Topic: Trans Problem

[fireeight]

Hey guys, I just finished rebuilding my 78 750K (I'll post pictures shortly). I rode it for a full season last year with no transmission problems, but after re-mounting everything, and giving it new oil (Rotella T6), she won't go any higher than second gear. Occasionally, it'll die on deceleration in first gear, too. I did replace the clutch switch on the left-hand grip today. I'm not sure if changing the polarity of that switch could have anything to do with this. Other than that, she fires and runs fine. Is there anything oil, or oil-pressure related that could be causing this problem?

Thanks,
Nate

[fireeight]

Edit - pictures!
https://imgur.com/a/UK3L1

[NobleHops]

I confess I was expecting pictures of the transmission. Did you take any photos during reassembly? If so, post those.

My wild ass guess is you did not orient the shift drum and forks correctly. Did you go any disassembly of the transmission gear clusters? And did you inspect/measure the thickness of the tips of the shift forks and compare to the wear limit?

The bad news is that you're going to have to split the cases in all likelihood. The good news is you can leave the top end and crank alone.

[fireeight]

I didn't do anything inside the transmission itself. I did replace the trans cover, so I'm guessing that something was thrown out of position during that.

[700504]

Hey guys, I just finished rebuilding my 78 750K (I'll post pictures shortly). I rode it for a full season last year with no transmission problems, but after re-mounting everything, and giving it new oil (Rotella T6), she won't go any higher than second gear. Occasionally, it'll die on deceleration in first gear, too. I did replace the clutch switch on the left-hand grip today. I'm not sure if changing the polarity of that switch could have anything to do with this. Other than that, she fires and runs fine. Is there anything oil, or oil-pressure related that could be causing this problem?

Thanks,
Nate

Did you replace the clutch? Soak the plates before install? You can 'hot wire' the clutch switch to rule that out.

[fireeight]

I did not. Like I said, the only change on the bottom side of the engine was replacing covers. I also got a solid season of riding with no such issues before the engine was removed for paint. It will shift freely between 1,2 and 3 while the bike is off, and won't go above 2 while it is riding. The trans is my kryptonite. Could this be as simple as clutch tension?

[70CB750]

I had the same problem with my 78 SuperSport. It would not shift from 2 up. I went quite bananas about it with no results, finally I opened it and there was nothing wrong at all. I put it back together and for one ride it shifted fine and than it went bad again.

I endede up taking out the neutral arm from the shifting linkage and running extra zinc in the oil. After 1000 miles without the neutral arm I put it back together and now it shifts just fine. It just needed to be broken in I guess.

[fireeight]

So, now it's stupid question time: is this something that I can assess with the engine in the frame? Also, does anyone have the FSM reference? I've got a Clymer manual. Looks like I'm gonna need some help walking through this.

[70CB750]

My thread:

http://forums.sohc4.net/index.php?topic=147098.0

Manuals:

http://forums.sohc4.net/index.php/topic,17788.0.html

[70CB750]

Some more info

[70CB750]

and

[Swoop]

FWIW"........ Before removing the motor. I would remove the transmission cover and then test it running through the gears, turning the back wheel. If the problem goes away look for interference issues. If it persists...look for something that is hanging up on the shift drum/linkage.

[70CB750]

FWIW"........ Before removing the motor. I would remove the transmission cover and then test it running through the gears, turning the back wheel. If the problem goes away look for interference issues. If it persists...look for something that is hanging up on the shift drum/linkage.

+1, chances are there is something wrong in the shifting linkage.

[fireeight]

That's going to be my first step. I'll report back with pictures once I get the trans cover off. Probably tomorrow afternoon.