97 kx 250

[kx250andrew]

irecently purchased a 97 kx 250. the engine is all stock with a delta force 2 reed setup, a procurcuitplatinum pipe and spark arrester.the suspension was done by factory connection.the question i have is concerning the powerband. it has a very strong mid range with decent low but it feels very weak on top. i was told that changing to the pro curcuit 304 silencer will give me more top end? also I will be replacing the top end shortly. I am a machinist an am wondering if there are any mods i should make to the cylinder or the head while it is apart. I am not looking to shift the powerband to the top i just want it to feel a little stronger up there without sacrificing the low and mid. Thanks for your input
Andrew

 

[EricGorr]

You may find that the powervalve (center) is carbon blocked and won't open fully. So cleaning the KIPS system is most important. For the porting, use a die grinder and an oval shaped burr to raise the exhaust port to 38mm from the top of the cylinder. Be carefull to polish the port edges and especially deburr the junction between the exhaust port's timing edge (top) and the center valve cavity.
Also check the edges of the moving wedge valve for burrs. Theres a good picture in my book. When the edges get burrs, the valve won't open correctly.
Good luck

 

[OKKX'er]

Like Eric said, you must have a powervalve not opening. Before '97 KX's didn't
have any rev, but a '97 will pull well into the upper rpm's.

 

[Senior KX Rider]

My 97 was no top-end screamer but it did pull pretty strong into the upper rpms. I would check the powervalve and maybe take a look at the jetting.