93 XP 657X Engine noise after replacing pistons - now won't start

[jfatica]

Recently replaced the pistons and rings in a 657X engine from a 93 XP ski.

Once the engine was put back together, we checked compression, and both sides were at 120-130psi. Took a while to start the first time, but it eventually started running. The second time we tried to start it, it made a clicking noise like there was some serious resistance. We took the plugs out and tried, this gave us a steady click.

The pistons are moving up and down, and the crankshaft is turning.

Here is a short video with the plugs in
http://www.youtube.com/watch?v=f2vcmpbtxew&feature=youtu.be

Here is a short video with the plugs out
http://www.youtube.com/watch?v=qy-leMbba0E&feature=youtu.be

What could be causing this noise?

 

[jfatica]

Started pulling apart the engine. Rotary valve was not spinning. Upon further disassembly I see that the gear on the crankshaft had slid to the side again and chipped the other gear on the rotary valve shaft.

This is the 2nd time this gear has moved out of place. First time it happened, we had a shop put it back in place. Not sure what keeps causing it to move out of place.

This seems to be an issue with the design of the crankshaft. Do newer rebuilt crankshafts for the 657 have this gear secured in place?

 

[smc0922]

Gear on the crankshaft or on the rotary valve shaft? Crankshaft gear shouldn't move at all. RV shaft gear is spring loaded and should slide on the shaft.

Post a picture if you can.

And that compression is still very low for a new top end.

 

[jfatica]

Crankshaft gear
https://lh3.googleusercontent.com/-...I/AAAAAAAALZ8/xPssLeSTJ30/s512/1013121536.jpg

Rotary valve gear
https://lh3.googleusercontent.com/-...ALmA/yOZVtjpAJu4/s512/IMG_20130512_162709.jpg

 

[Thumper3322]

What he said, shouldn't be slipping. Might need new parts for it.