Second gear disengaging

I just bought a 1980 CB900C (drive shaft) for $500. 28,000 miles on it. It
didn't run very well when I got it and still needs the carbs cleaned.
However I am more concerned about the gears. It has a HI-LO tranny. It does
not matter weather I am in HI-or LOW gear ratio the transmission slips into
neutral from second gear or jerks in second gear then slips out. I can just
skip through second and go into third with no problem.

So, question is what is wrong here. Teeth missing, pressure plates out? I
don't know anything about motorcycle transmission so I sure need help on
this one.

Thanks, Jason in Dallas

 

In addition to the above there is a device called a shift fork that
follows the drum and moves the gear in and out of it's engagement
position. After the trans has jumped out of gear a time or two the
fork can become permanently bent and you can replace the affected
gears with new ones only to have the problem re-occur, unless the fork
is replaced as well. A bent shift fork has telltale wear at the top
of one side and the bottom of the other (the affected areas will look
scraped and burnt). This stuff is easy to fix if you're mechanically
inclined, but if you pay a shop to do it, it would cost more than a
bike like this is worth.

Bill Smith