bottom end rebuild on 98 rm250???

[dirtride321]

First off just wanted to say what's up to everybody, this is my first post here :cool:

Recently i just picked up a 98rm250, it was to good a deal to pass up. Catch is the bottom ends needs a rebuild, and I would like to do it myself. I've never really worked on 2strokes but have done a lot of work on cars so i'm pretty mechanically inclined. Aside from a new piston, pin, rings, and gaskets is there anything else i need? Also any tips on honing the cylinder and how to go about disassembly and assembly would be great. Finally anybody recommend where i can get a kit or specifically what brand to go with? I also saw coated pistons too, do these help out in 2 strokes or is it just a gimic? Thanks in advance for any help guys.

 

[wornknobby]

well for one welcome to the club :cool:
the most affective way to hone the cylinder is to use a ball hone. some people use stone hones, but they don't work as well. the ball hone is a great tool.
as far as brands wiseco makes some pretty good pistons. the coated pistons i have never delt with and havn't had any problems with wiseco.
i only go with wiseco b/c they have complete kits that are cheaper than others. :)
go towww.midwestactioncycle.com] www.midwestactioncycle.com[/URL]
they have complete top-end rebuild kits for your bike for $109.
they also have complete crankshafts and crank rebuild kits for your bike. :aj: :aj:

 

[Rcannon]

The weisco piston is great in the 98 RM 250. I am working on one for a friend. It also needs bottom end work before thsi season ends.

Please post back and let me know how the job went for you.

If I choose not to rip into this one, a local shop offered to do the lower end work for 300.00.

 

[kawrider]

Botom end rebuild

Hey!
Good luck on the rebuild. The first thing you will need without question is a factory service, repair manual. I rebuilt the bottom end of a 90 KDX about six years ago and the manual is worth its weight in gold. I don't know if I will ever attempt to do another one, My nerves are too bad now!
You are probably going to need some special tools to seperate the cases. I tried several different pullers and none worked right. I carried the case to the dealer and he popped them apart in about 2 seconds. He had a plate with holes drilled to match the KDX case. He had others to match kx's rm's etc. This plate is called a "jig." Then, you install the case screws and pull the cases apart just like a gear puller.
This is one tool that is invaluable and almost a must.
You are going to need a heavy press...I think the one I used was a 20 ton and still had to lean into it when we pressed the rod pin out and then re-installed the new one.
The critical part is trueing the crank throws...and keeping it that way while you press the halves together.
I'm not trying to scare you, I just want to let you know what to expect. If you don't have a well equiped shop, {or a friend with one} expect a couple of trips to the dealer. Having a friend who has done a couple of bottom end rebuilds is a plus also. I hope this helps and I hope you suceed! The 'DX I built is still running strong.

Dave