Kdx- Trans Or Clutch Issue

sanstoetter · Mar 3, 2015

I just picked up a 93' KDX for a steal knowing that it had trans/clutch issues. Now that its in my possession I'm going to tear into it this weekend, but I wanted to test the waters to see if anyone's dealt with this issue before. That way I'll have parts ready to go, and maybe go for a ride this weekend.

Right now the bike starts up well in neutral if the clutch is pulled, but rolls as if in 2nd gear once the clutch is let out... but still slipping quite a bit (Enough to pull me up a small hill at 15mph). If I shift out of neutral into any other gear the rear wheel locks up. The motor also stalls if I let out the clutch in gear.

Do you think this is an improperly installed clutch, or something more major possibly jamming the gears?

jaguar · Mar 4, 2015

You can't know unless you tear into it. Hopefully it's just a clutch problem. Otherwise you'll have to split the cases.

sanstoetter · Mar 4, 2015

Thats what I figured. I'd just hoped that someone else had run across these symtoms before, and I've already ordered a gasket set in case I do have to tear it down.

sanstoetter · Mar 4, 2015

I started taking the clutch side off today, and visually everything looks fine. I did see 2 metal slivers roughly 0.3mm x 2mm, but I did not see anything worn/broken. Are both of the clutch washers supposed to be the same? The washer in the basket seems like it could be slightly larger diameter. I plan to get a smaller magnet to see if I can find metal anywhere else.

Do any of you see anything glaringly out of place?

sanstoetter · Mar 4, 2015

In addition:
1st Gear- When spinning the rear wheel... the shaft rotates roughly 15 degrees.
Neutral- When spinning the rear wheel... the shaft rotates without any interference.
2nd Gear- When spinning the rear wheel... the shaft rotates roughly 80 degrees.
3rd Gear- When spinning the rear wheel... the shaft rotates roughly 100 degrees.
4th Gear- When spinning the rear wheel... the shaft rotates roughly 180 degrees.
...5th/6th followed the same trend.

jaguar · Mar 4, 2015

the metal shavings could be inside the gearbox and preventing the gears from turning, like if you stick the screwdriver into the meshing teeth of the clutch basket and the primary drive gear to keep them from turning.
take the crankcase all apart, replace the chewed up parts (probably the clutch shaft gear), put it all back together and JBWeld a rare earth magnet to the end of the drain plug (Radio Shack #64-1895) to collect the shavings you missed once you go riding. Ride and then drain the box and look at the final shavings and metal bits the magnet prevented from doing further damage.

sanstoetter · Mar 5, 2015

I went ahead and ordered a flywheel puller along with a steering wheel puller last night in anticipation. Hopefully it'll come apart relatively easily, and it'll be something relatively cheap. Anything else I should check out, or upgrade while its apart? I do plan to clean up any carbon build up, replace seals, new gaskets, check piston/cylinder for marking, and check the rod bearing play.

jaguar · Mar 5, 2015

on my '89 KDX200SR the left side bearing for the clutch shaft went out twice due to letting the oil level go too low. Too low was less than about 110% of the recommended level. I knew it was gone by the movement in the clutch shaft which was helpful to know before splitting the cases.

sanstoetter · Mar 6, 2015

How much play is too much? I checked mine out this evening, and it felt like roughly 1mm of side-to-side play.

jaguar · Mar 7, 2015

you shouldn't be able to feel any play laterally.
(Just to specify, I mean moving the clutch basket up and down or left and right. 1mm of play "in and out" is ok.)

sanstoetter · Mar 7, 2015

I noticed today the carb is not the stock carb, but a Chinese 34mm flat slide (Koso Brand). I have yet to ride the bike, but will this be sufficient to get rolling? It seemed to start well, idle well, rev well, but due to trans stuff I have yet to ride under any load.

jaguar · Mar 7, 2015

the older 200s came with 34mm carbs

sanstoetter · Mar 8, 2015

Well I think I found the culprit.

Looks like the right gear (3rd/4th Input) right cannot mesh with the left gear (5th Input) correctly. To me it looks like 5th gear should be able to rotate one spline, and work correctly.

I've ordered an FSM, but since I do not have it yet, and if I need to order something I'd like to get on the way ASAP. I just can't get my head around how a gear would be on the wrong spline, and have ever moved under it's own power.

sanstoetter · Mar 8, 2015

Also it looks like I should probably replace the piston/rings while it's out. Any preference on Wiseco, Pro-X, or OEM?

jaguar · Mar 9, 2015

Could it be that the previous owner reassembled the trans incorrectly?

KylePeterson · Jun 25, 2015

sanstoetter said:
Well I think I found the culprit.

Looks like the right gear (3rd/4th Input) right cannot mesh with the left gear (5th Input) correctly. To me it looks like 5th gear should be able to rotate one spline, and work correctly.

I've ordered an FSM, but since I do not have it yet, and if I need to order something I'd like to get on the way ASAP. I just can't get my head around how a gear would be on the wrong spline, and have ever moved under it's own power.

soak it in ATF for a couple of days, move it all around, then soak it again. might have gotten some clutch material in the bushings, or jammed up a gear spline.

then try again

Kdx- Trans Or Clutch Issue

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