Wayne's 52 B33

[WayneBergman]

I have recently acquired a 1952 B33. The bike appears to have had very low miles after an older restoration. I am new to British bikes and the pre units and also new to this forum. I have an oil leak that is coming out of the primary casing, its flowing from the opening in the primary that services the clutch to the main drive sprocket. Only really seems to  leak when it's running and the leak  seems to kind of  pulse so I figure its source is a crank shaft seal that is letting oil and combustion pressure into the primary.

I drained the primary today and it had 6 oz of oil in it and I think its only supposed to have around 2 oz so I figure engine oil is leaking into the primary and then looking for a place to leak out. I realize I should take the primary cover off and have a good look in there while its running to see how much oil is coming out the crank shaft seal but as the primary cover is really stuck on there  I am thinking of a bit of a different option.........

I am wondering how much oil is really needed in the primary case anyways? If I just look into the inspection port every ride or so and if the chain looks lubed maybe I am good to go and just make sure I top up my engine oil levels often as I am sure some of the engine oil is leaking into the primary. If oil starts to leak bad again out of the primary casing I could just drain it from time to time and hope that a smaller amount of oil in that primary chain area is enough to lube the chain but not enough to spew out on my driveway. So kind of a two part question....

1- how will this effect the clutch? Does it need more oil than just a bit of misting from the leaking engine oil in the primary?
2- I am running 50 weight motorcycle oil in the primary, gearbox and by default in the primary as well. I have not long trips only short 50 mile trips from time to time and thinking this as a work around instead of wrestling with the primary removal and fixing all the seals etc. Any advise appreciated.....wayne

[berniej]

Hi Wayne,

That's a really nice looking bike you've found so firstly congrats!

I'm wondering if the excess oil in the primary is the result of wet-sumping. If there are no valves/taps on the oil feed from the tank (and there aren't unless someone's done the mod) then when the bike is standing for a while oil leaks through the oil pump, into the sump and can then overflow through the main bearings into the primary. How long 'a while' is depends on the conditiion of the pump and viscosity of the oil.

It can be prevented by fitting valve/tap but these carry the risk of failure or forgetfulness which could cause oil starvation and serious engine damage - it's a common topic of debate with opinions divided. I fitted a valve on my M21 to fix the same problem.

I also only put enough oil in the primary so that the chain is just submerged at the lowest point to make sure that some oil gets splashed about.

I run in these engines using old-fashioned mineral 20/50 and then switch to semi-synth.

Cheers,
Bernie

[Dennis49]

Hi Wayne, I have a B31 which looks nearly as good as your B33.
I am sure there are many wiser BSA owners than myself, however here's a few thoughts.
On the timing case there is a breather, where does it drain to? Mine drains into a little bottle cable tied to the frame.
I notice the reply about wet sumping, If it smokes heavily on starting, then clears  it's possible it's wet sumped.
Easy check is before a ride drain the sump, there will be a little oil but shouldn't be a lot.
Primary case is probably stuck on with silicone, I use it as well as a cork gasket, It can be tricky to remove the chain case.
Real issue is the lack of a proper seal behind the clutch. There's no real seal owing to having to move the gearbox to adjust the primary chain.
Just a large piece of felt.
Does the leak spray oil over the back end?

[idie]

The B33 engine doesn't have an oil seal on the crank. If it wet sumps and they tend to do just that it will over fill the chain case. As said you only need enough oil to reach the chain. 50 grade oil is to heavy for the primary chain as when running it will just make a channel in the oil. You need 20 grade as recommended. I have an M33 and have no oil leaks from the chain case. Use silicon and take your time when refitting.

[WayneBergman]

Thanks for the nice commets on my bike guys and also for the tips on the primary. Yes I have read about the wet sumping and I have fitted one of the new type sump plates with the easy to remove drain plug at the lowest level of the sump so I drain that back into the oil filler tank at first start up of the day.

I did not know however that the wet sumping would flow into the primary through the crank shaft so I am sure when the bike sits for longer periods of time it overflows then into primary like you guys say. This explains a few things so thank you for this.

A question remains however , lets say I keep the primary pretty much empty (if I have not started the bike for a couple of weeks I may drain the primary at the same time I drain the sump) but my question now is will the clutch be happy with just a min amount of lube on the chain. Is the clutch a wet clutch and will I know if I am causing the clutch any greif if I dont have enough oil in the primary?....thanks a bunch....wayne
Also Dennis thanks, and I will look for the breather to see where it goes.

[JulianS]

Dont forget that the chaincase oil lubricates the engine sprocket cush drive as well as the chain.

[idie]

Keep enough oil in the primary chain case to lubricate the chain, cush drive and clutch bearing.

[MGI]

Phil Pearson, who knows a little bit about the B series engines, advised me to put enough oil into the primary chaincase  to just cover the smooth part of a zip tie (before the locking serrations begin) obviously there are different sizes of zip tie but it needs to be one which is long enough to reach the bottom of the case when inserted into the oil filler hole!

[WayneBergman]

Thanks again everyone, I am learning stuff here so this is great. Dennis to answer your question on timming case breather it just kind of hangs down between the right side of the frame and the timing case cover, i may follow your example of fitting a catch bottle to it. Not sure how much oil comes out of that breather but I can't imagine its a good idea to be misting onto my rear tire. 

I figure at this point the plan will be NOT to pull the primary cover and hopefuly see how much oil is wet sumping or just escsaping into primary by looking into the inspection port with a home made dip stick of some kind. Then if i can minimize the primary case leak by keeping oil levels lower in the primary by occasioaly draining it, I think I will be happy enough with this. .....wayne

[Dennis49]

Hi Wayne, Thanks for the update, my breather pipe was oiling the rear chain and the tyre. The small amount that the bottle collects bears no relation to the mess it caused to the bike.