What's this?

[Brett]

On the underside of the cylinder head, at the back, there is a metal tap which is pressed into the casing where the oil way is. Can anyone tell me what this is for?

After torqueing up my re-built engine a few days ago, I found it left on the workbench, so had to go back into the top end to install it. However there doesn't seem to be any reference to it in the Haynes manual, and I've only found one photo of it's position in Google images. Does it help direct oil flow? (the bike is a 1980)

 

[mrriggs]

It's a baffle to [help] prevent oil from blowing out the breather.

 

[Brett]

Ok, thanks, that makes sense. (I should have asked before I stripped the top end to put it back in - I may not have needed it!)

 

[KevC]

Or the breather itself ?
A picture always helps in identifying these things Brett.
Look HERE for a picture of both types of engine breather that can be fitted or HERE for the oil return baffle mrriggs referred to.
HERE is apicture of the breather fitted to the engine

 

[Brett]

Great links, very helpful, thanks. (I'll do that breather conversion)

 

[xschris]

How much better would this help the bike run? Any?

 

[5twins]

Don't open up your breather, you'll be sorry. All it does is cause more oil blow-by and increased oil consumption. It's a racer thing that our street bikes don't need. If you want to do a worthwhile mod to the breather, add the one-way check valve.

 

[Brett]

Will do, thanks for the advice 5twins. However I'd do anything to avoid unnecessary oil leaks - I should think the one way valve would sort that out. Do you have any suggestions as to the best valve?

 

[xschris]

My bike is not stock and burns no oil. I wonder if any one else has tried that mod?

 

[5twins]

Yes, you want to use a power brake check valve .....

We can get them in the states at most any auto parts store. I'm sure you have something similar available because this mod was started by the Brit bike crowd on old Nortons. They install the exact same part. I run pods so I position the valve over them. Any oil vapor or drips get recycled through the motor. Very little, if any, comes out and I've never seen a drip.

If you have the original airbox set-up, just splice the valve into the breather hose somewhere between the breather and airbox.

 

[Brett]

Great, thanks. I'm sure they're easy to get hold of here.