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Posted

What the hell is going on? Excuse my language, but a fresh rebuilt Hot Rod crank, blew up and melted the bearing and rod right off of the crank! Right side only. Left side still looks brand new. I'm assuming maybe a plugged up jet not letting fuel thru cuz the whole rod turned blue it got so hot! Any advice or suggestions?? Think the rest of the crank will be ok?

Posted
air leak or pluged jet i would say.

That sounds most likely.

Posted
I almost lost my faith in Hot Rod, but that thought quickly faded after joining these forums yesterday and searching and reading posts until 2 in the morning.

 

 

You just melted the piston right? The rod and small end are alright? Have some pictures?

Posted

we had a bike we bought that had gotten the lower bearing cooked and turned the crank and rod blue. Im thing it was just a bad bearing, but IDK becuase it was like that when we got it, and the previous owned didnt know jack about the bike.

Posted

when you replaced the crank di you do a leakdown to make sure the cases did infact seal? if not you could have an air leak, or its possible that you just got a bad bearing and cooked it. I'd lean more towards the air leak

Posted
You just melted the piston right? The rod and small end are alright? Have some pictures?

No pics, but not just the piston is melted. The piston actually looks like it held its ground during the overheat or whatever happened. The actual rod bearing at the bottom of the rod is gone, and the bottom of the rod, and surrounding metal is blue from heat. Motors out, not split yet, crank turns fairly freely. Left side piston, rod, bearing look brand new. Right side, not so new. The left spark plug looked tan to brown, and the right was like tannish-white. I knew it was blew up when I pulled the right plug. Would the piston be affected if it was a bad bearing. The top of the piston has a few pits and a couple areas around the edge on top appear to have melted slightly. I actually just got the machine (CHEAP) from a local guy but I know all about what he's done to it. He has had nothing but problems with it. I did not work on this motor yet. He got sick of it, now I plan on fixing it properly. Thanks for everybody's help by the way!! You guys rule!

Posted

Same thing happend to me. Lost left rod bearing and rod broke. Happend so fast, by the time i heard it and go the bike shut off it was too late. Cant bitch though, from what i could tell it was the original bottom end. 13 years old.

 

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