90 KX250 rebuild

[SOHC]

After a few emails I got a good clutch arm witch wasn't rusty.

And some sand blasting and cleaning of parts


 

[SOHC]

got a swing arm bearing kit, all the other bearings are Pivot Works but this is a made in Taiwan kit

[SOHC]

Sandblaster has got me a clutch basket witch is on its way from the US to me now, still need some clutch plates and some gaskets as the 2 gasket kits I got don't have every gasket for some reason.


I will get the rod kit pressed in at some stage, I use to do it my self in my younger days when I had full rain on a motorcycle shops workshop. I can put the cases together soon, I hope nothing binds up.

     

[SOHC]

Got my repaired and replated cylinder back, they did a good job apart from I spotted one flake of chrome in one of the ports that I had to remove as it was going to brake off and cause trobble.




 

they recommend 5 mins running at idol then 25% more for another 5 mins, then 30 mins at light throttle, then cool down and re torque the head then give it another 30 mins light throttle.

My crank is getting pressed as we speak to.     

[LukeG]

Looking forward to seeing the results.

[SOHC]

put most of my motor togeather only to find it didn't change past 3rd because I put a 4th gear from a 1992 witch needs to mate with 4 drive dogs not 3  got a NOS one on the way now.


I rebuilt my brake calipers as they were jammed, the rear piston was all broken on the end so I machined it back in the lathe, its a bit shorter but its nice now.

Also I got rid of the small o ring seals in the top of the bore, they are the reason the pistons seize, and I have changed to DOT 4 brake fluid.       

[sandblaster]

Also I got rid of the small o ring seals in the top of the bore, they are the reason the pistons seize, and I have changed to DOT 4 brake fluid.        

What I have found is that dirt get's pushed past the first dust seal and eventually becomes plugged up between the main seal and dust seal.
It creates a mud like concoction that can completely freeze up the piston.
Once disassembled and cleaned the piston should push in easily with your finger.
By removing the outer dust seal you should find that your brake performance will deteriorate much faster as dirt pushes past the main seal and contaminates the fluid.
If I were you I would get another outer seal... But then I really like to stop when I hit the brakes  

[SOHC]

I will give it a go with out those first seals, they were all shredded up and bits were poking out, I don't ride in dirt or mud so should be ok.

Both master cylinders have failed now, I think someone had put a mixture of DOT 4 and 5 in there     

[SOHC]

Got my new gear in the post today, and I got the wrong one, I wanted 4th but got top as is had a part number witch looked the same.

[SOHC]

I ordered a 2nd hand 3rd gear to replace my damaged one and now I have the cases back together and the cylinder back on, I did a dummy assembly of the 1996 waterpump parts, they fit straight in, I just need to shorten the shaft a couple mm where the impeller bolts on.


This would be a good mod for anyone else who has a cracked or broken water pump drive in there 1990, PS you carn't use the later impeller, it doesn't sute the housing.   



I got my swing arm repaired and that is all bolted into the frame with the motor, photos to come.

[SOHC]

I had my swing arm drilled and a steel insert screwed into the damaged hole someone had failed at drilling and tapping 3 times, and a hellicoil put in the other side.

[SOHC]

Also fitted the swing arm and links, there is zero play now, it had about 30mm before, installed the motor, need to make new front engine mounts and weld a bracket to the frame for the exhaust.


 

[SOHC]

Rebuilt both front and rear master cylinders, the rear one the cerclip was very rusty and broke into 3 parts, I have no brake fluid to test them.

I just need to find a clutch plate kit, I welded all my steel plates together to make a tool to hold the clutch hub.

Need a intake boot rubber thing.

chain and sprockets.

Air filter.

Weld on exhaust bracket and fix both flat tiers. then fun times begins, hopeful fun in riding and not finding why it won't go     
     

[ecdeyzel]

Looks good SOHC! That motor looks like you can eat off it. Cant wait to see the complete bike. 

[SOHC]

Thank you, the whole engine has been beed blasted and wire brushed, I hope it will stay like that for a wile.


I made a new bronze bush for the kick start idol gear and was about to put the clutch side of the motor together but found the primary drive gear on the clutch basket was very worn, I am now in the process of changing that gear witch is held on by a aluminum plate witch is riveted on.