Restore 1993 KX125

[bluestreak04]

Hello, I have not been on this site for many years now, glad to know that my login still works.

I recently picked up a 1993 KX125 from a close friend. Bike runs decent, it has brand new PC exhaust system, and a rad valve. Bike truly needs a complete restoration to be safe at speed. Spokes are loose, chain is bad, sprockets worn, brakes are terrible. I have been looking for a project like this for a while now.

What other year model 125 engines will "BOLT" into the frame? Considering this as it seems 1994+ parts are easier to come by. The last 1993 KX125 I had back around 2001 was not very reliable. I was only 15 then, so its also most likely my lack of experience that contributed to my problems. Young and dumb. I have done a Frankenstein build on a Honda CR250 before (2000 engine in 2002 frame), so I am looking for something a little "out of the box" on this bike also.

[umberto]

I found this thread from a guy in a similar situation.  Read the third post from Motopunk on the motors and cooling systems.

http://www.kxriders.com/forums/index.php?topic=11581.0

[bluestreak04]

Very interesting. The only reason I could see that the cooling system would need to be changed is because the 93 has two hose nipples vs a single nipple on the 1994+. I wonder if I could use a newer engine, and just run the older head?? Thank you for sharing that link.

[sandblaster]

93 to 02 use the same head gasket so you might be able to bolt on the older head to the newer engine.
Reliability is good on any of those years if a thorough rebuild is done.
Being cheap will only give you problems..

[bluestreak04]

I have read in a few places that the 1993 reliability is terrible, why exactly? When I did rip the bike down the field, it ripped, was faster than I expected, but it would lose spark after ripping hard. I have a complete ignition system for it sitting on a shelf until a final plan is settled on.

[reklessj]

I have read in a few places that the 1993 reliability is terrible, why exactly? When I did rip the bike down the field, it ripped, was faster than I expected, but it would lose spark after ripping hard. I have a complete ignition system for it sitting on a shelf until a final plan is settled on.
[/quote
1990  was the worst year for the kx125. Never had any issues with my 93

[bluestreak04]

good to know, thank you!

[DoldGuy]

I still have my 93 KX125, can't convince myself to let it go as it is the strongest KX of any year that I have ridden. Had the same issue with the ignition...was not the CDI or the Stator or the Coil, the resistor in the spark plug cap would open once the motor got warm & lose spark (new coil does not come with the cap). This bike has been VERY reliable with a few details covered, mainly the transfer ports need to be balanced (one side of the cylinders transfers are lower than the other). In my opinion, this is the cause of reported detonation on these motors, the uneven transfers cause a lean condition on one side, leading to the problem.

The 93 model uses a Flat Top Piston with a 16mm pin, if you get a different head you will need a 94 head as it is a flat top (piston 15 mm pin) later years are domed and would need the head cut to accommodate the different domes. Later year rods will fit your crank and offer greater piston selections, just get the proper length rod.

Hope this helps & looking forward to the restoration!

DoldGuy

[madmike]

hi Dold guy just wondering if you still use this and could help me

[DoldGuy]

hi Dold guy just wondering if you still use this and could help me

Will help however I can....