Topic: Gearbox issues?!? I hope not...

[babyfood1217]

So I've noticed this problem a couple of times since I've had the bike (Fall '04), but never really thought of anything until recently.  Occasionally, and moreso in the more recent past, I have noticed that I have issues get the bike to engage first gear in a friendly manner.  For instance, say I am at a stoplight, or in my drive ready to pull out.  I pull in the clutch, kick down into first gear, and slowly ease on the throttle/off the clutch.  Instead of smoothly rolling away, the engine seems to rev up but not engage, then all of a sudden it will catch and the bike will either lurch forward a smidge then stall, or it will lurch forward, and I'll yank the clutch in before it stalls, only to have it happen a time or two more before the bike begins to roll.  Now, I would assume that this is either a gearbox issue, or a clutch issue.  I have not yet check over anything on the bike, so before I go wrenching away, I'll check out my shop manual, but right now I'm stumped.  Any ideas?  I seem to remember some people occasionally having issues with "dogs" (is that the right word?), but I thought that was just a issue that pertained to the engine slipping out of gear (which it occasionally does, but that's a different issue.)

Any thoughts?

-Chris

[Bodi]

The best case is a shift drum advance lever or detent problem. These bits are under the engine side cover so are relatively easy to look at and work on.
Less pleasant but IMO more likely would a bent shift fork and/or worn shift drum. The engine cases must be split to repair these problems.
Worn or broken gear dogs could be involved but would likely by caused by fork or drum problems rather than being the original fault.

[nomadwarmachine]

Before you dig into the cases you might also want to check the clutch plates to make they are not beyond the wear limit or otherwise buggered.  Sudden engagement does not sound like a worn clutch, but reving without moving does.  It is possible that something is gumming up the clutch release -- easy to check, easy to fix.

[CB750F2]

The fact that the motor is reving as you release the clutch suggests that the clutch is not engaging or first gear is not engaging. I would check clutch operation first because it is easy to do and fix - maybe a binding cable  - and then do what Bodi suggests. You should be able to tell if low gear has been selected - there is a bit of a "clunk" and the bike tends to want to move forward. Hope this helps, Pat from Australia.

[TwoTired]

It sounds like a clutch issue.  If it relates to what position your handle bars are in (turned right or left), then is it definately a cable issue.  Make sure your clutch cable is working smoothly, routed properly, isn't pinched somewhere, isn't worn or frayed, so it can't hang up upon release.

Next step would be to get into the clutch itself for inspection.

Cheers,

[Bodi]

Clutch is a possibility, but that would tend to cause trouble in every gear.

[TwoTired]

Clutch is a possibility, but that would tend to cause trouble in every gear.

I bought a CB550 with short bars. The PO had routed the clutch cable very badly and it has stress on it when the bars were turned to the left.  It would completely disengage the clutch without depressing the clutch lever!  It wasn't a problem in any gear but first because the bars were never turned enough while in upper gears for the clutch to disengage.  I found it hard to believe a rider would put up with this situation.  I wouldn't and a re-route of the cable cured the problem completely.

You never know what your going to find with these bikes.

Cheers,