S 90 grinding into 2nd gear
- Thread starter Catchalot
- Start date
Unless it's your shifting technique, i.e. how you modulate gear changes via throttle & clutch application, I'd suspect worn shift pins...possibly forks & drum, also. The pins determine lateral movement & positioning of the gears. If there's slack (excessive clearance) between them & the groove in the drum, the gears won't move fully into position quickly enough to avoid unwanted tooth contact. Same thing could happen if the forks are too loose, wobbling, on the drum.
Thanks for the reply. Is there no other way then but to split the cases ? Sounds like humongous job! Maybe I should just start off in 2nd gear ?? Although I would like to get it fixed! Any videos of the fix available?
I'm not an S90 expert so correct me if I'm wrong. As I recall, they're all manual, i.e. hand clutch. Thus, there's not much to do, externally, other than making sure the clutch & cable are properly adjusted. And, since it only does this on the 1-2 upshift, that kind of eliminates the clutch as the problem. Still, I'd at least attempt adjusting the clutch by decreasing the freeplay in the bellcrank assembly...and the cable.
From a dead stop, engine running, does the bike lurch at all when shifting from neutral into 1st gear? If the answer is "yes" then there might be hope for a clutch adjustment. If the answer is "no", the problem lives inside the engine somewhere...and you'd then start by pulling the clutch cover, to inspect the shift linkage/star/arm/stopper, etc. It is possible that the shift star has come loose and only affects the one gear change but...that's a longshot.
From a dead stop, engine running, does the bike lurch at all when shifting from neutral into 1st gear? If the answer is "yes" then there might be hope for a clutch adjustment. If the answer is "no", the problem lives inside the engine somewhere...and you'd then start by pulling the clutch cover, to inspect the shift linkage/star/arm/stopper, etc. It is possible that the shift star has come loose and only affects the one gear change but...that's a longshot.
None of these motors bench shift quite the same as they do while riding.
Seems worth trying to adjust the clutch, since you do get a slight lurch. Honestly, I don't know if this motor has a clutch adjuster or if it's all done via cable adjustment. If there is one on the motor...as there is on a CT70H, SL70, CL70, et al, then I'd try tightening-up the clearance, tweaking the cable freeplay then going for a test ride.
Seems worth trying to adjust the clutch, since you do get a slight lurch. Honestly, I don't know if this motor has a clutch adjuster or if it's all done via cable adjustment. If there is one on the motor...as there is on a CT70H, SL70, CL70, et al, then I'd try tightening-up the clearance, tweaking the cable freeplay then going for a test ride.
Thanks again. I have the right side cover off. The end of the shifting drum has three removable pins. Only one pin protrudes the other two are set back. The shift the star and the washer have holes in them that appear that one of the pins should go into. None of the pins are long enough to engage this. Also the Star looks nothing like the manual pictures. Thanks for any enlightenment.
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That's very similar to the Z50/CT70. The longer pin positively locates the star, in it's correct position. The large washer helps guide the shifter arm; some of the z50-based transmissions have this washer, others don't...no noticeable effect on shifting,
Check the pins for wear, at the locations they contact the shifter arm...and...check the shifter arm for wear. I'd be shocked if you find any. The pins are a very hard alloy steel, the shifter arm doesn't do much.
FYI...to be clear, I'd NOT expect to find anything worn here. It's the pins that locate the shift forks, inside the cases, that may be worn...along with the forks. for now, we're starting with the easy stuff, hoping that the problem will be found & correctable without having to split the cases.
Check the pins for wear, at the locations they contact the shifter arm...and...check the shifter arm for wear. I'd be shocked if you find any. The pins are a very hard alloy steel, the shifter arm doesn't do much.
FYI...to be clear, I'd NOT expect to find anything worn here. It's the pins that locate the shift forks, inside the cases, that may be worn...along with the forks. for now, we're starting with the easy stuff, hoping that the problem will be found & correctable without having to split the cases.
I dunno about that one...sounds like a bad idea to me. Honda didn't include any "extra parts" AFAIK. How is it even possible for that long pin to not engage the locating hole in the star? Look at the shadow left behind, it was positioned where it needed to be.
FYI, the star only helps to locate the shift drum. It's the pins that transmit the rotational force.
FYI, the star only helps to locate the shift drum. It's the pins that transmit the rotational force.
I could certainly put something in the hole behind the pin to increase its length. Do you think that would be better than eliminating the washer? I disassembled an old motor I had and there was no washer on that shifting drum between the star & drum !! Don’t know if either attempt will correct the 1st to 2nd grinding issue? Thank you very much for your input. It’s been a great help and hopefully I won’t have to split the cases
kirrbby
Well-Known Member
In post #8...
Pic #1 is the end of the shift drum?? Only one pin protruding? The shift arm must tuck behind that flat end somewhere??
The shift arm catches on those pins to spin the drum and change gears. So my question is...does the shift lever arm catch all three pins, and spin the drum??
Pic #4 is the Xtra washer that you mentioned?
Pic #1 is the end of the shift drum?? Only one pin protruding? The shift arm must tuck behind that flat end somewhere??
The shift arm catches on those pins to spin the drum and change gears. So my question is...does the shift lever arm catch all three pins, and spin the drum??
Pic #4 is the Xtra washer that you mentioned?
kirrbby
Well-Known Member
Ah ya. Looking at some parts on eBay. I see how the drum looks. Now it makes sense that only one pin should protrude.
https://www.ebay.com/itm/Honda-CS90...250291&hash=item3cbb2e029f:g:ZJ4AAOxyhlJRcS-n
https://www.ebay.com/itm/Honda-CS90...250291&hash=item3cbb2e029f:g:ZJ4AAOxyhlJRcS-n
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kirrbby
Well-Known Member
Ya, that could definitely cause a problem.
I see no reason for that Xtra washer either. Leave it out, but hang on to it.
Might be a good idea to replace the pin that protrudes, if it looks TOO worn...too worn to do it's job.
Or, like racerx said, you could put something into the hole behind it, then dress the end.
You might even be able to simply spin it. Put the worn end in the hole, and the opposite end is probably in good shape still, having lived it's life in the hole. lol
I see no reason for that Xtra washer either. Leave it out, but hang on to it.
Might be a good idea to replace the pin that protrudes, if it looks TOO worn...too worn to do it's job.
Or, like racerx said, you could put something into the hole behind it, then dress the end.
You might even be able to simply spin it. Put the worn end in the hole, and the opposite end is probably in good shape still, having lived it's life in the hole. lol
