XB rocker covers on an XL Buell engine



The benefit of doing this is greatly improving the engine’s breathing ability and therefore reducing the amount of oil puking out of the heads, a subject near and dear to every Sportster/Buell owner. A side benefit is the “cool factor” of having new XB parts on you old tube frame Buell.

The pictures below helps to explain why this new cover works better than the old one. First you are getting rid of the spacer, eliminating one more gasket that could leak, but more importantly it gets rid of the tiny return hole (2) and replaces it with a bunch of empty space in the top of the head.. Second, the PCV valve is much larger than the little flapper valve used previously so it can handle more volume in each head. Third, the air oil mixture only has to go up through top of the head through the PCV valve and never return, where the old design had to go through a wandering route as shown in this figure from the service manual, increasing the chances of oil pooling and puking when the engine decides to push the oil out of the breather bolt.

The old way

The New Way

Here are the parts that you will need:

Rocker cover, front head $39
Rocker cover, rear head $39
Grommet, Viton, Black $2.95 each (need 2)
PCV Valve, $6.90 each (need 2)
Hex Socket Button Head Screw, $4.75 each (need 2), not shown

The only special tool that you really need is a cut down 3/16” hex wrench. Take a regular hex wrench and cut off about ½ inch of the short side of the wrench. What this allows you to do is to remove the hex bolts that are obstructed by the frame on the rear cylinder.

After removing the fuel tank, you might want to consider removing the top and the front two tie bars and the front motor mount to rotate the engine down away from the frame to give you more space to work in. Don’t forget to put a jack under the engine so it doesn’t drop on you when you undo the front motor mount. Slowly lower the engine using the jack until the motor mount gets close to the front tie bar frame member. I found that the extra space to work with was helpful.

The operation is basically take off the four bolts holding the covers, remove the cover and the spacer, then install the new XB cover and bolt it down with the same four screws. The only two clearance issues that I ran into were the front cover and the front motor mount and the rear PCV valve and the Fuel tank.

Now, what do you do about the old breather holes in the head? Just use the two button head screws that you have not used yet to replace the old breather bolts, remembering to use thread sealant on these bolts.

For the front cover, I shaved away some material from the front left corner of the rocker box cover so it would clear the front motor mount during installation. On my bike a friend of mine had cut down the edges of the head hex bolt in that corner to provide further clearance when removing and installing the covers. You can also completely remove the front motor mount, but I did not want to mess with it.

For the rear PCV valve, I found that by pointing it towards the rear of the bike and some creative filing there is just enough clearance between the top of the PCV valve and the bottom of the tank on my S3. I’ll keep an eye on this area to see if further modifications are needed.

Finally, you can send the two hoses separately or tied together like I did into a catch can, or just into the ground like I did here, next to the tank vent. This will ensure that the side stand switch and hinge are always properly lubricated!
So that’s it! The fun part now will be to see how long it takes your Buell friends to notice that your bike just looks “different” somehow.