had turned a brown colour. The spring and ball are replaced with shiny new bits I also checked the pressure relief valve and that was the same a brown ball bearing and a saggy spring.

I have cleaned the valves and cleaned out the drain hole blown them through with brake cleaner and compressed air.  Everything seems clear I am just waiting for a new clutch push rod and I will bolt it back together and check the bikes continence by filling gearbox first check for leaks then fill oil tank and check for leaks.

[chuckhaz]

Did you ever find out why the oil was coming out the gear change shaft? I am having the same problem and can't find an answer? My bike was returning oil properly and after a longer ride it emptied the entire oil tank into the engine and out the shaft.

[Tigerfeet]

How long was it parked for before you noticed this?  If it was a week or so, your problem is wet sumping. If it was a few minutes, then it sounds as though your oil pump isn't scavenging properly.

[chuckhaz]

It was not parked at all I was running it after rebuild to set idle and the took a ride, after a couple miles I noticed oil was pouring out at gearshift lever. It was returning oil before I went on the ride. Either the non return scavenge valve got stuck closed, pump got a blockage or it quit working. Trying to figure out which it was.

[rhyatt]

Peculiar,
So, it was running and returning oil before you started the run, then stopped returning oil during the run.
Surely there's a few reasons,
1 pump seized due to ingress of something
2 pump not being driven due to worm drive on crank
3 blockage in return pipe

But , if it was working enough to suck oil from the tank and fill up the engine , then 1 and 2 don't count

Tried dis one ting the return pipe and run the engine , put a dummy pipe on return connection momentarily

[rhyatt]

Disconnecting should have read !