Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board B44 oil on cylinder

After coming back from a ride this afternoon I noticed a few drops of oil on top of the crankcase just behind the cylinder.
The oil appears to be not coming from the head gasket. It appears mostly between several fins along the studs on the drive side.
I’ve had the bike for many years and never had this problem, and have not done any top end work since last summer.
There is zero oil anywhere on the head or rocker box.
Where could the oil be coming from? I will clean the area and use talc to see if I can locate where exactly, but in the meantime, has anyone experienced something similar?
Thanks,
Adam

It looks like a head gasket leak. The oil is running down the stud bores and studs.

I would check the head stud torques before going deeper.

thanks Stuart, I’ll check the torque
So the head gasket is leaking only as far as the studs; Is the cylinder casting porous at the stud bores?
and does the presence of oil indicate new rings may be in order?

Also check the barrel crankcase joint, there are two oil drain holes that pass through the head, head gasket and barrel into the crankcase. Any of these joints can leak and in the turbulent air around the barrel oil will appear in the oddest of places well away from the leak. Oil can also come up the studs from this leak when its at the crankcase/barrel joint as the studs are exposed in the middle and not fully cover by the barrel, The studs screw into blind holes in the crankcase so very unlikely to be a direct leak up the threads much less appearing after some time.

A guy wrote to the "Agony Aunt " for some advise:

Dear Abby \

I have a dilema
I got off night shift a bit early and being a considerate chap i shut down the bike engine and crused into the car port as not to wake my wife. As i came down the drive I noticed my freinds car in the drive and only the bedroom light on .....It was then i noticed a small oil leak under my machine!

Is this something I can fix myself or should I take it to the bike shop ?

hahhhahahahhah ROFLMFAO


PS this isnt off topic as it is about oil leaks hahhaahah

I have 3 unit singles and they all leak out of the studs. Perhaps leak is too strong a word, ooze might be better. None of mine do it when the engine is running. Only when parked on the sidestand for more than a few days. Then I get a some oil on the fins.

Ed from NJ

I nipped up the nuts (thanks again Stuart) , and hopefully that will be the end of it.
Since I bought and installed a new rotor a few months ago (which replaced the 51 year old one) it starts much easier and seemingly runs stronger so I’d be happy to just ride it.
Thanks to all

Despite my best efforts, I never had a BSA that didn't leak from somewhere.
Mr Mike

I have DB34 and B50 which are leaking from nowhere.

I got a head gasket that was too thin once. it oozed and burned oil until the engine warmed up, then it would seal up and act normal. not something you would normally notice but once I put it next to an older good gasket, it was obviously thinner by a little bit. the barrel stands proud of the cylinder. the head can accommodate some of that but the gasket is the key to a good fit

There was a spate of pattern B40/B44 head gaskets that used a tinner gauge copper sheet than the BSA originals that led to these issues. It went on for some years so they could still be about.

This isn’t uncommon with A65 head gaskets either. Original ones were about 0.048” and the pattern ones about 1mm (0.039”) other differences too but the thicker ones tend to seal better IME.

ditto on the head gasket thickness ......... I got some thin ones in gasket sets from eBay, not much good and replaced with thicker ones from BSA Unit Singles.

Of course I made the issue worse by lightly flattening the heads with the good old fine wet and dry on a sheet of glass. It did actually need doing but I may have taken a tad too much off which made the recess in the head for the cylinder liner too shallow. This in conjunction with a thin gasket created "issues".
Re cut the groove, thicker gasket .... well annealed! ..... problems gone with a good seal.