Rebuilt 2006 KX450f piston is very tight

When I kick the bike over the piston feels way to tight in the jug. I dont know if I should try starting it like this if it will cause damage or not. Its a new wiseco piston with a new jug.

Did you Mic the piston to see how big it was.You have to check clearances on cylinder and piton.

I didnt I dont have a mic here thats big enough.

Did you check end gap on the rings?

I thought Wiseco only make two sized (bore) pistons. Std and oversized. So you check the part number. With a std piston and a healthy nikasil bore, then it has to be some other problem like the rings.

Typically, ring end-gap has to be modified (filed) to make factory spec. If you put the rings in right out of the box, they are probably binding cause of not enough end-gap.

Maybe not the rings. Did you torque down the cam caps to the right spec? If they are too tight it will give you a Binding feel when you kick it

I did tourqe everything to spec and the piston I bought from a local machine shop that worked on the jug for me.

you're going to have to pull it and check the end gap. I would almost guarantee that will be your problem if you didn't check it before assembly. Did the bottom end rotate freely before you installed the piston?

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