S1 Publishing(Oxford)© 1999-08

World of motorcycleS
S1 Publishing(Oxford)© 1999-08
Engine Rebuild
Kawasaki KX 250 (1991)
Starting with the crank
New big end roller bearings, new big end journal, con (necting) rod, and  new washers. fitted, aleigned by Jim Axford (Now retired)

making all internals are fittend and aligned before you place over the second crank case is essential, no point have to do it more than once unless you have to.
 I noticed the two o rings on the ley shaft (this lets me know it is a '91 made engine (only 1 o ring on the '90)
I put the nut back on the end of the shaft, placed a piece of wood over the end and hit the wood with a large hammer to aleign the crank the last 1 or 2 mm
Making sure the centre of the con rod is in line with the crack between casings. I had smeared a small amount of gasket goo adjoinig pieces as usual
 Then I torqued the case bolts. As my torque wrench never went click on it's lightest setting, I guessed 1kg/m would surfice. The crank still ran freely as did the gears, no threads got stripped, so I'm happy enough.

External gears gear
(I.E. not the garbox gears)
Crank shaft drives clutch so "primary" gear cog
(front right hand side of engine)
Then next the crank cog to drive the water impeller
Followed by the circlip to hold them both in position
The Kick start cog.
 The bar behind this hooks over a bar near the top, locate that then hook the spring into the shaft, insert the nylon spacer inside the loop of the spring, then thension the speing anti clockwise until the open of the sprin fits into the hole provided.

Gear selector system
Hook the lower hook over hole in the bar, and hook the top hook over the knub above
slide the gear shift shaft into the hole
hook the second spring into position
Followed by the 3rd spring

First place the smaller of the two thrust washer over the shaft
followed by the spacer
Then the roller bearing
Now the clutch basket
Then the larger of the two thrust washers
Then the core or crown of the clutch
Then the 3rd washer whis fits over the splines in the shaft
Then using the clutch splitting tool, and a torque rench, tightening the clutch nut
Then the clutch push rod goes through the hole into the centre.
the clutch rod cap and two washers
Then the clutch plates go back in, en the same order they came out.
and the clutch cap
finally place the springs and bolts into position, the smaller of the two washer fites into the midle on the spring and the larger fits over the top if the sring
 Before you tightn these make sure the bar on the other side of the engine where the clutch cable runs is in position.


Generator system
Place the stator plate into position
 Here I'm twisting the plate until.....
the marks I made before I removed the plate are in aleignment
Next I replace the woodruff key into the grooive in the crank shaft
Then aleign the rotor sot the groove fits over the key
 Then placing a piece of wood over the rotor and using a large hammerd the rotor into position.
I then held the crank still while I tightened the generator nut, again use two pieces of wood under the par to stop crank case damage

Making Paper Gaskets
First I made templates for the four paper gaskets I needed, then I cut out the middle
Then, using an unused dowel from an old engine, I cut  the holes for the bolts, just placing the dowels where the holes should be, then hitting with a hammer
The cut out the outside and trim if neccessary.
 I then replaced all the side covers.

Pistons, Barrels & head
First the new little end roller bearings go into the top of the con rod
Followed by the pison slideing the gudgeon pin (wrist pin)  through the piston and bearing, securing it with the circlips
Place the base Gasket into position on top ov the crack caseings, studs through the holes
Making the pistons are postion correctly where the ends meet the pin in the groove of piston
Place the base gasket into position then, gripping the rings into position with your fingers, slide the barrel over the piston
Then replace and tighten the four nuts at the four corners of the base of the barrels (not the 9 head nuts were left over threads to lessen chance tread damage & loss of nuts)
Replace the head gasket and head, torque down the head nuts. Replace gear leaver, gearr change lever etc then replace into frame.

©2008 - (updated & revised 2012)