KDXRIDER.NET

Hi guys,

i need some help again.. I got a KDX 250 that im trying to fix up and thought i would do the top end..
So i pulled it all apart and wanted to get replacement piston and rings, i googled the number under the piston that was 4sr00 and found that it was a yz 250 piston and rings.
I want to know if you think i should put the KDX 250 piston and rings in or just got the same replacement part?
As far as can tell the dimensions of the pistons seem to be the same as the KDX.. i checked the bor and found it was about 67.50. so i don't think they done anything big to make the yz 250 fit..
I just want to know what you guys think and maybe tell me the difference in the pistons of a 2 stroke bike?
When i asked the guy that i bought the bike from he said he never done the top end on the bike... so i thought it was about time to do the top end..

Please let me know anything that you guys think or if you need any more info from my side.. all the help will be greatly appreciated

Thanks

you will need to identify the year of the bike and check what was stock, then measure and confirm, 67.4 mm is stock `91-`94 this link may help some

http://www.procycle.us/wiseco/wisecokaw175-500.htm
http://www.lukesracing.com/luksr/WPKD.htm


cheers

ian

I'd stick with what's in there as its been honed to match that

Hi Guys,

i want to post some pics of the piston and barrel. the barrel and piston are smooth and i don't feel any notches or scratches in them.
I also want to find out if the dark marks on the piston could be the rings from blow-by or warn rings?



















So what you guys think?

im not very impressed by the whole setup
there looks to be some heavy wear on the piston, aswell as the bore

a new piston will definitely seal up better and make more power then what is in there now
I would not order one from a different bike because even though the bore and stroke may be the same there are different things to consider, like the location of the wrist pin for instance
if you move the wrist pin down by about a mm you might raise the piston enough to send the spark plug through it the first time you kick it over
(on a side note, it looks like the piston from a 1990 KX 250 is identical to the 90-94 KDX250 unit)

another thing to consider is porting, who is to say the skirts of the YZ piston would properly time the ports on the KDX barrel ?
come to think of it, that might explain the hackjob done to the ports on your barrel, it looks like it was chamfered by jack the ripper


I wonder if the bike ever had any cooling issues with all that goop on the head ?
definitely something i'd want to address if I were you, and see where else this stuff is (over)used

I say cylinder needs a replate, as well as a new piston and rings, etc.

+1 on replate and piston kit then you can buy the kdx kit instead of the yz kit this time too.

Hi guys,

thanks for all the replys.. What i have done is found a wiseco distributor in south Africa that should be able to get me a better price on the KDX 250 piston kit for me.
Kawasaki here can be a bit expensive sometimes.. But now just looking for somewhere to replate it now..

seriously, am I the only one who is worried by that port job ?

and it almost looks like there are some cracks in it aswell, no ?

I think i will take a closer look at that tonight. and let you know what i find.