Well, damn. I hate when stuff tears up. My '12 351 has been making some ominous noises from the bottom end for awhile so I decided it was time to do some investigating. Pulled the clutch cover off and nothing seemed adrift, oil filter is clean but I do see some metal flakes in the pre filter for the oil pump. Nothing to do but pull it apart.
The head comes off and all is good but the cylinder and piston have some heavy scuffing on the skirt. I pull the engine and split the cases to find the big end of the rod/bearing is shot-lots of radial movement. I'm surprised the piston didn't smack the head. I checked all of the other bearings and the only marginal ones are for the balance shaft. Now the question is does anyone rebuild the crank or am I looking at a new replacement? I need to call Bill and see what he can do for me on the piston and cylinder. Weird thing is that this started last summer when I installed the 351 kit. I even pulled the jug after I got it together to try and find the problem. I guess it was the rod bearing all along-really amazing that it lasted as long as it did because I didn't baby it.

 

Man, that's a bad deal. How many miles on the engine?

 

EWWWW! ....do you have all stock parts? maybe take your aftermarket stuff off, sell the bike, and buy another...unless you think you can handle replacing a crank. That's a lot of work.

 

Sorry to hear that!

 

That sucks!! Crap; guess when I pull mine apart to do the ported head, I'll pull the jug off again and check the rod bearings just in case.

Rob

 

+1 on "that sucks" good luck with it.

 

I installed the kit when the bike had about 1200 miles on it and she is at 4800 now. I have found a couple of places that may be able to work on the crank but if not it looks like about $400 for a new one(ouch!). I still have to contact Bill and see what he can do for me on the cylinder and piston(have mercy on me).

 

What kind of oil do you use?

 

I would check the oil pump to verify that it is working or not plugged up somewhere. Possibly replace it too. Sounds like something was not working properly.

 

About 37 years ago I ruined a crankshaft on my hot rod. While dropping in a new cam, I somehow got just enough threads from my shop rags - which were used to cover and protect intake ports, much like we do when pulling our KLX's apart - into the engine that they partially clogged one crank journal - eventually "throwing" that rod.