Hi guys, i've been rebuilding a 1998 kx250 that was used and abused. The cylinder was scratched and the piston was toast, so I sent the cylinder away to get nikasil'ed. I just got it back and it looks fresh and perfect. There was play in the rod/crank bearing so I bought myself a new bottom end, and finished it off with a new wiseco piston/bearing/wristpin.

The reason I split the cases was one of the output shaft seals leaked and sucked in some dirt, which wrecked that bearing. (it still spins but feels gritty). I ordered up a new bearing/seal and also new crank bearings and seals. Are there any other bearings in the engine that I should replace while I'm at it? I guess I am being a little paranoid because I spent a lot of money for practically all new internals, and I don't want some stupid little bearing failing on me and wrecking the whole engine. (could that happen?)

Anyways, I am just looking for opinions. All the other bearings spin smoothly and the seals look good.

twowheeled said:

for another $60-80, you can replace every bearing in the tranny, which i highly recomend, especially with the way you desribed the bike

I had the same problem man. I had a major piston failure and my engine was just hammered. I replaced the main bearings for the crank and the other smaller ones. I got to thinking about it. The bearings that were not harmed still moved fine but I did not want to chance it and splitting the case is kinda a pain. so i just did all of them and now i know i have all fresh bearings and wont have to keep working on it in the future.. Like when u replace something, something else always seems to break... lol so just get all the bearings at once.... 80 bucks is better then seizing a engine. good luck.

I replaced all my bearing too, I mean why not their not all that expensive, cheap insurance really.

where can I get bearings for that cheap? I ordered one off my dealer and it was 40 bucks.

twowheeled said:

i got the 5 tranny bearings for my kdx200 from the dealer for about $70 for all of them(2 output shaft bearings, 2 primary shaft bearings, and shift drum bearing), you are getting ripped off

Look for a bearing supply store. I dont know how much industrial business is in your area, but if you can take them the bearings they can get them much cheaper.

ebay.

I just wanna add, is it very smart to save money on engine components? Yah the world of motocross screws over the average rider. Parts are to freaking expensive! but to not buy a part from the people who make them specifically for a dirt bike is kinda iffy.... I bought Exhaust O-rings from a local business and they said they were high temp.... bull shit they weren't low temp even. i saved a few dollars but had to ride a moto with a noisy ass pipe rattling around in the head because i wanted to save a few dollars. just dont cheat your engine because it will blow up.

My output shaft bearing went south one day too - but to the point of grenading, scratched the shaft a bit too, I ended up replacing ALL bearings for peace of mind, the output shaft and second and third gear.

Take out the bearings, take them to a bearing supply shop and they will match them up - as long as you don't get chinese knock off bearings - you'll be fine - any of the japanese or european bearing brands are perfectly fine - matter of fact - all motorcycle bearings are made by these companies - in most cases they are the same bearing you would buy in teh bearing store - except 4x as expensive.
There are exceptions like main bearings with the retaining recess machined on the outer chase and such, but even taking a 6203 unsealed and replacing it with a 6203 sealed bearing (pull the seals out) will work just fine since the bearing itself is built to the exact same specifications.
I did all the swingarm and linkage bearings on my son's bike for less than a set of wheel bearings.

sweet, I will do just that. I know a few local bearing stores in town but didn't know if you could just swap em like that.

Rynlar523 said:

the bearings in these motor arnt moto specific, they are just higher grade ball or needle bearings. i have crossed many of the part numbers to timken or sk bearing. you can look up the datasheets for the oem koyo bearings to get the load, rpm etc specs, ussually the replacements spec out better. i bought the tranny bearings from kawasaki because my local bearing house was actually a dollar more on each bearing. my girlfriends kx has 3 different brands of bearings in the rear suspension, from 2 different bearing houses, it was half the cost of a pivot works kit, i didnt need the seals.

Rynlar523 said:

There's not a single bearing in your engine that was made "specifically for a dirt bike". The engineers that design the engines decide what bearings to use based on the commercially available bearings that meet thier projected requirements.

I suggest you go ahead and do it. $100 in parts = $1,000,000 in peace of mind.

If you try to buy non-Kawasaki bearings, make sure they are of the same or better grade (hi_im_sean's comments on load and rating and such).

Chokey said:

The only time I had problems with matching up bearings was on a 07 YZ250 linkage. Seems the newer bikes have very odd, motorcycle specific metric sized needle bearings.