Piston skirt broke

[samandson]

My engine seized in fifth gear w.o.t.!The skirt has broken off the exhaust side. It looks like time to bore a little of the stock size steel sleeve. My question is there a best size to go with? Forgot to mention that it is a 98 kx 250.

[KXDINO]

The best size is up to the guy who will rebore it , minimal size to clean it up , but you need to work out why it seized , most likely to small a main jet while it was w.o.t. in top gear , another thing is to replace top ends more often especially if there worked hard.

[68Fastback]

Ditto above, the bore size of the new piston will be determined by the machine shop and how much of the cylinder they need to remove.

[samandson]

Thanks for the information. I had a158 main jet in. The guy at the machine shop said to send a piston with the jug.Can a forged piston be used in a sleeve?

[KXDINO]

Go wossner on the piston if they make one for it , i say they would , 158 main jet is std size if your doing heavy sand work or holding it nailed on fire roads , go up a couple of sizes , you might help to gear it up a bit may be.

[samandson]

After doing some research definitely going to Wossner. I'm running 12/49 sprockets riding in Eastern Ky. hills. I'll order a couple of jets along with everything else.Thanks

[Heniz]

I highly rate the JD jetting kit. my 97 kx250 runs so nice with it fitted now even just on there baseline settings. 

The needle has improved responsiveness dramaticly

[samandson]

Hey Heniz,did you change all the jets? I just got three larger main jets to try get rid lean on w.o.t. What size neddle do you like?

[Heniz]

the JD jet kit comes with 2 needles a blue and a red one. Blue needle 3rd clip, 45 pilot 170 main