reasembling cases

[rpuchowicz]

I have a 94 KX 250 with a leaking crank seal. After reading all the threads about splitting cases I got them apart. I don't want to replace the main bearings because they are fine and I am not planning on keeping the bike for too much longer. The bearing are currently on the crank. My question is whether I can reinstall the crank into the cases while the bearings are already on it or do is have to remove the bearings, press them into the cases and then install the crank. If the bearings must be first removed from the crank is there a way of doing this without damaging the bearings. There is almost not room between the bearing and the counter weights to get the arms of any kind of puller to grab the bearing. Any suggestions?

 

[MXTex]

I think you can heat the cases and install right over the crank with bearing already on it.

 

[kxrider125]

If you have the cases apart and the crank out allready,spend the $20 and have all the bearings replaced.Any bearing supply shop will gladly match them up for you,and the seals.Do the guy you sell the bike to a favour and give him fresh bearings and seals.You may get more interested buyers if you can say that it was done.The bearing will come off the crank easily with a bearing puller,not the "finger" type the other one,im sorry i do not know what it is called,maybe some one else here can enlighten us.
Tony

 

[Mike R.]

I wouldnt go heating the cases

Ive seen quite a few reports of people doing it and then they warp them. Then walla you have cases that leak.
Aluminum warps easily with heat.
Just my 2 Cents

 

[SULLY]

you need the type of puller that is two plates with circular tapers that first sit under the bearing then pull together to pull off the bearing from the crank. Like KXrider125 I can't think of a name of it...maybe taper bearing puller?

 

[SULLY]

Found a link for the puller...it's called a bearing separator....
http://www.machinemart.co.uk/product.asp?p=040211225

 

[muddy226]

You should be able to re-assemble as is, put the crank with bearings on in the freezer for a few hours, heat the cases and everything should just go back OK. Something I have never done but a friend suggested is that when installing the stator side, he puts washers on the threaded end of crank and draws it in, to avoid any possibility of squashing the crank/deforming the crank pin.

 

[darringer]

Heat the cases to about 200*F.(Water sprinkled on them sizzles). It is not hot enough to warp them. I put them in a small toaster oven one at a time to heat them. Put the crank/bearings in the freezer for about 30 minutes to shrink them. Everything will slide back together easily. Sometimes I have to LIGHTLY tap the cases together with a small rubber mallet, but have never had any problems.