I have a 94 evo that I recently put new rings in and had a valve job done. Since then the front rocker box gasket has blown out 3 times after just a few rides. When it happens oil blows out all over the bike and me. It is obviously getting too much pressure in the rocker box. Machine shop put new valve stem seals.
No leak at all in the rear rocker box. Any suggestions would be appreciated.

 

What air filter are you running?? Not sure how familiar you are with the bike, but the bolts that typically bolt the carb to the heads are where it breaths from.. Make sure the banjo bolts are installed correctly and its able to vent..

 

HGM Your reply made a synapse fire in my model T brain. The bike has an edelbrock carb and I had to fabricate brackets from 1/8 aluminum. One of them
is held on by the banjo bolt of the front rocker box vent. Seems likely that it changed the alignment of the holes so that it is not venting. Thanks!

 

now that sounds like a easy fix , & your just east of me & south of throttle jocky

 

While that is 'possible', I would more likely suspect a warp rocker box cover. I have a long and depressing story about warped covers on my EVO...

 

I've heard of this as well ,just never seen one myself

 

Generally, it is the middle or top cover that warps.

Always check the covers for warpage before re-assembly. Easiest way is to use a piece of plate glass and put the cover on it. See if it wiggles. They don't have to be 'off' by much to blow the seal/gasket out.

Aftermarket covers (non-S&S), seem to be the most likely to either warp or be warped when new. Yeah, check new covers too, mine came from Custom Chrome and they were warped. Best bet is to get Genuine HD. Good news is they sell them individually, so you don't need to pay for a set if only one part is warped.

 

I recently bit the bullet and bought new rocker box covers after replacing gaskets three times and only managing to slow the leak rather than stop it. I went from oil all over everything to oil all over just half the bike before I gave in and accepted that my covers were warped and no gasket in the world was going to fix that leak. Presto - no more leak!

 

What is really the stinker, is that on my bike I could ride it around town, and it would barely show any oil spewing out. So I asked a gray beard Harley mechanic (that has forgotten more things about HD's than most techs will ever learn), and he said simple: At highway speeds (60 MPH and above) there is a LOT of oil in the top end of the EVO. Too much oil, not enough drainage + a bit of pressure = Oil mist spraying past the gasket/seal on warped covers.

Also a good way to check after discovering the leak, is to warm the bike up, then let it idle. Run your hand around the rocker box covers. On mine, you could feel the air being pushed out.

Like you determined (and I did too after seven gasket changes over a four year period), there is very little you can do when the box is warped.

 

I absolutely buy that.. Both my bikes "consume" a fair bit more oil with my typical highway riding, than if I'm just cruising the back roads.. Rather than actually consuming or leaking out the seals, its carried out the breather on mine..