Slipping clutch 81 KDX 175

[Bark3rd]

Hey all, I have a new set of probs now. The clutch was slipping so I took it apart and found that the clutch discs were stuck together. I had a replacement clutch assembly that came with the bike so I inspected it (appeared to be NOS part-the ENTIRE clutch assembly with cherry non-grooved basket). The clutch plates were stuck on that one too (probably from sitting for years) to I freed them up and bolted everything up. It didnt slip as much but still slips alot, feels like a poorly adjusted rekluse-it revs then slowly catches. I played around with the free play on the clutch cable but this didnt help much. What could the problem be? Is it likely that the clutch pack is still sticking? I got it good and hot. Maybe she doesn't like the Rotella T oil?

Another thing- how much is needed for the clutch spring bolts? I snugged them down evenly (not overly tight) but wondered if there should be a little slack here so the clutch pack can move. After I tightened it you could not wiggle the friction discs at all.

 

[sr5bidder]

you torque the bolts down on the springs I can't remember but 3-5 ft lbs, look it up

did you soak the friction plates in oil before assembly?
Have you looked a parts fitche and see that your not missing anything?

on some bikes there is one plate(usually last one you put in) that is bigger on the inside and there is a big spring washer that fits in there...not sure about yours though

if all else fails try some new springs (I had an xt225 that was slipping and new springs fixed it)

 

[Bark3rd]

I have some good springs from my 81 kx 1225 that are the same length and diameter, but slightly beefier. Maybe these will do the trick. Thanks for the info

 

[sr5bidder]

wow I'd like to see that 81 kx 1225, is that a single cylinder or a prototype radial 2 stroke with 7 cylinders?

 

[Bark3rd]

Ive taken this clutch down 3 times now, everything in it is brand new. It still slips. I have a manual and followed the directions, all the bits are in there. There must be a problem with the actuator arm and/or pressure plate but I cant figure out what it is. I have the cable adjusted with a little free play at the lever and at the actuator arm, Ive gone both ways with the slack and cant dial out the slip. Could it be that there is not enough clearance between the "clutch pusher" (#13114A) and the actuator (internal #13236) so when I release the clutch the clutch pusher is still partially disengaging ? Meaning, maybe I should remove the washer #411? Also, when I tested the "clutch pusher" and pushed it home by hand (as the actuator arm would push it) it clicked and binded a bit, not sure if this is how its supposed to be, not sure how to fix that.

 

[reepicheep]

That washer is there to get things back in tolerance when there is too much slop. Definitely try with it out.

You know when you need the washer because the arm (when reassembled) won't pull through 90 degrees to the cable (where you get best leverage).

 

[sr5bidder]

you should have a little play in the actuator take the cable off to test it out ...if you have play then theres no need to remove the washer

you never did say if you had soaked the plates in oil before assembly?

 

[Bark3rd]

Yes the plates were soaked. The diagrams above (there are two there) are for an 81 and an 82 KDX. One shows the washer, one does not. Weird. I assume the one on the right is the 82 but the diagrams aren't labeled. There is play in the actuator without cable though. Going by the diagrams, my 81 requires no washer.

I am also wondering about clutch hub bolt torque. I use an air gun to tighten it, but I may be letting off too soon (I am afraid of overdoing it). Is it easy to over torque those and cause damage? My airgun has settings 1-4, I used #2 and it seemed to seat it ok.

 

[sr5bidder]

man I would never use an air gun on that app. I use a 1/4 inch drive socket wrench in the palm of my hand you may want to see if you striped the threads.... that would cause the clutch to slip

also when tighting those 4-5 bolts do so 2 turns at a time in a criss cross pattern so they all get tight at the same time

 

[Bark3rd]

Oooh no, I wasn't talking about the spring bolts, I meant the big clutch hub bolt that threads on to the driveshaft. It is a 36lbs/ft spec bolt.

 

[sr5bidder]

nice

I have no Idea besides the clutch springs you pushed it in by hand I use channel lock pliers to do mine maybee I'm just weak!!

