Maintenance & Technical > KX500 Original

KX500 on the street-lost shifting and 3rd gear...

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alward25:
casting flaws, normal

Foxx4Beaver:
funny,there's a thread/post on here from several years ago where 3,4 or 5 guys had all lost 3rd gear and having shifting problems at the same time...and someone posted that "transmission problems must come in waves"....cause mine started missing shifts(neutral shots) and downshifting on it's own under power just last Sunday.

Until you actually open it up...it's really impossible to know what you're going to need.
You might as well order all new snap rings to start...there's 8 of them...6-25mm,1-18mm,and 1-24mm.I'm assuming I sheared one of these(that hold 3rd gear),and is causing my problem.Now,I don't know what your budget is like,but I just ordered a COMPLETE transmission Friday.When I rebuilt it last year,the forks had some wear,and the gear dogs had wear...but everything was still within spec,so I didn't change anything.So I know everything is going to be a little more worn especially with my bike being a 95 and I'm assuming is the original tranny...it just makes more sense to me to replace it all..that way there's less chance of having to open it up again sooner than later,plus that means now I'm stuck riding the 250 which I'm not thrilled about :x...so when I went to my dealer,we ordered the entire tranny,and the entire gear change mechanism.
Total at my cost with 30% discount...a whole $1164.79....and there's some extra costs too...new crank seals,woodruff key,kickstart springs,new rings(why not freshen it up while it's apart),gaskets...about another $250-$275.

It's highly unlikely you'll need to go this far...I only did because I don't enjoy down time...or "having" to ride the 250!...and my K5 will have a "tight" tranny! :-D

Rick james:
Well, I finally scraped together the cash and bought a splitter, gaskets, seals, circlips and a crank puller.  Got the cases split after breaking an arm off of a Tusk crank case splitter and welding the arm back on.  Everything in the transmission looks brand new.  I can see hardly any wear on the dogs, shafts, shift forks, gears or anything.  The top end was also almost completely clean/free of carbon.  The piston inside says ART on one side, anyone know what it is?

I pulled the gears off of the shafts, all of the circlips were in the proper location and looked good, so I put everything back together with the new clips.  The 18 mm circlip on the end of the one shaft didn't really fit on too well, but looks ok. I have put the cases and transmission together without the crank about 5 or 6 times and played around with shifting it. It seems like it's a little sticky when I'm going through the gears, but if i'm spinning the output shaft by hand and I try shifting it, it goes through all of the gears.  It almost seems normal, the same way any bike won't shift through gears when it's sitting still, but I'd rather be sure before I put it all back together. I'm going to pull it back apart and see if I can figure out a way to tell if the shift forks are bent, because at this point I think that may be the only thing that could be causing a problem.

Rick james:
Well crap, I tried putting the cases together, used the cold crank method to get it in the right hand case.  I heated up the right hand case half with a heat gun as well.  The crank dropped right in with a nice thunk and seemed to bottom out on that side.  The tusk puller I bought won't fit onto the clutch side where the c-clip goes, so I'm just relying on the fact that it dropped in.

I applied non-hardening compound to the right case half and dropped the left one on the still cold crank after heating it up.  I attached the crank puller and snugged down the case half.  It went on fairly easily, but after I tightened the case bolts the transmission was too tight to turn by hand.  The crank also doesn't seem to be spinning freely. 

I pulled the left half back off, checked the shift rails, transmission thrust washer, etc and tried doing it again. Same thing. Any ideas?  I left the bearings on the crank as they came off with it and looked to be still pressed on the crank all the way. The cases didn't seem bound up at all when I was pulling the crank through, and the second time I had a friend use the wrench and puller while I wiggled the cases as they were coming together, and still got the same thing.  I really don't want to screw up on this, I'm considering just setting it aside and taking it to a professional who can check the crank and put it back together correctly. I tried whacking the crank with a rubber mallet on both sides and it didn't seem to make much difference, but then again the trans is still bound up so I didn't really beat the crap out of it as it needs to come back apart regardless.

What the heck am I doing wrong? Could splitting the cases the first time have pushed the crank that far out of whack?  Why would the trans bind up when the bolts are tightened?

Pmcg:
With the heat freeze method the case halves should meet. You shouldn't use the case bolts to pull the halves together.

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