80 kz550C trans problems- help!

the transmission shifts fine when its cold but when it warms up it has trouble down shifting. the shifter moves but won't engage/shift into the previous gear. it mostly happens when shifting from 6th to 5th and from 2nd to 1st. any hints, tips or clues would be greatly appreciated

other bike info-

• around 30k miles
• oil/filter change with 20w-50 motorcycle oil less than 500 miles ago
• carbs cleaned less than 100 miles ago

I don't remember for sure, but I think that both those shifts use the same shift fork, so it's a possibility that you have a bent (or worn) shift fork.

It's been a year or two (probably 2) since I worked on a 550 trans, but I think 2nd and 5th uses the same shift fork (there are three shift forks).

Loudhvx is the 550 expert, not me

any way to tell if that is indeed the problem without cracking the case open?

Quirkson wrote:

any way to tell if that is indeed the problem without cracking the case open?

There's other things you can check first, like the shifter mechanism behind the engine sidecover.

I haven't worked on any 550's, I just put the 550 six speed trans in a gPz750.

My 1981 KZ550D1 does the same thing. Shifts great when cold, but is very hard to shift when warmed up. Have adjusted the clutch push rod and changed the oil regularly. Run Valvoline 20w50 in summer and 10w40 in the winter. Bike has 20,000 miles. Wish I knew why it did this? Maybe warped clutch plates or non-stock frictions?

Robert

I had the same problem in 1st/2nd and neutral finding after the motor was warm. The fix was new Kawasaki friction disks (although I replaced the steel plates too). I went through aftermarket friction disks and they slipped way too much, even with new stock springs. I called several speed shops around here and they all said practically the same thing: "throw away the brand new aftermarket disks and put in factory disks". The few extra dollars for the factory disks was worth every penny.

I didn't experience 5th/6th problems though.

loudhvx wrote:

I had the same problem in 1st/2nd and neutral finding after the motor was warm. The fix was new Kawasaki friction disks (although I replaced the steel plates too). I went through aftermarket friction disks and they slipped way too much, even with new stock springs. I called several speed shops around here and they all said practically the same thing: "throw away the brand new aftermarket disks and put in factory disks". The few extra dollars for the factory disks was worth every penny.

I didn't experience 5th/6th problems though.

Thanks Lou, I will be installing new Kawasaki frictions and steels in the near future, along with OEM springs.

Robert

Oh and Steell's being too kind. Definitely not an expert. Thanks, though, Steve!