S 90 grinding into 2nd gear
- Thread starter Catchalot
- Start date
I’m going to re-assemble now. I will let you know the outcome. Thank you so much.
red69
Well-Known Member
By the way, I had that same problem on my S90. While I didn't completely cure the lurch upon 1st gear application, I managed to get rid of the grind into 2nd gear by adjusting the cable slack as racerx has suggested. I have about 6300 miles on mine without any case splitting.
Bob
Bob
red69
Well-Known Member
It may be the throttle slide sticking. I've had that happen with mine. There was a fix by Honda years ago on the Mikuni carb. It consisted of a slide that had a slightly smaller diameter (.02 mm-.03 mm) than the stock piece. If you have this carb, back off one of the mounting nuts on the carb flange a fairly small amount to see if it frees the slide. What I think happens is that uneven torque at the mounting point may distort the slide barrel.
If course if you have a Keihin, this will not apply and your problem may be with the throttle grip assembly. You will have to disassemble it to see if all is correct. Use some Lubriplate grease on assembly.
If course if you have a Keihin, this will not apply and your problem may be with the throttle grip assembly. You will have to disassemble it to see if all is correct. Use some Lubriplate grease on assembly.
I wasn't aware that this style of shift fork was used as early as the S90 era. This drum assembly looks sturdy, to say the least...right down to the threaded shift pin(!). Based on what I've seen with larger (100cc+) new-gen Honda engines, these forks are damn near bulletproof. If anything, the "weak link" in the chain is shift pin; since it's fixed (non-rotating) there's a chance of flat-spotting...which could cause problems. Consider, the floating pins are sometimes found worn and so evenly that you'd never realize they weren't machined with stepped-diameters...unless you've seen them new.
If the throttle sticks, then all bets are off. None of these transmissions will shift normally under load, even a partial load, and without coordinating throttle application.
Good idea to clean & lube the entire throttle operating assembly. Check cable action while you're at it; they can become arthritic over time. Might not hurt to either replace the return spring with a stiffer one, or give this one a gentle stretch. If the slide is binding inside the carb body, the high spots can be identified with Dykem, or black marker pen...then polished. Removing material from the slide is not a great idea but, a sticking throttle is worse.
kirrbby
Well-Known Member
Also be sure that you don't have a air leak in the intake. Good gaskets, sealing well, on BOTH ends of the intake tube.
If you suspect a small leak there, a small bead of heavy grease can sometimes help, and is super safe to use.
If you use some sort of sealer...be SURE not to over do it. Maybe even allow it to dry a while before you reassemble it.
If you suspect a small leak there, a small bead of heavy grease can sometimes help, and is super safe to use.
If you use some sort of sealer...be SURE not to over do it. Maybe even allow it to dry a while before you reassemble it.
Last edited:
I pulled off the funky “worm” gear throttle grip & the cable onlone snaps back nicely. Can’t get it to snap back when assembled !! Seems to be too much friction!!! I tried several different grips with same results. Lubed/cleaned/ Lubed again even filed some where it seemed too tight. Any ideas ?? I do believe this is a large contributor to my problem. Thanks
kirrbby
Well-Known Member
Pretty typical.
I've just gotten used to turning the throttle in both directions. Turn it forward, turn it back. If the cable is free, turning the throttle closed should...close the throttle. I also sometimes (usually) stretch the slide spring, carefully and evenly. If you can find a stiffer spring, with the same or close, dimensions, it might be worth the effort.
I've just gotten used to turning the throttle in both directions. Turn it forward, turn it back. If the cable is free, turning the throttle closed should...close the throttle. I also sometimes (usually) stretch the slide spring, carefully and evenly. If you can find a stiffer spring, with the same or close, dimensions, it might be worth the effort.
Isolate the sticking point. With CT70s, it's usually the vinyl grip cover...at least with the new OER. If the S90 uses the same throttle assembly, then we can offer some suggestions on how to free it up. When these bikes were new (first Honda I rode was a nearly-new S90) throttle return action was usually pretty good.
Funny thing about these internal twist grip throttle assemblies, they tend to improve with use. The helix & slide get smoother and the manufacturing quality was better 50 years ago. From what I've seen, it's mostly a matter of getting the 'throttle pipe" to move freely, with the smaller issue being the slide that holds the cable end. After cleaning out all of the old, sticky, grease, you want to use a thin grease, such as Lubriplate. It's, essentially, lightweight lithium grease, so the brand name doesn't make much difference. I've tried using bearing grease and, it's too thick.
All of the metal parts should be nicely broken-in, to each other. Clearances should be bigger than they were when new. So, unless there's rust inside, solvent cleaning, new grease (thin viscosity/high film strength) should work wonders. The only piece that may be fatigued is the return spring.
Funny thing about these internal twist grip throttle assemblies, they tend to improve with use. The helix & slide get smoother and the manufacturing quality was better 50 years ago. From what I've seen, it's mostly a matter of getting the 'throttle pipe" to move freely, with the smaller issue being the slide that holds the cable end. After cleaning out all of the old, sticky, grease, you want to use a thin grease, such as Lubriplate. It's, essentially, lightweight lithium grease, so the brand name doesn't make much difference. I've tried using bearing grease and, it's too thick.
All of the metal parts should be nicely broken-in, to each other. Clearances should be bigger than they were when new. So, unless there's rust inside, solvent cleaning, new grease (thin viscosity/high film strength) should work wonders. The only piece that may be fatigued is the return spring.
I’ve gone through the throttle grip assembly to no avail I can give it gas and return manually that’s not a problem. Now my issue is even though the carb slide snapps back quickly without the throttle assembly, just pulling the cable itself it’s the RPMs still don’t drop Imediately it’s a gradual slow down of the RPMs.? I have a little slack at top of carb. Starts right up. Bypassing throttle & just pulling up cable at carb, the rpm STILL decline slowly, even though the slid snaps back quickly !! ???
Only place would be “0” ring between carb & manifold.??(Besides head gasket)
Is there anything inside the carburetor that would cause an air leak? I cannot seem to get this to throttle down quickly. Thanks