Finished up my 2nd H model rebuild, and this one has a quirky 2nd to 3rd gearshift. Both rebuilds I went with the 88cc cylinder, HD clutch,new crank, hotter cam, with 1down 3 up conversion drum. I re used the original shift forks on both bikes due to the fact that the forks supplied with the conversion drums looked very poor quality at best. The originals appeared to be a way better bet. Shifting the transmission on the bench it did show signs of a problem. when shifting 1-2 no problem, when shifting 2-3 it would hang up. 3-4 no problem. I pulled it all apart, inspected everything to confirm all the c-clips and splined washers were in place gears looked good and all was good. What I did see happening was that two of the gears with the fingers protruding would hit directly together not allowing a mesh causing a "neutral" situation between 2-3. It will down shift all gears perfectly. I figured shifting it on the bench without power was causing the problem, but test riding has an issue every so often where you have to almost shift it twice to get third gear. Whos got some thoughts?
CT70H transmission issue
- Thread starter Vitamin C
- Start date
I checked and rechecked the assembly, I even slept on it and went back at it the next day. I used the new pins with the conversion drum. At this point its either forks, a funny gear, or could a worn splined washer cause an issue?? they were all in place. This will drive me nuts, so I will probably have this back apart soon.
It would drive anyone nuts, I reckon. I'd go back in now, not later, before the rings have a chance to seat and you have to deal with that, too, following a teardown.
If you can post pix of the shift forks, that might help answer the question. Can't recall seeing a worn spline washer...EVER. "Funny gear", no idea what that might mean, unless someone played mix-and-match with tranny parts, or the drive dogs are worn out. Those, FYI, are tapered; torque locks them into place while you're riding. If/when the taper goes away, typically, they'll start jumping out of gear...IOW, that's the telltale sign of worn drive dogs.
I'm kinda wondering about the shift drum you used. BTW, these transmissions do not like to bench-shift. Spinning the primary shaft, via the driven gear, does help with bench shifting. Another test "trick" is using the shift drum fixing bolt, via 10mm socket, to shift gears (on the bench, you have to remove the plastic plug to access it; if you can get positive shifting, in both directions, through all 4-gears, that's a good sign. If not, it's a good indication that the problem is in the tranny itself.
If you can post pix of the shift forks, that might help answer the question. Can't recall seeing a worn spline washer...EVER. "Funny gear", no idea what that might mean, unless someone played mix-and-match with tranny parts, or the drive dogs are worn out. Those, FYI, are tapered; torque locks them into place while you're riding. If/when the taper goes away, typically, they'll start jumping out of gear...IOW, that's the telltale sign of worn drive dogs.
I'm kinda wondering about the shift drum you used. BTW, these transmissions do not like to bench-shift. Spinning the primary shaft, via the driven gear, does help with bench shifting. Another test "trick" is using the shift drum fixing bolt, via 10mm socket, to shift gears (on the bench, you have to remove the plastic plug to access it; if you can get positive shifting, in both directions, through all 4-gears, that's a good sign. If not, it's a good indication that the problem is in the tranny itself.
You said you replaced the drum for a new pattern. Is it a cheap drum? The cogs hitting each other on the bench sounds normal to me. Are you using an H model diagram to help reassembly. The 4speed transmission doesn’t have a thrust washer in every location the 3speed does. I know you slept on it but just asking again. I think RacerX is more qualified than I am, but I’d be suspect of the shift drum and associated parts.
Funny gear just meant worn, or well used. Someone's been in this case before, so that probably a clue. It doesn't jump out of gear, or struggle down shifting. just the 2-3 upshift. The shift drum was from DRATV and a cheap piece, but I used the new pins with original forks. The shift drum star and follower assembly are also cheap appearing but seem to work ok. I agree bench shifting isn't a true indication, that's why I went ahead with assembly. I can get pics of the forks, but if I go back in they are getting replaced.
yes the drum looks to be cheap, but it works fine in my first H model with the original forks assembled the same way. The cogs hitting each other seemed to be what was happening on the bench. they would hit directly head to head and not allow the mesh of gears, I assumed this was due to bench shifting and it wouldn't be a problem under power. they were not broken, chipped or damaged. I did note this bike did have the single thrust washer at the case where my first H did not, possibly a problem??
For what's it worth, I have been into 4-5 H engines and all of 'em had worn shift forks. Even most of the trannys I've seen on e-Bay have worn shift forks. Maybe you'll be lucky, but I have not been so fortunate. Here's a good thread that shows what to look for.
https://lilhonda.com/index.php?threads/hko-shifter-forks.20126/#post-152181
https://lilhonda.com/index.php?threads/hko-shifter-forks.20126/#post-152181
The rule of thumb is that there's always a thrust washer between a spinning (the bore is not splined, therefore it can spin on its shaft) gear and the C-clip that retains it. Non-spinning (splined bore, locked in place to its shaft) gears don't need, and should not have, thrust washers, since the C-clip isn't doing much than on, say, the kickstart shaft...no mechanical shear to be protected from.
I rode the bike today and did notice that if you shift with a light toe, it will shift smooth as silk every time. If you get aggressive it will miss the gear. I did go ahead and order two shift forks, some splined washers and both main and counter shafts. If I open this thing back up, ill replace what I can to solve the problem.
dirtbkr188
Active Member
That is correct, Dyson, as seen in the pic below from the service manual...electrolux said:
kirrbby
Well-Known Member
Ok, update on the shifting problem. Today the bikes back together, and shifting properly, here are my findings.
After splitting the case I decided to throw parts at it and replace what's available. Both main and counter shafts, all splined washers and snap rings, Honda shift forks. With bench shifting, no change, it would still hang up the 2-3 shift. Try #2, Sanded any rough spots on the shift drum, added a little tension to the spring that holds tension on the star wheel follower, still no change. Try #3, ordered a complete new 1 down 3 up shift drum, transferred the new forks and BINGO! My guess is that something just wasn't right with that first drum. It would start the shift and just hang up and not complete the shift. I'm assuming these different pattern drums are not Honda parts. By looking at the shift forks supplied with them, id guess china.
After splitting the case I decided to throw parts at it and replace what's available. Both main and counter shafts, all splined washers and snap rings, Honda shift forks. With bench shifting, no change, it would still hang up the 2-3 shift. Try #2, Sanded any rough spots on the shift drum, added a little tension to the spring that holds tension on the star wheel follower, still no change. Try #3, ordered a complete new 1 down 3 up shift drum, transferred the new forks and BINGO! My guess is that something just wasn't right with that first drum. It would start the shift and just hang up and not complete the shift. I'm assuming these different pattern drums are not Honda parts. By looking at the shift forks supplied with them, id guess china.