KDX 250 help please...

[THill]

I have owned and worked on a bunch of the later model ( 98 and up ) 200 & 220 KDX bikes but this is my first 250 KDX and I have a couple questions.
 It is a 94 model...   First removing the cylinder, The nut that holds the arm on that works the power valves , is it left hand threads like the 200/220 KDX  ?
2nd is the piston, would the letter  B  stamped on the top of the piston have any special meaning ? just wondering if has a standard bore or not.....

Thanks for any info.....

I will try and get a couple pic's of my Hybird up soon 03 KX / 02 KDX 220

[dave916]

The nut that hold arm of the powervalve should be standard thread/anticlock to open
Standard bore could have three slightly differant size piston A B OR  C , if the bore is good and does not need plating just stick a another B piston in it 

[THill]

Thanks Dave !!

[THill]

FINALLY got the cylinder off , it put up a good fight, almost a hour but it finally gave up ..Almost 40 years working on & off with 2 strokes i never have had one this hard to remove, this sucker was stuck on....But after removing it i found what i thought i would , the cylinder chrome was worn thin in a couple spots and a lot of piston movement in the cylinder explains it rattling a bit..All the passages were gummed up pretty good too , from what the guy said that i bought it from, he had it for almost 14 years and his buddy owned it new and he didn't think the top end had ever been off ,atleast not by him , so not to bad for a 20 year old bike..SO a rechrome cylinder and new piston along with a few other bits and are coming soon to see if I can get this ole 250 back running like it should...

[sandblaster]

You should consider putting a feeler gauge between the connecting rod and crank half to see what they play on your crank is.
I'd also seriously consider new bearings and seals throughout....
But I hate pulling my motor apart