 

[Bark3rd]

Sometimes, the simple, obvious solutions are missed in the heat of mechanical battle. After the 4th clutch tear down, I got her buttoned up and went for the "moment of truth" ride. Well, still slipping. Dammit! Then, I look down at the back tire to see how much traction I am getting on launch and notice the rim SPINNING INSIDE THE TIRE!!! Lol, this was the problem the whole time. I am retarded, but now a master of the KDX clutch. It is amazing how the symptoms of a slipping clutch were so exactly replicated by the spinning rim, it spun alot at first, and as speed increased the rim would catch up with the tire and it would "feel" like it had finally engaged. :bang:

 

[regularjoe]

I never thought it couldbe that. I have been watching this thread this whole time to see what you came up with. I have a 80 kdx175 and was wanting to see the outcome just in case I ran into trouble myself.
I guess its good you figured out and it is a easy fix. Thanks for sharing.

 

[julien_d]

Nice!

 

[reepicheep]

I almost got burned by something very similar, now that you mention it. 2000 Buell M2... fantastic bike, but the dogs on 2nd gear got worn and it would "pop" into gear after you got on the gas from time to time. Pretty exciting on a 90 HP high torque VTwin... felt like you just got rear ended by a meteor or something. Anyway, the old Buells had a cartridge transmission, so no big deal... pull off the primary cover, remove the stator / clutch assembly / primary chain, then pull the transmission as a unit. Maybe 1 hour from running bike to transmission on your bench.

Anyway, after fixing it, a year later I felt the same thing. I was about ready to tear it down to see what I did wrong when I replaced the rear tire (which was a really crappy Dunlop D220). It had a minimal (but ok) amount of tread, but I notice a strip down the middle delaminated and exposed some other compound underneath. I was hoping to get another 1000 miles out of the tire when it started coming apart... but so be it, ditch it and put on a Metzler MEZ6 (much better tire anyway, those D220s were downright dangrous before they warmed up).

Lo and behold, the new tire fixed my transmission problem. It wasn't worn dogs half engaging at all, it was that stupid strip of delaminated rubber. It would let the tire spin for about 1/4 rotation, then hook back up. I only felt it in second gear, as that was when I was typically getting the most torque to the rear wheel (first gear I was easy on the throttle so I would not loop it, third gear was geared too high to get that much torque to the wheel).

I was lucky I didn't waste a transmission tear down....

So I second the "thanks for sharing" note... I'll think of this post before I start hunting clutch phantoms if I ever have this problem...

 

[Bark3rd]

Haha, these vintage bikes are earning me my dirt bike mechanic PHD. Ive been riding my whole life but somehow never really got into much wrenching until I started racing alot and messing with these vintage Kawis. Blew the whole morning off today fine tuning the KDX 175 which was blubbering. Cleaned off the ground on the coil (as mentioned in a million threads here), changed plug, and dropped the needle 1 notch and BAM! there's the 2 stroke hit I was looking for. This bike is faster than I thought it would be, I might actually race this thing if I can figure out how to stiffen up the ultra soft forks. I have an 81 KX125 right next to it that I could scavenge the forks off of, but studying the diagrams they sure look identical to me. Anyone know if they are stiffer/valved differently?

 

[sr5bidder]

Sometimes, the simple, obvious solutions are missed in the heat of mechanical battle. After the 4th clutch tear down, I got her buttoned up and went for the "moment of truth" ride. Well, still slipping. Dammit! Then, I look down at the back tire to see how much traction I am getting on launch and notice the rim SPINNING INSIDE THE TIRE!!! Lol, this was the problem the whole time. I am retarded, but now a master of the KDX clutch. It is amazing how the symptoms of a slipping clutch were so exactly replicated by the spinning rim, it spun alot at first, and as speed increased the rim would catch up with the tire and it would "feel" like it had finally engaged. :bang:

did the old girl come with rim locks or had they not invented them yet in 81?

I bet it shredded that tube!! :whoa:

I wish I had an old air cooled kdx to play with...so how is the power ??? is it weak on low end grunt??

 

[julien_d]

A buddy of mine has a kdx175. It is indeed a surprisingly quick machine. I was not expecting that the first time I got on it!

I'm about to have my 200 stitched up, and then I'm going to go back to working on the old '73 250. I miss having the old air-cooled bike as an option. It's extremely fun to ride too.

 

[Joburble]

... I'm going to go back to working on the old '73 250. I miss having the old air-cooled bike as an option. It's extremely fun to ride too.

If you are talking about the old F11 I second that, although I did bust my collar bone on mine. Who woulda thought you could do that, it's not even far to fall :whoa:

 

[Bark3rd]

I went riding today in a technical, rocky place in the Tx Hillcountry and was very pleased with the performance of the bike. I could keep up with my B class buddies and even passed some of them, they couldn't believe it. Great bike, I am going to race it occasionally just for a gag!