There is no slop or play up and down on either the wrist pin or the connecting rod. There is some side to side play on both the wrist pin/piston and connecting rod, but the head and jug are off so that would allow some side to side play I would think.

Now I'm at a total lose. It sounded like a wrist pin or connecting rod knock. Once it started making the knocking noise it never got worse and never lost any power. It just made noise. What else could make the same noise as a bad wrist pin or connecting rod? What do I look at now? I want to get this fixed so my son can ride it.

I'll take all the info I can get!

Thanks, NYH1.

 

While it's apart, you could check the piston to wall clearance.
It sounds like it could be piston slap.
Get into the clutchs to maintenance them and make sure all is well in there.
Then I'd assemble it and run it...

 

If it is piston slap what do I look for to see if that's the problem and how do I fix it? Do I bore and hone the cylinder and get a new piston and rings? I want to fix this and get rid of the noise.

Thanks, NYH1!

 

Measure the piston and the cylinder and make sure the clearance is within spec. If you don't have a dial bore gage you could have a local machine shop measure it for you

 

How much clearance should there be between the piston and the cylinder? Is measuring these pistons like measuring them for a car/race engine, opposite of the wrist pin down by the skirt?

 

I consider .006-.008 acceptable but getting close to max.
A new piston (stock or pro-x) is set at .0025 clearance. A Wiseco at .003-.0035

 

I looked at the cylinder bore better today. There are lines going up and down in the front and rear of the cylinder wall. They're visible but I can't feel them with my finger nail. Both sides of the cylinder I can see the cross hatch on the cylinder wall. Would this be an indication I have piston slap?

NYH1!

 

Anyone??

 

No.
You need to have it measured or just get a new piston and bore and then you know it's 100%.
Looked into the clutchs yet?
Maybe tighten the front motor mount bolt, that makes a horrible sound at times when loose.
Chain spinning on the front sprocket (wore out sprocket)?

 

I'm taking the jug to a shop to have them measure the bore. I haven't looked at the clutches, all I took off was the head and jug. What's involved in looking at the clutches? I haven't taken the case apart, trying to avoid doing this if I can. The motor mount bolts were all tight when I took them off to take the motor out. It made the noise at idle while not moving (not as loud as when riding) so I don't think it's the chain or sprockets. Like I said, it never lost any power at all, just made noise.

I don't have a shop manual yet so I don't want to tear into it to much until I get one.