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Oil Leak where right side crankshaft cover.

Started by Loukiii, September 07, 2023, 01:49:18 PM

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So when I went down back in march and slid on the right side, the crank shaft cover ground off as well as some of the engine casing. Somene suggested I just build up the missing metal with jb weld and put a new cover on. I did. But when I started riding the bike, I noticed oil on my right shoe and found some oil leaking out from behind that cover. So I put some liquid gasket on to seal it but that didnt really work. Then I got to thinking is there even supposed to be oil there to begin with. I mean there was no gasket there before. So there is a rubber cover that seals the crankshaft behind there and it looked to be a little messed up too and I suspect that is where the oil was coming from... So even if I sealed off the metal cover I would probably still be leaking oil inside the engine possibly?

Look at these pictures and tell me what you think.
If you look at the last 3 pictures you can see on the right side where the rubber cover looks to be messed up on the edge.

RPM - Robert

The case halves are machined to each other and have no seal between them. To seal the end of the crank, however, there is the crank seal that you see there. With the machined surface being damaged and the crankshaft seal being forced out of round you won't be able to seal that.

The metal "cover" is just a fascia or a beauty piece to not show the seal. It doesn't seal oil in, the crankshaft seal is what holds the oil back.



I put some liquid gasket over the damaged area. Maybe that will do it.

RPM - Robert

Hard to say from the photos but if you knew a skilled tig welder who could weld the aluminum back up and then a machine shop that could machine the seal surface back to the proper ID it may work. The other thing you would need to worry about at that point would be the welder getting the aluminum too hot and distorting that area as one of the set of main bearings is right there and this could cause a problem with bearing to crank clearance and thus could spin a rod bearing.

Also if you got jb weld in the area that is going to be welded it can be very difficult to get clean enough to get a proper weld.

Long answer yes, short answer probably not fiscally feasible. Sorry, for being pessimistic here.

I would look around for a local legends car track and talk to some of the legends car guys that have swapped to the new FZ/MT-09 motors they are dumping engines left and right for fairly cheap (Probably cheaper than what a welder would charge to do all that work) Then you can do one of two things. Put your head on the 1250 motor or modify the fins of the 1250 motor to fit in your chassis and bolt the motor up (Unless you can find a 1200 motor). T.Legg is in the process of doing this.

These will keep from ruining that area again and the ignition side as well if you do get it fixed.

Fingers crossed the liquid gasket works for you.


As you mentioned, welding near the bearing can introduce heat distortion, affecting bearing clearance and potentially causing engine failure.JB Weld residue can make proper welding difficult. Its removal is crucial for a successful weld. Welding might be technically possible, but the risks and costs make it a questionable solution.


The oil seal is compromised by the piece sticking out.

I would remove the old seal and clean all oil away. This can be done because there is a drain hole behind the seal. Install a new seal and then add some ultra black silicone around the rim once the new seal is in.

Im not sure if welding or epoxy is required. The bore that houses the seal usually doesnt get damaged enough to warrant that.

Randy - RPM
Randy - RPM