Inconsistent shifting

bosco659

bosco659

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I had a chance to get the ‘79 out on the road today for a first ride. Got the engine running very smoothly.

When I took it for a spin, the transmission shifted smoothly from neutral to first, then first to second, the occasionally when I tried to shift from 2nd to third, the gear shifter wouldn’t engage and the transmission remained in 2nd. Then I’d come to a stop, try again and all would be good with nice smooth shifts through all gears with no tranny noise. When it gets “stuck” in 2nd, and I go to shift to third, it feels like the shifter mechanism is just barely catching the shifter drum and skips by. Maybe a weak or missing spring?

Clutch properly adjusted. On center stand goes through all the gears without issue, with both motor running and off.

Any thoughts or recommendations would be appreciated.
 
Last edited:
JAT. Worn or bent shift fork.

I lived with a broken transmission for many years because I didn’t want to open it up. Once it’s open, the fix is easy. Hopefully, someone has an easier fix.
 
Ontario should be cold this time of year I would wait a while if possible
There is then adjustments to be performed on the shifter mechanism before going deeper in

thereabouts please look in a manual


1646941934088.png



1646941988503.png
 
I removed both side cases. Here’s what I see on the clutch side. Really nothing to see on the left side. Noticed the shift shaft has about 1mm or more side play (axial - left to right and no noticable radial play. All springs have good tension. Turning the clutch shaft by hand and rotating the star wheel, the transmission shifts smoothly into each gear and to neutral with no hang up. I did notice the spring loaded lever on #1 above, does not sit in the Center of the star wheel assembly. If I push the shift shaft to the right, to take up the 1mm play, the lever rubs on the inside of #5. Wondering if this can make the lever hang up a bit to prevent it from engaging the pins on the star wheel?

No matter what I did, I couldn’t replicate the hang up between gears with the bike on the lift.

Picture 1 shows the lever pulled to the right and it sits on the wheel, not inside. I see some wear marks on it on the lower left.

Pictures 2, 4 and 5 show the lever being off Center and rubbing on the inside of the star wheel.


B94F2987-E884-4E29-8B66-32C9444AE278.jpeg
5421C193-D594-4648-AF51-E2CB629C9578.jpeg
CE62DCC7-D446-4786-B90D-60F5A0ADEF42.jpeg
D1E93CAE-B9F8-44F1-A719-BF261298BD73.jpeg
1EC0AC58-2D13-4542-A3A4-F7B9390B301C.jpeg
 
It looks as though your linkage isn't centered. There's an adjustment in the book.
Before you do that though... I had shifting problems on my SG shortly after I restored it. It turned out to be binding under the left side... between the shift shaft and the chain guard. A piece of metal worked it's way between the two and the shifter wasn't returning to center. Feel any binding of the shifter?


Untitled.png
 
I'd say adjust it and center it up, maybe it will help. What have you got to lose? My '78 will miss the 1st to 2nd shift sometimes, catching a false neutral. I adjusted it offset similar to what yours looks like now, hoping it would give more travel and rotation of the star during upshifts. It didn't help, lol. Eventually, I will probably set it back to centered. I just need to be very deliberate when making that 1st to 2nd shift.
 
Jim said:
It looks as though your linkage isn't centered. There's an adjustment in the book.
Before you do that though... I had shifting problems on my SG shortly after I restored it. It turned out to be binding under the left side... between the shift shaft and the chain guard. A piece of metal worked it's way between the two and the shifter wasn't returning to center. Feel any binding of the shifter?


View attachment 209422
Click to expand...
Interesting about not being centered, I’ll look into that. On the LHS, the chain guard for the shift shaft may have been rubbing on the shaft but it didn’t seem like it was hanging the shaft up at all. Pushing the shaft assembly by hand on the clutch side, everything seemed free and returning to “Center”.
 
5twins said:
I'd say adjust it and center it up, maybe it will help. What have you got to lose? My '78 will miss the 1st to 2nd shift sometimes, catching a false neutral. I adjusted it offset similar to what yours looks like now, hoping it would give more travel and rotation of the star during upshifts. It didn't help, lol. Eventually, I will probably set it back to centered. I just need to be very deliberate when making that 1st to 2nd shift.
Click to expand...
I’ll try to Center it and see if it helps. Do you know if I pull the c-clip on the LHS, does the shift shaft pull straight out of the RHS or will internal components come loose?
 
It pulls straight out... for (somewhat) easy replacement when it gets bent or the splines get boogered up.
 
Jim said:
It pulls straight out... for (somewhat) easy replacement when it gets bent or the splines get boogered up.
Click to expand...
Ok thanks. I think I’ll also “adjust“ the lever to be somewhat centered inside the star wheel assembly. Going to grab my manual about the other recommended centering.
 
I'm with Jim on the centering part

I also think that is worth inspecting perhaps that is what you are referring to in # 10
So that the horizontal part with the shark fins is not to far out to the side
like below when in its normal operation position.
I got one brand new axle that was not with a 90 degree angle had to put it in the vice hitting it

I myself would most likely replace the springs ..once so far in there
If I recall right it was not so expensive, $ 10 --$ 15 saving the hassle do it over again
in the near future



1646950827690.png
 
Jan_P said:
I'm with Jim on the centering part

I also think that is worth inspecting perhaps that is what you are referring to in # 10
So that the horizontal part with the shark fins is not to far out to the side
like below when in its normal operation position.
I got one brand new axle that was not with a 90 degree angle had to put it in the vice hitting it

I myself would most likely replace the springs ..once so far in there
If I recall right it was not so expensive, $ 10 --$ 15 saving the hassle do it over again
in the near future



View attachment 209436
Click to expand...
I went ahead and centered the “shark fin” lever in both directions to the star wheel. Had to remove the shifter, put it in a vise and give it a slight bend. Didnt have time to get a spring. Will test tomorrow with fingers crossed. Not while I’m riding though. Lol.
 
You don't center the "claw" on the star wheel by bending things, you use the adjuster screw shown in post 4, pic 3. It's a concentric type screw and turning it moves the shift arm (and "claw") right or left.
 
bosco659 said:
Anyone have anymore thoughts on this before I put it all back together? Would prefer that I don’t have to take it apart again. Lol.
Click to expand...

Well if it is adjusted ..and springs are OK I would shift it many times observing if it seems to hook and move OK
Without missing
it almost worked from the start .. and after adjusting and shift through ca ( about ) 10 times.
With no problems ..
I would sleep well assuming no problems there. Done a good job.

btw --- No metal in the oil and Filers ???
 
Jan_P said:
Well if it is adjusted ..and springs are OK I would shift it many times observing if it seems to hook and move OK
Without missing
it almost worked from the start .. and after adjusting and shift through ca ( about ) 10 times.
With no problems ..
I would sleep well assuming no problems there. Done a good job.

btw --- No metal in the oil and Filers ???
Click to expand...
Thx Jan. No there is no metal in the filters.
 
5twins said:
You don't center the "claw" on the star wheel by bending things, you use the adjuster screw shown in post 4, pic 3. It's a concentric type screw and turning it moves the shift arm (and "claw") right or left.
Click to expand...
Yes I adjusted it that way to center. I tweaked the arm to sit Center of the star wheel and shifter drum shaft.
 

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