Topic: 78 CB750K misses upshifts into 3rd sometimes

[cookindaddy]

I tried to make the title say it all.

On a great but hot 250 mile ride this weekend I had time to pay attention to this. It doesn't happen every time, maybe 10% of the time, but it is often enough to be annoying. I'm clutching and pulling up the shifter with my toe and then I notice that the revs go up with the throttle but there is no connection, it's like it's in neutral. So I back off on the throttle and do it again and it always engages the second time.

The other gears engage just fine on both upshifts and downshifts. The clutch seems fine. I do have the same problem as others locating neutral with the engine hot and stopped but I don't think that's related or could it be?

Any idea what the source/cause might be? I hope it is not going to make me tear the engine apart again to fix it. If there was a way to localize what I'd be looking for that would help.

Thanks, George

[Fritz]

Could have several different causes.

- Shifter mechanism
- Bent/worn shifting fork
- Worn dogs on gears

Before you dig into the tranny, have a look at your shifter mechanism.
I had a similar problem a couple of weeks ago. Missed shifts from time to time, most of the time from 2nd to 3rd. The problem got worse until I could not shift into 3rd anymore. The reason was a screw that worked itself loose on the shifter drum, so that the "cage" on its end started to move sideways.
Locktite and a screwdriver fixed it. While I was at it, I changed oil and now it shifts like a dream again

Ceers
Carsten

[NewOldSchool]

Iv'e developed a shifting habit that seems to work very well.

1) Preload the shift lever by lightly pulling up with your foot like you are going to shift.
2) Now shift as you pull in the clutch, let off the gas a bit as always. (all this in one fluid motion)
3) Get back on the gas and let the clutch back out.

The clutch lever will almost act like a "trigger" for the next shift if you preload the lever lightly. Its all about the timing.

You will get a lot less miss shifts and false neutrals by doing it this way instead off pulling in the clutch, shifting, letting clutch out.

[rickmancr750]

I've been riding bikes for nearly 50 years and have found a similar problem with my 750. The difference is that it's clutchless shifts that seem to make it miss third. Every other gear is fine. All my dirt bikes- fine. My RDs - fine. My SR500 - fine. All shift fine and smoothly without the clutch (even though Rick doesn't have a cush drive rear end!), except for 3rd on a Rickman SOHC4. (I *should* be able to rule out operator error)