After many delays, not least moving to a new home, I went for a brisk 25 mile ride on my WM20 yesterday. It ran well, pulling strongly in the intermediate rev range as you'd expect from 712cc with intake tract work. No piston seizure this time!

What did happen was excessive oil discharge from the crank breather. The chain guard, rear frame, and rear wheel are soaked in oil.

It has a fresh bore and TotalSeal gapless rings. I can stand on the kickstart crank for over 1 minute on compression without detectible leak-down.

I'm thinking of installing a second breather in the tappet inspection plate and running the lines to a catch bottle, but that's just a bodge. Can anyone help with advice?

Jeff Bandola, Rhode Island.

email (option): jjbandoo@aol.com

If it had been standing for a while maybe you had a wetsump problem? That oil would find it's way out of the crank breather until the pump cleared it.

Cheers
Pete

Hi Jeff..Peters comments are relevant and something you need to determine..The amount of oil may well point to that....

I have found that the standard breather was adequate on an 'M20' 720 that was basically standard in other respects...

However, my B33, which I have enlarged to the same capacity and which revs harder, required an additional breather to stop it leaking...

Saying that though, the oil was not all coming from the breather...

I have found the breather will pass a little more than the expected amount of oil for a couple of hundred miles until everything beds in but not anything like as much as you describe...Ian

email (option): ian@wright52.plus.com