Breather plug

[red ghost]

On 4 strokes any unburnt hydrocarbons getting past the piston rings go directly into the crankcase, due to emission laws these were no longer allowed to be vented to air so are fed back into intake system to be re-burnt. On a 2 stroke blow-by does not get into the crankcase unless the drive side seal has gone so PCV would be a waste of time.

I totally agree and I should have been clearer in my post,I was thinking of going direct from the case to the air filter, no one way valve,just straight hose.

But now that I think of it,it may be a bad idea with carb spitback sending vapour to the case messing with oil

Must think harder

[red ghost]

I've thought a little harder and I think I'll give my ScootRS plug another go, this time I removed the 'swarf' packing and replaced it with a piece of green Scotch Brite pad and some fine stainless wire mesh,seems to pass air ok and will refit the plug and go for a run of the weekend. My alternative to Scotch Brite pad is some felt from the fuel tank drip tray, we'll see.