K75S Junping out of second gear

[120600]

My 88 K75S is jumping out of gear in second under heavy acceleration. Trans fluid is good and I'm wearing the same boots as always. Could this really be my shifting?

[35634]

Could be a bent shift fork, damaged gear or shift drum. Don't think there is any
cheap fix, maybe E-bay for a nice used tranny.

[lostboy]

If this is a new problem, you probably just need to replace the shift drum. Early drums (like yours) have a coating over a fairly soft alloy. This wore quicky, resulting in the gear not being properly engaged. Later drums are uncoated but the alloy is much harder.

[BeemerMike]

My 88 K75S is jumping out of gear in second under heavy acceleration. Trans fluid is good and I'm wearing the same boots as always. Could this really be my shifting?

Jumping out of second when you shift into second and then start accelerating again? Are you preloading the shift lever for the shift? There is another recent thread discussing this issue for Oilheads.

[breyfogle]

My 88 K75S is jumping out of gear in second under heavy acceleration. Trans fluid is good and I'm wearing the same boots as always. Could this really be my shifting?

This is a mechanical problem with the expensive stuff inside the transmission. It will only get worse. My K75S is doing this exact same thing. At first, I had to accelerate HARD, up hill, to get it to jump out of second gear. At first, I just thought that I probably made a sloppy upshift. Eventually, it began to jump out of gear on level ground accelerating normally away from stop lights and things. Right now, second gear will not take ANY positive torque at all. I have learned to just go from 1st to 3rd all the time.

The logical fix is to just find a low mileage used transmission. Should be much cheaper than paying a good technician to rebuild a 20 year old tranny.

[scbmwrider]

The logical fix is to just find a low mileage used transmission. Should be much cheaper than paying a good technician to rebuild a 20 year old tranny.

Mine was jumping out of second gear and when I changed the fluid and found this stuck to the drain plug;

http://picasaweb.google.com/lh/photo/ra_MGd2e2JS7APVKanbbIw?feat=directlink

Well the search was on for a new to me gearbox. Think I paid $350 for one.

If you have parts floating around in your box your rear tire could lock up. This causes a VERY high pucker factor. DAMHIK

[breyfogle]

Mine was jumping out of second gear and when I changed the fluid and found this stuck to the drain plug;...<snip>...If you have parts floating around in your box your rear tire could lock up. This causes a VERY high pucker factor. DAMHIK

I had considered that possibility but in my case the problem slowly got worse over maybe 2 years of riding and nothing out of the ordinary has come out the drain hole. I think this indicates a wear problem. However, you are right about hard parts swimming around in a transmission.

[120600]

Thanks for the replies. I only have 40,000 miles on this K75. Bought at 32,000. I've done one fluid change using Phillips 80/90 about a year ago. Could this breakage happen in a box with only 40K miles on it?

[PGlaves]

Thanks for the replies. I only have 40,000 miles on this K75. Bought at 32,000. I've done one fluid change using Phillips 80/90 about a year ago. Could this breakage happen in a box with only 40K miles on it?

Sure. A shift fork can be bent with one stomp or upkick. More likely the dogs have rounded edges. Every time it jumps out of gear increases the wear and tear on the shift dogs.

[120600]

OK Thanks. I will look for a low miles used tranny. What year did they start using a harder alloy for the shift drum? Lostboy do you know? Will all K75 and K100 trannys fit? Are there any internal (gearing) differences?

[lostboy]

I believe the improved shift drum arrived about 1990. Any K75-K1100 gearbox will bolt up. Gearboxes for 16-valve bikes have a taller 5th gear, which you may like.

[BeemerMike]

In the June issue of MCN, Ken Condon has a good article on upshifting and downshifting. Upshifting? "Preload the shift lever."