Maintenance & Technical > KX500 Original

Fixing problems with new (old) bike. - Running

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MeanGreenMachine:
Honestly, I was dreading what I'd find inside to the point of dragging my feet, but it appears that everything looks pretty good so far. All transmission components appears to be in good working order (except that output shaft splines - I'll need to replace the shaft).

The output side crank main where the looseness was most noticeable doesn't look catastrophically failed. The core moves a little bit when prodded with a screwdriver and it's a little noisy when turned by hand, but thankfully the OD of the bearing appears firmly pressed into it's bore in the case. There's even a cast in iron sleeve that it rides in, which is a reassuring touch, especially with the mighty 500. I think that the problem is the crank journal - it slipped out of the bearing without any resistance, and the journal surface looks a little chudded, like it's been rolling/spinning a little. Will most crank rebuilders be able to spray/weld/sleeve/chrome and grind this back to spec?

I will need to investigate the engine and transmission innards in detail before I know for sure, but so far the damage tally is:

Topend:
- Possibly stock, 23 year old bore needs a replate.
- Cracks between KIPS booster ports and central port
- Pin shaped extension on one KIPS drum valve broken off, but seems to be holding the valve in place anyways
- Exhaust spring mount worn completely through in one place

Bottom end:
- Rod/bearings worn out
- Output side crank main bearing worn out, corresponding crank journal worn
- Transmission output shaft/sprocket splines damaged
- Kick start idler gear bushing wallered out

External
- Needs new fuel tank
- Kick starter broken
- Need to investigate rims/spokes for tension/true
- Front pipe mount broken off next to engine
- Threaded insert for side plastic missing in subframe

- Whatever else I haven't discovered yet!

Time to tally up the damage one last time in detail, start planning/budgeting, getting parts shipped out, and doing other work while I wait for them to come back...

sandblaster:
Be sure to get all new cir clips for your trans...
Replace them all...

MeanGreenMachine:
Oh yeah! That's a good idea... Any other must change/problem parts while I'm in here? Are worn circlips usually the cause of losing 3rd gear and other problems?

Also on another note, does anybody know if a crank rebuilder typically offers a service to weld or chrome up bad journals and regrind?

bansheedave:
I just rebuilt my kx250 bottom end due to a circlip breaking apart. Took out a gear and allowed the gear to rub the shift for. Grooved the fork but didn't damage it to bad. New clips equal cheap insurance.

MeanGreenMachine:
Ok guys... This is the part where I sacrifice (the remains of) my wallet to the great entity that is Kawasaki. I've fully disassembled the trans and every last bit of the engine, and prepared "KX Casserole" - I had a pretty easy time getting all the bearings removed from the case halves with the oven method.

It turns out that I spoke too soon, and found more damage in the transmission. As you know, the output shaft is boned due to badly worn chain sprocket splines. Ok fine. I found today that 4th gear (labeled 13260-1020 on the exploded diagram) is wallered out and the input shaft is galled in between the 2 circlips where it spins. So it looks like I need input and output shaft, and 4th gear... There is a trans assembly out of a 91 up on eBay right now for less than it'd cost for the shafts and gear. How common is this problem? Where does 3rd fail? How likely is it that these parts could come with the same problem?

[edit]: The bearings that I extracted from the case halves are the same as Motorrad mentioned in his thread:

Main: 2x Koyo 6306
Trans (L): NTN 6305, NTN SXO391 (OEM#     92045-0013)
Trans (R): NTN 63/22C3 (Plastic cage, of course...), Bushing (OEM# 92028-131)

Shift Drum: NSK 6905
KIPS governor: 608 (Make unk.)

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