1933 Blue star front chain lubrication.

[Jean-Luc]

Hello all !

I can't find any precise information describing the front chain  lubrication system, if any of course...
She is a 1933  350cc Blue star.


Thanks !

[Steve.S]

I imagine it's the same as the 250 Blue Star. This has various drillings in the crankcase wall, which connect with the end of the threads for the lower chaincase mounting stud. The stud is part hollow and drilled at a right angle to allow oil to drip onto the chain. There is either a knurled adjuster, or an adjuster with a locknut located vertically behind the cylinder on the left hand side.
As an aside, it always sems to me that since this is the engine breather, the drillings are quite small, and BSA recommended turning the adjuster down to prevent oil entering the clutch, this would result in excessive crankcase pressure. The only saving grace would be the pressure being released into the integral sump.
Anyone got any thoughts on this?

[Jean-Luc]

Thanks Steve for this precise answer .

The "adjuster with a locknut located vertically behind the cylinder on the left hand side"  is in view .

I found the adjuster 2 turns unscrewed .
My chain case area was a real mess, leading to oil being spread liberally any time I stopped the engine.
Clutch slipping tendancy too...
The oil consumption was high too, although it may not be the only reason !
It is now 1/2 turn unscrewed from closed.

What to think about my new adjustment ?


I have found and read your very instructive topic too .https://www.bsaownersclub.co.uk/bsaoc_forum/index.php?topic=14949.0;prev_next=prev#new
I hope to manage reducing excessive smoking, and oil consumption.

Thanks again.

[Steve.S]

From what you say, it sounds like you are over oiling the engine. I would start by removing the brass adjuster knob on the timing cover, and screw in the splined adjuster, counting the number of turns until it bottoms. BSA recommended from half to one complete turn out. If it was set at more than this, you are probably over oiling your engine. Hopefully this will give you around 8 lbs/sq.in. on your gauge and a puff of blue smoke from the exhaust when opening the throttle after going down a short hill with the throttle closed......assuming your rings are in good condition. If there is no smoke, you are probably under oiling.
It might be an idea to empty the chaincase trough by stuffing a rag in there to soak up the oil, and drain the crankcase. This will allow you to start from scratch.
I think your adjustment of the oiler is OK, but I wouldn't turn it down any further.
You'll probably find that the friction ring behind the chainwheel is covered in oil. I've never had any luck cleaning oil off the rings, so replacement may be the only answer, but only after you have sorted out the oiling.
Incidentally, later Blue Stars had a chainwheel which enclosed the clutch with a steel ring, presumably to prevent oil getting into the clutch, but this won't stop oil getting onto the inner disc.
Let us know how you get on.

[Jean-Luc]

Here is what I have.

[Jean-Luc]

Thanks Steve for these precise and very useful answers.
I have adjusted the devices as advised.
I now have to ride the bike and see how things have changed.

And I'll let you know.

[Steve.S]

Jean-Luc,
Good to see you have the later enclosed clutch basket. This should help.
Let us know what your oil pressure is / was.