motor locked?

[ndp]

i was going down the highway enjoying the air when all of a sudden "CLUNK" is all i heard my baby died on me. the starter wouldn't turn over the kick was frozen. i bumped the starter several times then the kick gradually moved until it got to the point the kick began to move again. so i got it home and took the cylinder head off to see what was going on but to my surprise. what i saw was nothing like my 22r Toyota engine and i had no idea what i was looking at . i feel like my motor was locked or was it?..............i just don't know my bike rode fine until i started patching up my exhaust leaks and i also changed the oil. that's it someone said patching the leaks built up pressure and that's what killed my baby.    

[sidthesloth]

G'day mate, if it just locked up, the first thing I would be looking at is the CVT, clutch then I would be checking the generator rotor.
If you find nothing there, then I would be looking inside the engine. Now that you have your head off, how does the piston look? 

[Shaka]

It sounds like you may have seized the motor.  Once it cooled down the piston "shrunk" and it turns freely now.  That is caused by the aluminum piston overheating and expanding inside the cast iron cylinder which doesn't expand at the same rate as the piston.  The piston gets stuck inside the bore until it cools enough to contract back to original size.   Patching the exhaust could have caused this by restricting the flow of the hot exhaust gasses which cause the engine to run hotter.  You can solve this problem by making your fuel mixture richer and/or freeing up the exhaust.  Since you have the head off already, rotate the crank to BDC (bottom dead center) and inspect the cylinder walls.  If you seized it hard enough to lock the motor there is most likely damage to the cylinder as well as the piston.  Because it is a cast iron cylinder, you may be able to get away with just honing the cylinder, lightly sanding down any rough spots on the piston and replacing the piston rings.  A compression test will give you a good indication of the internal condition of the engine.  It should be a minimum of 100 psi to be able to run.  Ideally, you are looking for around 120 psi or more.

[ndp]

well the top of the piston is kind of dirty looking the rings look like the gap in them were stuck to the piston itself

[sidthesloth]

G'day Shaka, do you reckon a soft seize would stop with a clunk? Usually bog down and stall?

[Shaka]

well the top of the piston is kind of dirty looking the rings look like the gap in them were stuck to the piston itself

You may as well slid the cylinder off and check everything out real well.  I like pics!

G'day Shaka, do you reckon a soft seize would stop with a clunk? Usually bog down and stall?

You can't usually really tell when you soft seize.  You will notice it as a drop in rpm's usually while running WOT for awhile.  If it's bad enough it would stall the motor.  A hard seize will stop with a clunk to say the least!  From what I've heard you're lucky to keep it upright when it hard seizes.  Even after a hard seize it will usually free back up when it cools though, just does a lot more damage internally.

[sidthesloth]

Ahh see, always learning. Am about to pull the jug on mine again, will take some pics of the fix for loose oik pump.

[Shaka]

What are you doing still running an oil pump Sid?  Here's your solution right here:  http://www.exportstrength.com/product_info.php?products_id=621&osCsid=m4jdc41fs6n4r59qhptdsfrpt3

[sidthesloth]

G'day Shaka, sorry for late reply. I am still premixing, using the pump body to block the hole without the shaft.
That plug looks good but a bit expensive, would be nearly $30 Australian!!
Cheers,
sid.

[Shaka]

That sounds a little better!    I've got a thread on here somewhere about what I did to plug the hole on mine.  I just used a rubber expansion plug (freeze plug)  to block mine off.  I modified that bracket a little to hold it in place.   I have wanted to get that nifty little plug for the purpose of taking up the additional crankcase volume, but my rubber plug is still holding up just fine.