BORING Questing

[kx100]

Does anyone know if a '01 KX 100 is boreable with the stock piston?
Or does it need a sleeve or a whole new piston made out of CI?
I would like to bore it out to a 120cc.

any input would be greatly appreciated!

 

[spanky250]

The KX 100 (or any other modern bike engine) is not boreable as far as a rebuild is concerned, but maybe someone makes a big-bore kit for it. Try clicking on that Eric Gorr button over on the left.

 

[EricGorr]

Kaw uses an Electrofusion plasma coating of tungsten and iron applied directly to the aluminum cylinder. You can't bore it in a traditional sense.
In order to bump the displacement up to 121cc (the max) the cylinder will have to be bored and plated to 54.5mm and the cranshaft stroked 2.5mm.
RPM offers this service and it costs about $1,800 once you buy all the extra gaskets and bearings needed to rebuild the bottom end.
Me and obe of my friends in Texas who builds strokers like this, built one to track the costs of operation of an engine built one the edge like this. When you stretch the limits of any engine design reliability is going to suffer. Figure on rebuilding the bottom end more frequently with a big displacement mini.
For what you'd spend hopping up a mini you could buy a 5 year old 125!
Good luck, Eric