'81 650 maxim pops out of second...any help???

please share your experience...It goes in to second but pops out and makes all kinds of nasty noise...I'm soon to be tearing into it and don't know what to look for? Please advise? Thanks, Regunner.

 

Welcome to you troubled brother. This sounds harsh but I'm going to say you've got a serious issue within the gearbox. Not being a gearbox guru, I'll say only that your selector fork and/or gear cluster are in need of renewal, which necessitates the pulling of the motor and splitting of the case. Bummer of a job. Wait for additional opinions, there might be hope out there that I am unaware of. Best of luck to you, wish I could wave a wand for you.

 

Yep, probably due to selector fork and/or gears like Robert says.
The gear teeth are constantly meshed so only thing that engages when you shift are dogs (square tabs) on the side of one gear fitting into holes in the gear next to it when they slide together. The gears are made to slide horizontally by the forks which are levers that push them to one side or the other and problems develope when the edges of the dogs wear off and they become rounded or the forks get bent from excessive banging on the shifter from lots of drag racing, then the gears don't engage all the way or are able to jump apart when torque is applied. The problem is the gears don't go all the way together, the dogs only go half way into the hole in the gear next to it.
The wear on the edges can be fixed with some grinding with a Dremel to square them up again or even undercut them to make the torque pull them closer together but bent forks have to be replaced. The only thing that holds the gears together when they are shifted is a spring loaded detent on the shift drum at the other end of the fork. It's possible the shift drum could be worn or have a broken spring but not too likely. You can take off all the covers and move the mechanism by hand while you watch it to see if it's shifting properly.

 

yep...I have snagged another running engine to swap in for now and then I'll tear apart this one. I'm planning on replaceing the shift forks and either undercuting or replaceing the gears all together. (we'll see how bad things are?) Can I flip the engine on its top and remove sidecovers and split the case without removeing the top end?
I'm getting a complete gasket set and wonder if I'll need either a haynes manual or the xjcd noted on this website? Thanks, Regunner.

 

I've done the case split leaving the head intact. Bit of work but do-able.

 

which covers, other then shifter's, can be taken off?
('m stuck in first and would like to avoid splitting the case)

 

When you take the shifter cover off you can see the mechanism. If you're REALLY lucky, it could be spring #2 or spring #4 in the diagram below. I had the end break off spring #4 in one of my SR500s and it stayed in gear. Otherwise, you're looking at taking the bottom off the motor.

 

yeah... too bad. i thought, i might've overlooked some other cover, that would expose the whole gears thing.

the springs are fine.
now, what's the most efficient way of getting to them shifter forks? someone said they may be the problem.

 

There is only one way to get to the shifter forks. The cases have to be split--the motor has to come out, go upside down, and the bottom come off. No shortcuts unfortunately.

 

split 'em!!! if you havent done it before get a manual and take pictures, its not as bad as it sounds but organization and good note taking are key to a successful rebuild.

 

b0rn

If you area stuck in first, try turning the bike upside down and take off the oil pan and remove the debris from your gearbox. RickCo has a thread about that.

 

the thought of turning the bike upside down is really intriguing... can't find that thread, though. can you post a link pls.

or... was it a joke?

 

A friend stoped by to help with the stuck fasteners on the Black Bike. I also showed him the exRed Bike with its stuck gear. He touched the shifter, - it shifted! Talk about the Magic of Technician's Presence...

Shifter gromet (#39 on the diagram) is ground-to-the bone/broken. Makes me wonder if there's a piece of it floating around somewhere and weither it was that piece that caused the shifting problem, like HalfCentury said.

 

Hmmmm....that's not really a shifter grommet, it's the middle gear case seal, and really shouldn't affect the shifter assembly....it's actually shaped like that (as pictured) when new. Perhaps some of the jiggling and wiggling around of the various bits and pieces that occurred when you took the side cover and shifter mechanism off freed something up?

 

Chacal,

Thank you for the correction.

Please, correct if I'm wrong ...again. But, this IS the ONLY part that prevents shift lever assambly from going deeper into it's little hole and missing shift shaft assembly's teeth, as mine does. And to do that, it would need to be about twice as thick in the place where metal is showing. Therefore my assumption of it being broken/worn out.

whoever made up that name "shift shaft" deserves some kind of English Language award .

 

Chakal, I stand corrected, - a couple of love taps by a baby hammer and the shift shaft assembly slipped right into its propper place, teeth matching perfectly.

As far as debris in the shifting mechanism goes, -
thanks to StereoMind and his Search-Fuâ„¢ for the link to emergency guidectomy: