72 CB350 Can't shift out of first

Hi,

Long time lurker, first time poster. I'm running into a problem that I just can't get past.

After a recent top end rebuild due to oil starvation, I'm unable to shift the bike higher than first gear. At first I thought it was due to the shift lever linkage, so I replaced the original shift lever with a simple one that attaches directly to the shift spindle. Although it removed the slop in the lever, it didn't allow shifting out of first. So, I tore open the right side, removed the clutch basket, etc to take a look at the stopper and the drum cam that can come loose according to other posts I've read. Everything was secure and I was easily able to shift through the gears by turning the screw on the top of the star-shaped drum cam. So, while I was in there, I took the mechanism apart and gave everything a thorough cleaning and reassembled. At this point I was also able to shift through all gears using the shifter and rotating the rear wheel. So, problem solved, I thought.

After buttoning everything up on the right side, I gave shifting a try, and I was back to being stuck between neutral and first. After drying my tears of frustration, I removed the side cover; tried the lever and was able to move through the gears. Put the side cover back on and just finger tightened the bolts - still success! Torqued down the bolts - problem came back. So, it looks like something is binding the shifting mechanism behind the clutch basket.

I have noticed that there is approx. 3mm of lateral play in the spindle shaft. In other words, from the left side of the bike, I can move the shaft in and out a few mm. which can mess up it's alignment with the drum. However, from looking at the parts fiche, there doesn't seem to be anything that actually keeps the spindle shaft in place other than the pressure from right side cover.

I hope I've described this adequately. Thanks for your help.

Steve

Are you trying to shift gears without the bike running or spinning the rear wheel?


You need to have the bikes' final drive moving in most instances to shift gears.

I'm manually turning the rear wheel while the bike is on its center stand.

If it is shifting normally with the cover off, but will not shift with the cover on, I would presume your problem is in the cover somewhere. Since there is some lateral play in the shift shaft, be sure that it is fully in place and engaged when you put the cover on. It sounds like maybe the shaft is getting pulled out, and then when you put the cover on it is binding up.

Actually, I can reproduce this manually. If I pull on the shift shaft from the left hand side of the bike, I can cause the pawls attached to the end of the shaft to come out of alignment with the drum, which prevents any shifting above 1st. However, if I push on the shaft from the left hand side, the alignment between pawls and drum remains correct and shifting occurs normally.

I've inspected the interior of the side cover and I can't see any problems with it. I'm thinking I could just pop a shim washer behind the shaft to remove the lateral play. Are there any obvious dangers with trying this as a solution?

It's the shift fork itself. I ran into the same issue on my SL350 build. Take the shift fork out and grind down a bit of the metal rubbing on the clutch cover. Aftermarket shift forks tend to be a bit too long on the part that bends like an L
On this photo follow the small spring down and see where the shift bracket bends towards the clutch cover.

You should be able to look at the clutch cover and see where the shift fork is rubbing on it.

I just removed a few mm of metal off mine and problem was solved.




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That's awesome xulf13! I'll try that this weekend and let you guys know how it goes.

Update:

So, I took xulf13's advice and broke out the dremel. I shaved about 2-3 mm off of the tab that pokes out from the spindle and makes contact with the side cover. As he predicted, I could actually see a shiny spot on the aluminum where the spindle was wearing on the side cover. To remove all lateral movement on the spindle, I also fitted a compression spring and a shaft collar between the left shifter cover and the case. This keeps the spindle linkage correctly aligned with the drum by applying a constant pressure to the shaft. I got this idea from an ATV forum where a guy was having a similar problem.

Went for a 30 minute test ride last night and shifting was fine the entire time, so I'm cautiously optimistic that the problem has been solved.

A big thanks to you guys for all your help - especially xulf13. I'll update the thread again once I'm certain that things are okay.

I'm glad that worked out Wildboar. And I'm also glad you replied and gave back some feedback. A lot of people ask for help, they get it and disappear. Don't be a stranger. All the best and Ride safe!


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