90 KX250 rebuild

[SOHC]

I thought I would start this topic so I am not posting silly questions all over the place and you can see what I am dealing with.

Anyway I got this 1990 250 that was in bad shape the guy sed it was all there with the new parts and it just needed putting together witch was a lie, the new parts didn't fit as they were for a jet ski, the motor had sucked in lots of water and sand and the new piston kit looked like it had 4000 hours on it, all the bearings in the motor gearbox were rusted and warn out, I had to replace 2 and 3rd gear and the out put shaft, radiators were bent and crushed, expatiation chamber and exhaust were bent, rusty and crushed, all suspension bearings were rusty and the lower shock bearings had long since warn through the bearing into the link it self, front forks had corroded so badly they might snap. I lost alot of the before photos but I have a couple.

I will post up the pictures of my work 

[SOHC]

This is the photos the seller took of it in his shed and before I washed and sanded it.

[SOHC]

This is the best I could get the expansion chamber. I hope to find another one one day.



I gas welded a peace of aluminum CB antenna mast I bent to make a new tail pipe, I don't have a TIG welder and its hard as hell to gas weld aluminum, I also replaced the exhaust pipe inbtween the muffler and expansion chamber as someone had used brazing rods and silver solder to try and repair rust and cracks



I had the link welded up and re bored as it must have worn though the bearing into the link at some stage and someone had bored it right out and hammered in a different bearing and packed it out with washers, yuck.

 

Swing arm needs the wheel adjusters welded up and re drilled and tapped as both threads are bad as some monkey had tried to re drill one and messed it up

[SOHC]

I tried to fix my old radiators but after I twisted one straight I think I cracked it, but I saw thees China radiators witch were very cheep and they don't look half bad so I grabbed a set witch was lucky as it was the last set he had, and anything is better than my old ones.

 

[SOHC]

This is where I got stuck and ran into trouble, my front forks were corroded to the point they may snap, I got a pair of 1992 forks but they didn't fit my 1990 axle or yokes. So I got a pair of 1997 yokes witch then didn't fit my bearings in the steering head so I pressed out the steel spindle in the bottom yoke from a pair of 1992 KDX250 yokes witch is the same as my 1990 spindle and sweated that into the 1997 bottom yoke, I also had to use a KDX top yoke is it takes the bigger forks but still had the same spindle bore as the 1990.

Now if all goes to plan I just need to make 2 sleeves to put over the ends of the front axle and easyflow them on so they can fit the bigger axle clamp.

I didn't paint the frame, I did polish the fork legs. 

   

[SOHC]

Had to have some welding done on the inner clutch cover and on the engine case where the clutch cable mounts as it was broken off, then I beet blasted the engine cases and fitted all new bearings, seals etc,



I had to find a new crankshaft as someone had put in KDX250 flywheels witch were junk anyway, I now have a proper crank but it needs a new rod kit.



Thats about it for now, my cylinder is off being replated and I am looking for that clutch leaver that goes into the case. I would say alot of the damage on this bike was done form water blasting and steam cleaning.   

[ecdeyzel]

Awesome build so-far, SOHC. The forks mission sounded like a royal pain in the @$$. Love to see the progress.

Ed

[LukeG]

I ended up getting forks from the UK, there must have been something dodgy going on with the gold forks in 1990 because mine were corroded and cracking apart like yours. I am curious how the chinese radiators fit up as I am yet to buy any for mine. Keep up the good work and the updates as I know I haven't updated my build thread in ages.

[SOHC]

The radiators did need tweaking as the mounts for the guards and the mounts to the frame were off, I can see where one pin hole in a weld has been penned over at the factory.


I think with the forks its the anodizing when it gets a chip water can get under it and get trapped and it fizzes away, I polished it all off some blue forks and I will just hit them with the silicon spray, they did have a couple spots that I had to grind out.

I saw a Yamaha yz 250 that had the most rotten forks ever, they had swelled up to about 25% more of there orinagle size.       

[LukeG]

My forks were nearly that bad. The aluminium has swollen and flaked like cast iron does. I'll post a picture tomorrow to show you.

[sandblaster]

I have seen many of the earlier USD forks with the flaking.
I just parted out a 1990 and the Uppers are nice.
But, they are silver, not gold.
Must be a USA thing.

[SOHC]

Must be a US market thing with the silver forks.

You don't happen to have the clutch leaver at the gearbox end and a clutch basket would you from the 90 you parted out Sandblaster?

[LukeG]

Here's one of my fork legs.



I bought a new Mitaka clutch basket off ebay.

[sandblaster]

You don't happen to have the clutch leaver at the gearbox end and a clutch basket would you from the 90 you parted out Sandblaster?

I don't know what all I have just yet.
Here's a link to what all I have for it right now
There is some more stuff but I'm working on it.

http://stores.ebay.com/OEM-CYCLE/_i.html?_nkw=kx250+1990&submit=Search&_sid=680025

[SOHC]

That fork leg looks like my old one LukeG , watch out it may go very deep into the leg itself, I will look into one of those new clutch baskets, might save a lot of work as I was going to weld up my old one.

 
I try to get stuff from ebay but a lot of the sellers won't ship to Newzealand