2013 KX250f piston question

I purchased the bike used with about 4.5 hrs on it from a friend that races and they raced the bike one time.

I had the bike and the piston cracked after about 8 hrs on it, I believe they used a different piston in the bike when they raced it so this piston was newer and not raced ? but I did not ask them to be sure.

Anyway the stock piston cracked and my friend said he would put a new piston in it if I paid for the parts and he had a JE high compression piston laying around that they used for one national race and we installed that piston.

I lost power with this piston, were I ride I use to be able to shift into third gear and the front would come off the ground and now I have to pull up on the bars for the front to lift in this certain section.

 no other mods were done to the bike after putting in this piston.

my question is:

what should I do to get my power back ?

If I install a stock piston can I trust the stock piston to not crack ? I have heard others having trouble with the stock 13 pistons.

any tips or suggestions to get me my power back would be great to hear.

 

I then needed a spark arrest for trail riding and purchased a PC 5T slip on muffler and I have lost even more power so any suggestions for this ?

Edited by predatorbass

I would replace the piston with a Wiseco standard compression piston.

 

If you had a standard exhaust and replaced with spark arrested pipe you will lose power as its more restrictive.

I would replace the piston with a Wiseco standard compression piston.

 

If you had a standard exhaust and replaced with spark arrested pipe you will lose power as its more restrictive.

Wiseco pistons are my choice as well. Pull the jug off before you pop the new piston in. Get some green scotch brite, soak with WD-40 and scrub the cylinder. Scrub up and down at a 45 degree angle in both directions 3 or 4 times around each way then wash with dish soap and warm water to get the WD-40 and grime off. Then coat the inside with motor oil immediately. The cylinder will look new with a fine cross- hatch pattern of micro scratches. This will help your new rings seat.

You may have lost power with the high comp piston if the rings didn't seat or if it needed race fuel to perform properly? Not sure about the last one cause I don't run high comp pistons.

Thanks Guys, my friend said it did not need race gas.

What kind of compression should I have ?

I am going to get a compression tester.

Thanks Guys, my friend said it did not need race gas.

What kind of compression should I have ?

I am going to get a compression tester.

 

62-103 PSI with 5 kicks WOT on a warm engine.  Make sure to get the adapter that fits your plug.  

What size adaptor do I need ? I purchased a motorcycle kit and it comes with three adaptors. M14x1.25,M12x1.25 and M10x1.0.

What size adaptor do I need ? I purchased a motorcycle kit and it comes with three adaptors. M14x1.25,M12x1.25 and M10x1.0.

Good the M10 x 1.0 is what you need. Hopefully you can fit what you have in there. It's tight as you know.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now