AJS 350 16MS Crankcase relief valve

[StevieL]

Hello Gentlemen,
since owning this 1955 A.J.S. I have had oil dripping out of the crankcase relief valve,

with the engine at idle its a constant dripping, if I raise the engine speed it is worse!! and with the engine stationary the oil drips slowly for a while but almost like a syphon effect and then stops,

I have recently replaced the primary chain and dynamo drive chain and took this opportunity to remove and repaint the tin backplate, this is when I discovered that there was no pipe attached to the relief valve adaptor !!

I have fitted a new diaphragm but the oil drips the same.

The engine runs and rides fine with no exhaust smoke, but I am puzzled as to why I have this problem.

I would appreciate anyones thoughts and experience in this area.


thanks

Steve

[clive]

I would suggest thus is pretty usual with a worn engine. Bit of blow by round the piston and the extra pressure blows a mist of oil from the relief valve. To reduce the tendency to cover the rest of the bike with oil I have attached a short rubber pipe to mine to allow it to drip free of other components. I think a rebore may be needed to stop it. On one bike it was significantly worse after an over heating seizure partly restricted the expansion of the rings in their grooves. But you could see smoke rising from behind the primary chaincase at tickover when the engine was hot and the compression was down (a 500 it still pulled the double adult Sidecar though.)

[StevieL]

hello Clive, thanks for your comments and advice, I think I will keep running this bike as it is and monitor the amount of oil that it blows out.

I may decide to take the engine out at a later date and fully overhaul.

thanks again Clive , much appreciated.