426 left engine case cover same as?

Anyone know if a 426 left engine case cover is the same bolt pattern and size as a 450(the one with the oil fill hole)? I've got a Graves Oil/Air separator tank kit that I thought I could make work on my 426. But the 426 timing plug and 450 oil fill are not the same. If i can't get a 450 left case cover to work I'll have to find a smaller fitting to then drill and tap my own hole in the case cover. Then again, finding a left side case cover for a 450 may be about as hard as getting the fitting and drilling the hole in the 426 cover. Just wondering about options really.

Give you and idea of what I'm talking about on the drain back plug.


They are not the same, and cannot be interchanged.

Drat! I was afraid of that. Off to look for smaller fittings I guess. Thanks a lot grayracer.

I just drilled and tapped my cover ('02 426) for a 1/4" NPT hose fitting. There is enough material to easily accept the threads. I built a poor man's version of the oil collector, but I am using a 1/2 hose from the cover to the bottle. After having a great conversation with Tryce (Tdub) about breathing issues on these bikes, I feel that venting from both the top and bottom is a good idea. Tryce mentioned that his 426 vented about 12 ounces of oil when he ran the Springfield mile, and since I will be using my 426 as a Supermoto weapon, and expect to see sustained high revs, I followed his advice and am just venting the dickens out of the engine. When I split the cases next time I will be looking for a spot above the transmission to install another vent, in lieu of the top of the cam cover.

Thanks for the tip pscook. Where did you put the fitting in the cover? On that topside angle? Or on the flush side?

Thanks for the tip pscook. Where did you put the fitting in the cover? On that topside angle? Or on the flush side?

I put it at 10:00 as you are standing on the left side of the bike looking at the cover on the biggest flattest section. I will try to remember to take some pictures tomorrow when I get a chance. I bought an aluminum hose barb, 1/4 NPT X 1/2" hose, tapped the hole and trimmed the length of the fitting to just proud of flush when threaded all of the way in. It's pointing right at the flywheel, with quite a bit of room to spare. It should help the engine vent, plus the oil has an easier path back into the engine. I then vented the top of the bottle into the airbox, so that any escaping vapors are contained and consumed by the engine.

About here?


A friend who works at Widman Suzuki helped me out on the drilling and tapping. I found a decent brass fitting to make work, but he added in the chrome elbow to make this a bit easier to hook the hose too. And to add one more color to the area :p I think it worked out pretty good. I'm not done yet, still gotta zip tie down the hoses to the collector, and receive the WR type elbow to add to the bung in the top of the air snorkel. but I did get away with flipping the Graves bracket and getting it to fit on my 426. I moved the clutch cable out just a bit for clearance. I think it all worked out pretty good.



That looks pretty neat and tidy. My fitting is 90 degrees from that, just a little forward of the upper plastic plug on the upper forward facing surface.

Thanks. I considered putting it there, but was worried about clearance to the rotor within. I'm told it has a WR rotor for running lights when it was a trailbike.

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