Topic: CB650 won't shift into second

[mdhutch]

First time posting on here, my fairly new (to me) '82 650 nighthawk, the oddball cb650.

First bike, first season riding it (bought it last fall just in time for the terrible weather to hit here in michigan). At the beginning of this summer I had an idling problem so I rebuilt the carbs and discovered it was an air leak.I replaced the carb insulators and a bunch of the bands that hold all the intake parts to the airbox. I was happy it was that simple, and the problem was gone.

Now, that was minor, and my real problem is this;

I began having problems where I'd find a false neutral (or actual neutral, probably) between first and second, and sometimes between fourth and fifth. At first I wondered if I just wasn't shifting fully from time to time. It only happened occasionaly, but started to get worse. Then it fell out of second into neutral a couple times at the beginning of the month. The next week, on my way to work, it stopped shifting into second altogether. 

My assumption is that the teeth are worn on the 2nd gear, and I'm just wondering if there are any other possible explainations. From what I've read, it sounds like the culprit. Unfortunately, I don't think I trust myself to split the case (the service manual has a way of making things sound easier than they are). 

Also, a lot of the transmission parts are discontinued, of course.  Did any of the different sized sohc/4's have the same transmission, if I were to look for used parts?

[scunny]

pull the clutch cover off and check the selector drum, that can cause problems.

[Hush]

+1 on what Scunny suggested, always start with the least invasive attack possible.
Drain your sump oil and remove the right hand side casing cover, there you can clearly see the gear changing mechanism.
With the bike on the main stand you should be able to run the selector through it's full range of gears, turn the back wheel slowly if the gears are hard to engage doing this.
Check that the small spring that holds the selector wheel down is still attached to it's anchor point.
Apart from this visual check there is little that you can actually do without splitting the cases, worn/bent selector forks as opposed to your theory on missing teeth seems more likely.
Another thing I would suggest before even the removal of the side cover is to readjust your clutch, slacken the handlebar lever adjuster right off, slcken the cable adjuster under the right side of motor and then the clutch actuating nut and screw.
Now from the bottom work your way back up, adjust the screw in until it touches the clutch pressure plate then back it a fraction, tighten the holding nut, now adjust the cable under the engine, now back up to the handlebar and set the lever where you feel you want it.
Correct clutch adjustment can give riders the false impression that something more serious is going on....good luck....Hush.

[mdhutch]

Unfortunately, I just got out of gallbladder surgery, but once I'm back out and ready to ride, I'll take a second look at it. Thanks for your help!

[KingCustomCycles.com]

Losing gears was common on those.  My neighbors was a broken shift fork that fell into the transmission and locked everything up.  He did a total rebuild. Just as common is the shift selector damage mentioned above.  Keep you fingers crossed it is an external fix like that and get well soon.  :-)