2001 KX250 Engine Rebuild

[Swimr2DaResQ]

My KX finally died, I am looking into doing a full rebuild of the motor!
Wiseco will probably be my first choice for the piston and rings, a Hot Rod crank, and possibly some Micro Blue bearings if they make them for my bike! I am going to get it ported and polished and if the funds allow get my suspension Tuned and rebuilt!
If anyone has any suggestions on better parts or services, I would appreciate it!   

[Swimr2DaResQ]

Has anybody used or have any info on Namura Technologies pistons and gaskets?

[Charles Owens]

I would stay away from the Namura. Go with a good quality piston.
OEM or Athena if you want to go cast, Wiseco for a forged.
Good luck on the build, post some pics!

[Swimr2DaResQ]

Are they a new company? Never even heard of them til a few days ago!

[MyckMcClung]

They're really huge in Europe,
I'd save the money from all that porting and polishing crap, invest in a Vforce2, or 3, repack your silencer, and get an expansion chamber that suits the need of your riding style.FMF make four different pipes for your bike that range from lowend  enhancements to high end enhancements, the Fatty is the overall performance enhancer, Then put all that money you're gonna waste on that motor work into your suspension. A worn out motor doesn't make as much power as a fresh one, just rebuilding the lower and upper ends will bring that bike back to life and will be alot more powerfull than you are thinking it will be.

[scotty dog]

MyckMcClung is on the money, dont waste money with portin n poliishin, get ya suspension done first, and ive heard from more than one person on here to stay away from the Hot Rod cranks....

[snook620]

My project yz125 motor is sitting on my work bench right now with a locked up Hot Rod crank. Although I cant say for sure what the previous owner did to destroy it.

[juliend]

I would stay away from the Namura. Go with a good quality piston.
OEM or Athena if you want to go cast, Wiseco for a forged.
Good luck on the build, post some pics!

Interesting. Can you elaborate? I've always been pretty impressed with Namura pistons. I know they aren't very big over here in the US, but I've installed a few, and they seem very high quality.

If you're beefing it up a bit, I would def go with a forged piston. You can't go wrong with Wiseco, for sure. Who's doing the work to the cylinder?

[snook620]

I've considered buying a Namura piston because of the cheap price but always ended up with a wiseco. I've never had a problem with a wiseco

[Coop]

I have heard Namura are pretty popular in Europe, but never spoke to anyone one on one to verify this. It's just something I read and you know what they say about that...

[dogger315]

The 2001 KX250 responds very well to porting, cylinder head modification and
a Wiseco super light flat top piston (#704PS).  This piston was developed and
used by Team Kawasaki and allows the bike to rev faster.  The stock ports are
small and the port timing causes the engine to fall flat early.  The head work is
required for the flat top piston.  These mods really wakes up the engine across
the power band.  The bike already has a nice Keihin PWK Air Striker carburetor. 
Bolt on a Rad Valve and Pro Circuit pipe and silencer to complete a very stout
package. 

dogger

[2T Institute]

Pipe is the cause of signing off early not the port.Polishing ports went out in the 70's. Flat top piston is a good idea.

[dogger315]

Pipe is the cause of signing off early not the port

No, the exhaust ports and the intake boost ports were reduced
in size from the 2000 KX250 causing the motor to fall flat in
comparison.

Polishing ports went out in the 70's

Nobody but you is talking about "polishing" ports.  The exhaust, sub
exhaust and transfer ports all need to be enlarged and/or reshaped
to wake this engine up.

The '01 KX250 engine had a mid only powerband.  It was less than
impressive and in need of serious work to bring it up to the level of
the Honda and Yamaha of that year.  Bolting on an aftermarket
pipe and reed alone isn't going to do it.

dogger

[MyckMcClung]

on the Hot Rod tip..... I've used them in the last two crank rebuilds i've done, the first was five years ago, over 100 hours, 3rd piston, not even a notion of any wear.
Just installed the second, I'll let you know how that goes.
I've found that most guys that bash aftermarket parts cause it failed on them, usually have a half waffle grip on the left bar, that is an inch from the end and the waffle is in their palm.

[TotalNZ]

on the Hot Rod tip..... I've used them in the last two crank rebuilds i've done, the first was five years ago, over 100 hours, 3rd piston, not even a notion of any wear.
Just installed the second, I'll let you know how that goes.
I've found that most guys that bash aftermarket parts cause it failed on them, usually have a half waffle grip on the left bar, that is an inch from the end and the waffle is in their palm.

LOL, gold