'90 KX5 missing shifts

[NZ500]

Hey all. I've spent a huge amount of time rebuilding my KX500. I did about 4 hours on the fresh motor and the clutch started slipping. I put in a new full clutch kit and it started slipping again. Have sorted that today by shortening the rod (again!) that goes through motor. The motor is going well and clutch isn't slipping now, but it's not staying in gears when I shift up. Mostly going up into third I noticed it. It's like it's not 'clicking' into that gear. The bike will suddenly rev and probably do not so nice things to my gearbox.

Was supposed to be doing a big event in a couple of weeks but it really is flat out and I think I'll wreck it if I ride it like this.

Any ideas? Am I going to have to split the cases again and replace the shift forks? Maybe riding with clutch slipping has damaged something?

I hate this bike! lol

[Polar-Bus]

1st question why are you "shortening the clutch rod" to rid the clutch slippage ? You definately have some type of incorrect assembly with your clutch. KX clutch systems are simple, and generally extremly reliable. All's your doing by shortening the rod is "band-aiding" the real issue. 2nd question did the tranny jump out of gears before your rebuild? We need much more details pre, and post rebuild.

[NZ500]

Because the clutch rod was to long, causing the clutch not to clamp up properly. The original arm on the left side of motor was rooted and someone has lengthened the rod to compensate for that wear rather than fix the problem causing it. I replaced that arm with a new one when I rebuilt motor. That is why the rod is now to long. The original clutch looked (and measured) like new when I did rebuild so I didn't touch it. I rode it for about 4 hours and when it started slipping I put a new full clutch kit in it with heavy springs. They might have been reliable transmissions when they're new, but this bike is over 20 years old now and has done a hell of a lot of hours.

The bike never ran when I got it. It had a snapped kick starter shaft and then I found the motor was well overdue for rebuild (main bearings stuffed). Once rebuilt I rode it for a few hours before the clutch started slipping and although it wasn't very nice to shift compared to other newer bikes I've had it wasn't missing so bad (about as smooth as I'd expect a powerful bike of this age to shift).

I can still put the bike in gear with the clutch pulled in without it trying to take off or stall.

[littlewing78]

I had a similar problem.  Might be the same might not. 
http://www.kxriders.com/forums/index.php/topic,9638.msg76078.html#msg76078

[NZ500]

I had a similar problem.  Might be the same might not. 
http://www.kxriders.com/forums/index.php/topic,9638.msg76078.html#msg76078

Thanks. That would be an easy fix. Maybe a spring has popped off when I had the cover off?

[NZ500]

Took it for a test ride today, definately has issues (I bent the gear lever away from ignition cover and wanted to see if that stopped it).

Pulled cover off and clicked up gears. When shifting up into third this is what it's looking like.... the wee roller isn't clicking into the slot all the way. I'm going to go keep working on it but if there's anything that looks obvious please let me know.

[NZ500]

It feels like there's something inside (bent shift fork?) stopping it go further that there because I can't turn that gear selector from the outside to it clicks into third gear. It was in the groove in second gear.

I have done about 150-200km riding without this issue after rebuilding the motor. I'm thinking I might have forced it into gear at some stage and bent a shift fork?

[Goat]

It sounds like 1 of 2 things to me. Both have to do with the shift fork. Could be bent or the pin that rides in the shift drum is marred up, bent, miss aligned, ect. ect.

Have you split the cases yet?

How did they lengthen the clutch rod? Seems pretty silly for an easy fix that isn't very expensive.

[NZ500]

Hi Goat. I haven't had a chance to split the cases yet because I've got quite a few other jobs to do.

There was signs of weld on the side of the pushrod. No idea why I guess they were just tight/broke. The arm (clutch detent? I think they call it?) that pushes the rod was absolutely stuffed and had been welded up before to get some more life out of it too. Factory parts for any thing here (New Zealand) are a rip off compared to America and they're rarely in stock so I guess people are more likely to make do. The rod is over 1mm shorter than stock now but I guess that doesn't matter so long as it's doing what it is supposed to do.

Will repost when I've got motor apart. Might be a while now though.

[NZ500]

Pulled motor apart today. Found the shift drum has a chip out of it (see pic). Yeah, the dowels/pins on each shift fork are worn past service limit too. One especially from going over top of that chipped piece. Going by the wear marks the pins don't sit in the drum very far? looks like they're only half way into the groove. Is this normal? Doesn't look like there's anything I can do about it though.

Have just ordered a heap of parts including 3 shift forks and the shift drum assembly among other things. I'm sure I could fix it but I really don't want to pull this thing apart again.

Also included a pic of a couple shafts I made today that bolt to a puller (which I also made) for splitting the cases. It worked really well. I thought it would have taken a lot more to get apart than that (was worried about using only two m6 aluminium threads at first). Didn't need it last time because bearing journals were worn out and it just tapped apart.


Edit: can't upload pics because it says upload folder is full

[1989kawasaki]

then you have to host the pics through photobucket