1981 sr250 engine problems

cack

New Member
so i've been working away at a "quick" little sr250 tracker project over the last few weeks, got the bike for free and just wanted to change it up a bit.

it started when i got it but had a tick in the motor around the cam chain.. sat around for a bit while i cleaned out the carbs, did a new seat, bars, lights etc.. but today i put new gas and a new battery in it, and started it up, fired up right away.. hoped on and did a quick rip around the block to see how it was running, everything seemed pretty normal, a little sluggish but nothing major.. while i was sitting in the driveway about to turn it off it stalled on me, but it was different than a normal stall, after it stopped running it sounded like the motor still free spooled for a couple rotations

took off the cam chain cover to take a quick look and there was a chunk of metal broken off something sitting on the edge of the cover, about 1/4 inch big, the sprocket looks to be fine and the chain is still in one piece, and still has pretty good tension.

when i try to start it now the motor just spins but it doesnt fire any more

now i'm just looking for suggestions on where to start looking to see wtf has broke on me and figure out how much this quick and cheap project is gonna cost me
 
after tearing apart the top end of the motor i've found out that the lock nut for adjusting valve clearance fell off and stopped the cam from spinning, which in turn sheared the sprocket off the cam shaft...

so...now im on the hunt for a new cam shaft for a reasonable price.
 
Brutal. Sorry to hear that mate.
Hopefully you can source a cam shaft from somewhere.
 
I had a spare sr250 motor in my truck today, delivering it for a friend. Made me think I'd like to have a spare myself...
 
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