Yup. I don't know what set of conditions it would take to get that much oil into the boxes, enough to reach the umbrella seals (which are at a high point), and get forced out into the carb or onto the pavement. I've had similar times when I've 'lost' 1/2 quart of oil, and on the same ride, I've 'lost' none. Weird.

Let's face it, the MoCo design of the three piece rocker boxes is so-so at best. Probably the various failures over the EVO production, motivated them to change it.

I won't even get into the oil drainage design from the heads. As there are a helluva lot of EVO engines still laying down the miles. And a helluva lot of those engines with leaking base gaskets and oil puking out the breather.

Sorry for the hijack OP....

 

Was advised that it was the vent restricted so I took the banjo bolt completely out last time. It didn't blow out the gasket this time, just dumped it out the enlarged vent hole. It has done it running 70 or 80 on the hyway but also once just running around 50 in town. Doesn't seem to be consistent at all. I can make the same ride a few times with no problem, and then it dumps a quart or two in 10 miles! After the bike cools down it stops for a while, but then suddenly comes back. Any advice would be appreciated.

 

Did you replace your umbrella valves?

 

Are you overfilling the oil level?

 

Both heads need breather bolts to vent heads or gasket blow out will occur.

 

Did you check to see if one of the rocker box covers was warped? Like I posted earlier, I've got a loooooong painful story about warped rocker box covers.

 

No, they looked ok. Are they a likely culprit?

 

I thought mine were "OK" too until I decided to replace them during the rebuild, and then I realized just how stiff they were. Something is keeping your heads from breathing properly, whether you don't have banjo bolts for your air cleaner mount, or your umbrella valves are stiff and aren't moving... something is holding the pressure in. When it can't breathe properly, it's going to find somewhere else to do it. Just a little thing I'd check you know?

 

The friend I bought it from put a new rocker box cover on it right before I got it. But then, that was 5 years ago. Will check it next time I have the cover off.

 

Does your aircleaner mount have the banjo bolts? One thing you could test (even though I think you did) is to pull out one head bolt for the air cleaner at a time, run the bike, and feel for airflow. You should feel air and maybe even have oil come out for both of them. I tested this on my bike when it was pissing oil after the rebuild.

Man I wish I was still living in Houston right now... I'd be 5 minutes from you.