Topic: 1973 cb500 four.Trans wont shift

[tory b]

  I have a 1973 CB500 that I bought as a basket case and have been putting back together.
The PO said he disassembled to motor because of a top end noise,but he had ridin the bike prior to tear down.
Now that I have foolishly invested alot of time and money putting this bike back together,it runs and looks great,but it will not shift into first or second gear.
  The clutch works fine,and the shifter is not froze.It feels like it clicked in,but when you let out the clutch it just kinda grinds like its halfway in gear.Samething 1st or 2nd gear.
  I'm hoping I don't have to tear the motor all back apart and split the case.Any ideas on a good place to start looking before I do that?

[JBMorse]

I would check the shift linkage mechanism and make sure everything is sound.  On my bike, the bolt that holds all that together, behind the clutch I guess ( I had a mechanic do this because I was on the road) had worked loose and so the bike wouldn't go into 1st and maybe 2nd. 
It's an easy fix that's worth looking into before you tear into the engine. 
If that's not the problem than you may have bad gear selector forks.  You do have to split the cases to get to those, but if I recall correctly  you can split this engine without taking the head or cylinder off.  You'd just work from underneath I guess.  Hopefully some experts will be able to be more specific with this.

[Oddjob]

Try popping the oil pan off and removing the oil strainer, you should be able to see the gears then. I'd check you actually have some teeth on first and second gears, get someone to change the gears as you look at the 2 shafts and see if you can spot what's going wrong. It may be a simple fix but TBH it doesn't sound like it's going to be, I suspect a broken selector fork or stripped gears myself.

[pdxPope]

Does it shift OK when not running?

Does it shift into 3rd or 4th? or are you just having trouble w/ 1st & 2nd?

How do you know the clutch is working OK?


CB500 clutches are notoriously finicky and can be tricky to dial in. I would make SURE it isn't the clutch before tearing into the motor. Remove the L side cover and make sure the actuator arm is ok. Also, there is a little rod that the actuator arm pushes, it has a tendency to snap or 'misplace' it's ball bearing.


-JP

[Greggo]

I suggest checking the clutch lifter mechanism nestled into the left side front sprocket cover.  Four screws hold the cover on, and on the inside you'll find the lifter mechanism.  Check it for breakage, and grease it up while you're in there too.

Here's a great link I recommend for any 500/4 rider:

http://forums.sohc4.net/index.php?topic=14273.0

[tory b]

Does it shift OK when not running?

Does it shift into 3rd or 4th? or are you just having trouble w/ 1st & 2nd?

How do you know the clutch is working OK?


CB500 clutches are notoriously finicky and can be tricky to dial in. I would make SURE it isn't the clutch before tearing into the motor. Remove the L side cover and make sure the actuator arm is OK. Also, there is a little rod that the actuator arm pushes, it has a tendency to snap or 'misplace' it's ball bearing.


-JP

1)Makes no difference running or not.

2) No,It does not shift into any gear.Will go down slightly to what feels like 1st,and up to what feels like maybe second only partially,but not above.It also feels like a neutral below both if that makes any cents.

3) I am quit certain the clutch is working fine,When I initially got the motor together,before I had carbs and tank ready,the disc where stuck together.I pulled them all,cleaned and re-oiled them and it appears to be working fine.
When I pull the clutch in and try to put the bike in gear,first or second,it doesn't grind until I release the clutch.Also with the bike not running,I can spin the rear tire by hand and try to click it in gear,but it still don't go all the way.

  It almost feels like a false neutral below first ,
Neutral,Half of first,Neutral,Half of second.No farther.
For all I know its stuck between 4th and 5th.

[tory b]

  Can anyone conferm that I can split the case with out disassembling the top end?
Can I service anything through the oil pan,or just look?

[twinegar]

PM me for a PDF of the shop manual.

[bryanj]

With the engine out you can strip the bottom case off leaving the top alone BUT as you have to remove all the outer covers and the clutch its worth removing the clutch cover and clutch and carefully inspecting the operating mechanism as if this is not assembled corectly or a spring has broken you would get this problem

[tory b]

   I removed the clutch and basket today and everything looks good behind the clucth.
I guess the next step will be to remove the motor and go from there.

 With any luck another motor will fallout of the sky,but I will disect this one and see where it goes from there.