I have installed 2 different bore kits for my '05 Zuma and they keep blowing up. WHY?

Question

This kit is pretty simple, comes with new everything, just change it out, well i did that and they seized. the piston had huge scrathes in it.

Answer 1

If you have increased the displacement of the engine and are still using the stock oil injection pump, you might not have enough oil getting to the engine. Just adding some two stroke oil to the gas will help a great deal.

Also, if you still have restrictions on a stock exhaust and carburetor, loose them. You may find that you will have to increase the jet size in the carburetor to feed the bigger cylinder properly. Not enough fuel will cause the engine to run lean and heat up the piston and cylinder. An aftermarket exhaust with an expansion chamber is also a great help to get the exhaust out faster.
Ride Safe

Answer 2

Do you have oil, in the oil tank?
Are you using Yama-lube for injector type engines?
Don't use chain saw, or boat motor 2 stroke oil.
Did you check the piston to cylinder clearance?
Did you check the "ring end gap" before putting everything together?
You'll need a manual for the specs.
http://www.motocom.com/motorcycles/
Is the oil pump working?
Did you bleed the oil line?
Remove the spark plug.
Remove the oil line from the carb.
Crank the engine over (with the starter motor).
Let the oil drain into a cup (so you don't make a mess).
If no oil comes out , figure out why.
Keep cranking until there are no air bubbles coming out.
Then re-attach to carb.