KX Riders

Maintenance & Technical => KX250 / KX125 => Topic started by: samandson on February 25, 2017, 02:49:18 AM

Title: Piston skirt broke
Post by: samandson on February 25, 2017, 02:49:18 AM

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.

Title: Re: Piston skirt broke
Post by: KXDINO on February 25, 2017, 11:11:00 AM

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.

Title: Re: Piston skirt broke
Post by: 68Fastback on February 25, 2017, 12:13:44 PM

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.

Title: Re: Piston skirt broke
Post by: samandson on February 26, 2017, 12:58:48 AM

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?

Title: Re: Piston skirt broke
Post by: KXDINO on February 26, 2017, 07:08:53 AM

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.

Title: Re: Piston skirt broke
Post by: samandson on February 26, 2017, 08:55:42 AM

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

Title: Re: Piston skirt broke
Post by: Heniz on March 09, 2017, 11:29:32 AM

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

The needle has improved responsiveness dramaticly

Title: Re: Piston skirt broke
Post by: samandson on March 10, 2017, 01:45:17 PM

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?

Title: Re: Piston skirt broke
Post by: Heniz on March 11, 2017, 12:18:40 AM

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