Topic: HONDA TRANSMISSION QUESTION

[dramsell]

Trying to bring a 78 750F back to life after 20 years of sitting.  Got the motor to run, new wiring harness, rebuilt carbs and oil change.  When I put a clutch cable on it, it will not go anywhere when I put it in gear (although the wheels spun slowly while on centerstand and in gear). 

I observed the lever move inside the clutch housing and it will not turn over without the lever being pulled when in gear it just does not move.  Does this mean the tranny is junk or is there something I could have done wrong?

Any thoughts?

Dave R

[333]

I believe the 78 has a switch in the clutch lever perch that stops the starter if it is in gear.  Did it work before the cable change?  Inspection of the clutch itself may be in order to answer your question.

[mattcb350f]

Hmm. This post is a little confusing, Although there is something definately screwy with your tranny. Are you saying that with the engine running on the center stand and the transmission in (a) gear and clutch engaged, lever out, the wheel won't spin?
That would mean that the clutch isn't engaging.
Don't write off the tranny just yet, sounds like a clutch problem...
 Matt.

[CB750F2]

Dave, I think Matt is "on the money". I think that the clurch is not engaging with the clutch lever out. It may be partially engaged - enough to turn it slowly when on the centre stand but not enough to push the bike along when on the ground. I suggest that you get hold of a manual and and adjust the clutch cable as per the manual. This will ensure that you have some free play in the clutch lever. If this doesn't fix your problem you may have an internal clutch problem.
     The starter motor will not turn when the gearbox is not in neutral unless the clutch lever is pulled in. Hope this helps, Pat from Australia.

[dramsell]

Could someone please post this procedure-I do not have a good manual right now.

Thanks in advance.

Dave R

[Bob Wessner]

http://www.sohc4.us/forums/index.php?topic=26815.msg274270#msg274270

[dramsell]

Adjusted everything according to manual and when I started it up it moved a little but went nowhere.

I have a feeling the clutch plates are stuck together.

Dave

Thanks for all the help!

[ColinMc]

With the plates stuck together, won't it make the clutch always engaged? That's what happens to my Ducati if I wash it and let it sit after washing...open clutch cover lol.

[GammaFlat]

Adjusted everything according to manual and when I started it up it moved a little but went nowhere.

I have a feeling the clutch plates are stuck together.

Dave

Thanks for all the help!

Conversely, your plates sound stuck "apart".  I have the reverse problem when the bike sits.  The clutch will not disengage (stuck "together").  I'd remove the clutch cable (disconnect at the lever end) and put the bike in gear and try to rotate the real wheel (push the bike).  If it wants to turn the engine over (real hard to push), you are engaging and most likely have an aggressive tension on your clutch cable. 

[KB02]

Sitting for 20 years, huh? Yeah, it sounds like a clutch issue. Might have to pull it and clean it all up.

As for being stuck "apart" rather then together, the old KZ550 I used to have had the Clutch lever strapped to the handle bar when I got it. The PO had broken the clutch perch, and to work on the bike (it had a Safety switch) he had the clutch held open with packing straps (like whats on a box of printer paper). It must have sat that way for at least three years before I got it and cut the strap off. That clutch wanted to stick too.

[MRieck]

  If the clutch has been off/ or replaced there is a chance that the inner hub is not installed correctly. The inner hub should "lock" into the part that is inside the clutch (hard to explain). The cut outs on the inner hub for the steel discs should lock into a part inside the clutch( if you remove the inner hub, you should be able to see it on the other (very inside) side of the clutch plates). If it is not correctly installed, the inner hub will sit ON the part inside the clutch and not sit INSIDE (the cutouts on the inner hub sit inside the cut outs on the inner part) the part like it was designed.

 If it is not installed correctly, the inner hub wont squeeze the clutch plates together when the clutch cable is released. If you remove your clutch cover and the clutch plates have free play in them (wiggle-with out the cable pulled) then the hub is not aligned with the inner part. (sometimes the clutch cover will have scrapes on the back side from the 4 clutch spring bolts holding the clutch together)
   If you remove your inner hub (with the 4 bolts and springs) and turn it 90 degrees (or another 90 degrees, and so on- remove the inner hub and turn it so the stud for the clutch spring bolt is sitting on the next hole,etc) until the inner hub lines up with the very inner part of the clutch. When it is correct it should sit against the discs with out any spring pressure and shouldnt have any gap between the plates. You should see a difference in height when it has meshed with the inner part of the clutch.
 And adjust your cluch release mechanism and cable again.
  Try adjusting your clutch mechanism and cable first before tearing into it. It could be all that is needed.
 DG

I agree. I have seen this happen many times.

[Bodi]

If it kicks over with the clutch engaged but the kickstarter just fans with no cranking when the clutch is disengaged (lever pulled in) then the clutch is fine.
Do you actually have it in gear? This sounds most like a transmission in neutral, normally the rear wheel will turn if it's free when the engine is running.

[dramsell]

Bike will not start using electric start or kick while in gear UNLESS clutch lever is pulled in.  While in neutral it starts without touching the clutch lever.  Once started the bike makes the typical cb750 "clunk" into gear but won't move.

Dave R

[ColinMc]

I say just take the clutch cover off and have a look see...Whatever the problem is, it'll probably become apparent when have a physical look at the clutch.

[Bodi]

The kick start is via the transmission, ie the force goes through the clutch. So - with the clutch lever out - if you can kick the kickstarter and the engine crankshaft turns, the clutch is engaging reasonably well. With the clutch disengaged (lever pulled in) you should be able to kick the kickstarter down with very little resistance but the engine crankshaft will not be turned.
This just tests the clutch: if you can kick over the engine with the clutch lever out, but with the lever pulled in the kickstarter moves with no engine cranking... the clutch is pretty much OK and you won't learn anything by removing the clutch cover (except how to buy a new clutch cover gasket). If the kickstarter just moves freely regardless of the clutch lever, then the clutch is slipping and needs attention.
The electric starter drives the crankshaft directly. What you describe is normal - the motor will work when in neutral or with the clutch disengaged.
If the clutch seems fine I would remove the sump. First, you can see some of the transmission by looking in the resulting opening. Two, if the transmission has been damaged enough to cease transmitting, there may be some good sized pieces in the sump.
Also, try all the gears. The weakest link in the transmission is the drive dogs - they can just snap off if abused. If one set is gone, some gears will still work: ie you may lose first and third but still have second and fourth.

[Loudpipe]

Probably the drive dogs not engaging like Bodi said.  The friction inside the tranny between the layshaft and driveshaft will cause the rear wheel to spin slowly when no friction is applied to it, but you should be able to hold it in place with you hand while it's on the centerstand.

http://auto.howstuffworks.com/transmission2.htm

You can look at how the collar engages and see how the teeth could be broked off of it to cause the "clunk" as it moves forward or backward, but never really engages.