need advice for tuning my 1992 kx250

[kx92nateee]

my kx250 seems like it should have more power. it always seems to bog down a little and sounds scratchy. i just put in a new wiseco prolight top end. but havent replaced the reeds. could it be the reeds or is it just a tuning problem?

[KXcam22]

Nateee,
  The first things to check are:
1. Is the powervalve working properly.  If you put in a piston I am assuming that you have cleaned the powervalve.  After that it just making sure the linkage is working and the engine governor is working.
2. Is the compression within spec.
3. Clean the carb and check what jetting you have.  It might still be stock.

Is this bike new to you?   Hope this helps and welcome to the site. Cam.

[kx92nateee]

ok i have the cylender off  i can see the main valve and the two subvalves from top view and ther clean.from looking in the exhaust flange it looks to just be carboned up and dirty i had them all apart wen i did the new top end and cleaned. im thinking its my jetting or my mix. im mixing 40:1 and i used to run 30:1 i kept the same jets in. so its most likely the jets not being lean enough. have any good sites were i could get jets? thanks

[kx92nateee]

oh and wat size jets do u think i should use for running 30:1

[Hillclimb#42]

168 main, clip at 3rd, 60 pilot, 1 1/2 on the air screw. Thats stock settings. I would guess that as long as you star there and adjust clip and/or air screw it will be very close. Check the jetting chart on the search. 40:1 if you use synthetic two-stroke is fine.