Oil Loss

crawsue · Post by **crawsue** » Tue Mar 27, 2007 8:49 pm

While checking my primary chain tension with the engine idling,I was surprised at the pressure of air exiting the chain inspection hole.Presumably this is designed "in" to help the crankcase breathe,but it must make sealing the chaincase a bit more dificult?I did read in a book on pre '65 British Trials 'Bikes that sometimes the factory drilled the primary chaincase to releive the pressure,and help lubricate the drive chain. I suppose the problem with that on a road 'bike is oil on the rear tyre.

Biscuit · Post by **Biscuit** » Tue Mar 27, 2007 9:12 pm

Checking the chain with the engine idling? Crikey, Crawford got some spare digits have we?

TommoT · Post by **TommoT** » Tue Mar 27, 2007 11:24 pm

quote:
...I did read in a book on pre '65 British Trials 'Bikes that sometimes the factory drilled the primary chaincase to releive the pressure,and help lubricate the drive chain. I suppose the problem with that on a road 'bike is oil on the rear tyre.

...few people would advocate drilling more holes in the primary chain case!!! But nice with a different perspective on a common problem! If anyone ever get their chaincase tight enough to keep any kind of pressure inside it, please let the rest of us know how you did it!

The twisters in the chaincase help the oil mist in there, getting everywhere, so to speak! So don't distract your otherwise clear thinking with speculations on micro weather phenomena inside a pressed steel primary chaincase

NB: Those extra holes would have been for cooling purposes, rather than lubrication.

crawsue · Post by **crawsue** » Wed Mar 28, 2007 7:13 pm

I was only "inspecting" Alan! No digits applied! The idea of a "breather" hole ,with pipe attatched,was tried in the mid 50,s by both AMC & Ariel,according to my book.A hole was drilled near the top and inside casing,and a peice of flexible tubing,probably fuel tubing,was pressed through and exited near the drive chain.The thinking was something to do with the very slow revolutions these "big plonkers" were being asked to perform in trials of the period.Releiving crankcase pressure below the piston was thought to make this easier to control.I'm going up to Kinlochleven for the pre '65 Scottish Trial in May,so will get lots of ideas about chaincase sealing there--no doubt.