Blue star oil pressure parts diagram or help please

Started by MJM_58SR, 22 April, 2023, 08:36:24

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MJM_58SR

Hello all
I wondered if you would be able to help me with a diagram of how the oil valve is assembled and what the parts are in a 250 blue star please. It's the one that sits on the end of the crank RH side and goes into the timing cover.
Thank you
Martyn

Steve.S

Hello Martyn, Good to see someone else with a 250 Blue Star. There are 2 oil valves on the timing cover. The vertical one is the Oil Control Valve and has the brass toggle on top. The other is horizontal and is the Oil Pressure Valve, and thanks to Bicyclerepairman I now know that this is to create pressure on the supply side of the system. It is threaded into the timing cover and secured with a locknut. The open end of the body is sealed with lead, and has either 5 or 10 stamped on it to indicate the pressure it has been set to. If you melt the lead, you will find an adjustment screw, spring and ball. If you can get hold of a copy of Bruce Main Smiths green book "BSA Motorcycles 1935 to 1940" ISBN 978 0950241272 there are diagrams showing the arrangement, but it's just a simple spring loaded ball valve.
I had to make up a little test rig with a regulator and gauge, and found mine was holding no pressure at all. So I fitted and reseated a new ball, and set it to 7lbs. Made a world of difference. Let us know if it's the Oil Control valve you mean. What year is the bike?
Steve.

MJM_58SR

Hello Steve
I would really like it but I have to admit, the bike belongs to a friend, he is an older gentleman (87) that has recently bought it at an autojumble as his other bikes are now too heavy for him but he still wants to ride, he says he hasn't got enough time to restore it so is going to get it running and use as is. it's a non runner at the minute but has had a fair bit spent on it by the previous owner who then seemed to have lost interest, the two things that need sorting are the rocker cover and the side casing is off the engine. Unfortunately parts views don't seem to be available!
It's good to be able to make contact with someone who has one, they are a really nice looking bike.
Thank you for the reply, the valve I'm asking about is  the horizontal one, I think it mates to the end of the crankshaft and goes into a recess in the cover so I think what you describe gives some good information to work on. I'll have a look to see if I can get hold of a copy of that book too.
I'll keep you updated on progress and I'm sure I'll have some more questions!
Regards
Martyn


Steve.S

Martyn,
If you remove the locknut, you will find the end of the valve body is squared off to fit a spanner. If it's seized, try a little heat.
The National Motorcycle Museum sell the BMS photocopy parts book and Instruction book. The Parts book is very well illustrated.
It would be good to know what year it is, as BSA redesigned the frame and engine for 1934 onwards.
I wonder what makes you think the Oil Pressure Valve is faulty?
Steve.

MJM_58SR

Hello Steve
Sorry forgot to add that bit, It's a 1934 registered bike despatched 1933. The side casing was off the bike and the parts in a box so it's a case of working out how to put it all back together!
Regards
Martyn

Group Leader

That little BMS book is excellent if you can find a copy.

This link might also be of use ......

     https://bsa-info.nz/parts-lists/#Various

Alan

Steve.S

If you search on ebay for item 175710535435 you will see a picture of a late sloper timing cover, showing the same assembled arrangement.
BTW, if the Blue Star was manufactured in or after September 1933, it is probably a 1934 model. This matters, because BSA redesigned both the frame and engine for 1934. Outwardly, I think the engines looked much the same, but the 1934 model had a smaller bore and longer stroke.
Of course, you can tell by the engine and frame numbers, but the 1934 model had a cast iron frame top member, and twin frame tubes under the saddle.
Steve.