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Just took apart my toy(mmmm...motorbikes)(Click here to view the original thread with full colors/images)
Posted by: -RD-
I currently have two bikes, both are old as fuck, both are Yamahas and both are red/white. The bigger one, FJ1100, is in running condition, but the toy I bought for 650e, RD350lc YPVS wasn't, and I finally decided it's time to see why.
And I know this shoulda been done with pictures, maybe next time 
Anyway, The Stroker wasn't running. Or it would start, briefly, and then drop the other cylinder cold and try to choke the other one as well...I'd done anything and everything to the bike outside the engine already, so a tour to the heart of the beast was in order.
The thing I love about old bikes is the simplicity, and that you have plenty of room to do whatever you need to do with them. First time I took this bike apart though, so it took me around 6 hours until the engine was on the table(and since my right shoulder's been operated recently, I had to get my friend to lift it there)...and it brought back plenty of memories, my first bike was RD125lc afterall, 6 years back...this is just a bit bigger 
Anyway, after I'd got the cylinders and heads out, it became pretty clear that overhaul was in order anyway...there were no signs of seizing recently, but the pistons were way overdue and the clearance was huge. The problem with running however, wasn't cause by nothing else than a failed crankshaft seal, on the clutch side. Both chambers were filled with the wrong kind of oil!
For those to whom it's not obvious what this means; while a 4-stroke engine breathes in through the head by the intake valves, a 2-stroke engines breathing process goes pretty much like this: When the piston goes up, air-fuel-2-stroke-oil -mixture gets sucked into the crank chamber, where it lubricates the bearings, and when the piston comes down, gets pushed through the ports in the cylinder walls to the compression chamber.
The crankshaft seal keeps this mix apart from the ordinary engine oil that's lubricating the clutch and transmission on the other side of the engine. Now that the seal was gone, the crank chambers were filled with oil that's not made to burn, so the engine couldn't breathe in enough fuel to ignite both cylinders, barely even one. In effect, it was as if a 4-stroke engine lost the intake head and the valves stopped opening.
Easy enough to fix, but the machining and new parts take money, so I'm forced to save for a while until I resume the project. I'm still hoping to be able to pollute the golbe with blue smoke in the soming summer though ^^
Posted by: xoshade
Should have included pix. 
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