KAWASAKI KH & S SERIES FORUM

tony_d123 · Posted: Sun Aug 02, 2009 3:35 pm Post subject: KV75 gearbox expert?

I need a KV75 gearbox expert, so I guess that means Stale!

Had a proper look at my KV gearbox today. Both selector forks are 5.0mm thick (when I fit the NOS one) and the groove in the shifter or slider is within standard limits.

Everything else looks OK apart from the dogs on the 2nd gear (output shaft) and the corresponding ones on the shifter are worn, mainly on the faces where they slide across each other. The sides are still fairly square, although slightly rounded at the top.

If I cannot get a replacement, I was thinking of dressing the dogs and trying to square them up, but as the sides are not too bad and the faces now have a matching profile I may do more harm than good as I will reduce the height. Do you agree?

Why are they worn so much on the faces rather than the sides, has something (other than a boot!) been putting pushing them together? Is this why the selector fork was so badly worn on one side and broke?

tony_d123 · Posted: Sun Aug 02, 2009 7:08 pm Post subject:

Has anyone had dogs welded & re-ground to the correct profile?

180kid · Posted: Sun Aug 02, 2009 7:42 pm Post subject:

have you got the part number ?

The Wolfman · Posted: Sun Aug 02, 2009 9:02 pm Post subject:

Worn?? one of those dogs looks to have a big chunk missing or is it a trick of the light?

looks like 13131-032 has it got 26 teeth?.....any advance? Also used on the MT1 series.

The gear will probly be case hardened which is why once the surface is penetrated the metal disappears at a rate of knots. Any work on the gears will then need the surface hardening again, if you look in your local Yellow pages there wil probly be gear engineers around you, but their work will be pricey.

A good S/H or NOS is a good start.
_________________
:
I used to be a Werewolf, but I'm alright Noooowwwwww!!

ståle · Posted: Sun Aug 02, 2009 9:26 pm Post subject:

This is common, Tony. You'll need a new or at least a good 2nd gear. The 2nd gear is the weakest link in the KV tranny. What usually happens is that if the engine has too much rpm in 1st before changing to 2nd, the 2nd gear dogs will take a good beating when changing gears. Over time this will result in rounded dogs on 2nd, that will push 2nd and the shifter away from each other. This again will result in the gearbox locking up between 1st and 2nd, then with the shift fork in tension, and it breaks. Mine was excactly like yours.

You have a new fork, get a good 2nd gear and a good shifter. Then have them undercut on the 2nd gear side (recommended !!) My mate has undercut all our KV's using an angle grinder and cigarette paper

Works great !

tony_d123 · Posted: Sun Aug 02, 2009 9:30 pm Post subject:

Thanks Stale, you confirmed what I feared. These KV gearboxes must be made of really crap metal, considering the relatively low loads going thro' them.

ståle · Posted: Sun Aug 02, 2009 9:33 pm Post subject:

That should be it, Gra. Same on all the 75's.

ståle · Posted: Sun Aug 02, 2009 9:39 pm Post subject:

The ratio gap between 1st and 2nd, combined with a centrifugal clutch is a disaster waiting to happen.

g6mow · Posted: Sun Aug 02, 2009 9:44 pm Post subject:

So when are you getting the gears repro'ed Stale

, think I'll need some too.
_________________
www.kawasakitripleparts.com
sales@kawasakitripleparts.com

ståle · Posted: Sun Aug 02, 2009 9:45 pm Post subject:

Here's a used shifter. Cheap too:

http://cgi.ebay.com/ebaymotors/TR...MotorcyclesQ5fPartsQ5fAccessories