Factory Shift Kits

Many pre-94 EX500s have a tendency to slip out of second gear into neutral. This occurs most frequently on trailing throttle following high revs in second gear. Kawasaki had become aware of this problem and, for the 1994 model, increased the number of engagement dogs on the offending gear pairs from 3 to 5.

I came to use a Factory shift kit by accident. My 1989 EX500 did not exhibit this problem, but at about 19,000 miles a circlip broke on one of the transmission shafts allowing a gear combination to slide freely into its mating gears. This completely fragged more than half of the gears, so I ordered a complete replacement transmission from a salvage yard in California. Never having had a 2nd gear slip problem, I simply installed the replacement transmission without making further modifications (see below, Other Solutions). After approximately 750 street miles, the new/old transmission began to fall out of second gear regularly. I had just split the cases and was not interested in doing so again, so I looked for an alternative solution.

Factory Shift Kits:

The Factory shift kit is nothing more than a stiffer shift detent spring. This so-called kit includes (i) the spring, (ii) an additional gearshift mechanism gasket, and (iii) a Factory sticker. For a retail price of about $30.00, this is not what I would call a bargain. The kit also comes with complete installation instructions.

This stiffer spring puts additional tension on the shift drum and, when the gear wants to slip, holds the drum in its current position. For severely worn transmissions with a great deal of freeplay and/or rounded engagement dogs, the Factory Shift Kit may be useless. My new/old transmission seemed to be in good shape and the shift kit completely eliminated the second gear slip problem. Many people, however, have made this modification with no positive results.

Installation Notes:

I had just recently changed the oil so I leaned the bike on its right side and propped it against a pole in my garage. The oil level on the left side becomes lower and you may remove the shift mechanism cover without spilling your oil. It is recommended, however, that you simply drain your oil prior to this procedure.

Other Solutions:

More permanent solutions include (i) undercutting the gears (a process by which the gear dogs are filed at an angle so that they do not slip out), (ii) rebushing the gears (slop created by poorly bushed gears can lead to slippage) and, (iii) fitting updated second and sixth gears from 94+ spec transmission parts. Some do one or all of these modifications with good results.

Conclusions:

One can say that this is merely a band-aid solution: it merely treats the symptoms but does not cure the disease. When it comes time to split the cases again, I will replace the offending gears with 94+ parts and have it undercut at that time. In general, low-milage transmissions that have not been severely abused can benefit from this modification. I currently have over 7,000 rough miles on this transmission and have yet to experience another slip. Shifting action is noticably stiffer, requiring a deliberate poke with your boot to change gears.