Shifting problems and grinding

[TalonX]

I have a 1983 GS750ESD I bought in July with 28,4xx miles on it that just turned 30k which has been having some difficulties with shifting. Both under hot and cold conditions when I take off from a stop more often than not it shifts into neutral when I try to shift 1-2. Sometimes 2-3 and 3-4 fail to shift when I flick it up too. The 1-2 shift failing can be rather scary in traffic as you can imagine. It doesn't matter if I'm low revs or high revs it has an equal chance of happening. I know, intermittent problems are the hardest to diagnose. I'm certain it's not just my foot not flipping it up high enough because I flip up until I feel resistance as I was taught.

Downshifting 5-2 is usually fine but 2-1 grinds once in a while and sometimes it gets stuck in neutral going 2-1 with 1 basically being 'locked out' which says to me it's probably the shift forks if it's like a car but obviously it's a bike so that might not be the case.

The manual I found online doesn't seem to really have much of anything about the transmission for my bike so I couldn't really go through any diagnostic procedures. Where do I start?

[cowboyup3371]

I would look at the clutch adjustment first, the cable second, and then possibly spec out your springs and plates to make sure everything is correct. Beyond that, did you already download the service manual from Basscliff's site yet?

[TalonX]

I did download the manual but there isn't really much regarding the transmission in it. Is the transmission the same between the models? Maybe one of the other manuals would be a bit more descriptive.
I did attempt to adjust the clutch cable but I'm not completely certain what they mean by 'play' in the clutch cable? When I undo the lock nut and wiggle it it should travel up and down 4mm/1/4" correct? I also undid the lock nut on the transmission, turned it about 1/4 turn and felt resistance and undid it the same amount so I guess that was already correct.
After I did this everything kept acting the same, intermittently missing the 1-2 shift.
Regarding the springs and plates on the clutch I am waiting for the gasket to come in and when it does I'll take the clutch out to take a look at it and change my oil for 15w40 Rotella-T. If the clutch is shot as I suspect it may be considering the previous owner modded the bike and I suspect didn't drive like an old lady (not that I do either) I am considering getting one of those upgraded APE extra plate clutches with half stock half heavy springs with the new clutch nut to improve the desire of the clutch to actually shift at high rpm. Is that worth the time and money for a 750 or does my bike not make enough power to justify it? I think either way I'll get that upgraded nut since every thread I've read about the clutch seems to agree it's a good idea.

[TalonX]

Any more advice anyone?

[Agemax]

a badly worn or poorly adjusted chain and sprockets will give you shifting problems

[TalonX]

I'll have to check it out. The chain doesn't look overly worn but how exactly would you tell?

[Agemax]

general condition, is it dry? are the sprocket teeth worn and spiky? is it too loose or too tight?

[TalonX]

I double checked the chain it seems to be within spec maybe a bit stretched so I adjusted it and I double checked the clutch adjustment so that should be ok too though what "play" is I'm still not clear on. I guess next on the list is to pull the clutch and check if it's within spec. I'm due for an oil change anyway.
Is that upgraded APE clutch nut really that necessary?

[blowerbike]

I double checked the chain it seems to be within spec maybe a bit stretched so I adjusted it and I double checked the clutch adjustment so that should be ok too though what "play" is I'm still not clear on. I guess next on the list is to pull the clutch and check if it's within spec. I'm due for an oil change anyway.
Is that upgraded APE clutch nut really that necessary?

not on your model.

[tatu]

4mm of play is too much 2mm is plenty. play is the amount of slack on the lever before the clutch starts to activate.
It sounds like a clutch dragging problem to me.