1990 kx250 h1 exhaust

[pb50nmineralspirits]

 
     was wondering what exhaust will work with my 90 kx250 build?? or should i try to decarbonize the stock pipe?? thanks for any info.

 
      pb50nmineralspirits

[RonnieMac]

Pretty much your only choice is Pro Circuit factory sound.  As for pipes you have a few to choose from.  I'm doing a 91 build myself.

[pb50nmineralspirits]

yeah its been an adventure for sure, thank god for ebay.. thanks for the input.. i have acquired a handful of dirtbike tools now too.. all new engine/transmission seals, bearings, gaskets, used transmission, was a horrible project lol, idk if they sunk it in a river or lake or what and let it sit for some years but i got for next to nothing and have 600 in it i figure a few more hundred and it will be done (including shop service for rebuilding/balancing/trueing crank) things i have no equipment or desire to do.. they sure beat it up, but im sure gonna fix it n do the same



see the ¾" thick crap in the bottom of the case lol



the piston is a wiseco, was ok, measured clearances, checked out so i cleaned it up, had to torch the rings off no biggy..







pretty much building from the ground up.. :/

[pb50nmineralspirits]

heres a better picture.. yeah i had to replace a lot of internals.. owell.. in my opinion, this bike is the ultimate resurrection.. also my opinion, if you dont know what you're doing, let the shop do it.. i did almost all the work and if you dont have the special tools just dont even try, do more harm than good.. still need to clean up most of the top end and replace all vent tubes and hoses.. i read a lot of info about the cylinder heads too, and literally NO ONE is talking about the wearing/thinning of the NikaSil coating and when to replace/re-coat them??? i guess, if the cross hatching is still in there (which mine is), no ridges you can catch a fingernail on, no huge noticeable chipping or flaking or thin spots, no major scoring, or minor for that matter, you're good.. just have to deglaze it with soap/water scotchbrite, or some sort of petroleum disillates.. and there is a technique so u dont mess up the cross hatch pattern.. oh n of course the measurements have to spec up.. clearances n whatnot.. have no clue and cant find out when to replace connecting rod.. no idea how to check for tolerances, stresses, or bent.. hot rod rod so idk..

[Rocco H.]

Hi. My name is Rocco. I'm new to the forum. I am rebuilding a 90 kx250 too. What I did was aI bought a 1991 Kx250 pro curcuit exhaust and modified the top bracket and it fits.