Topic: Transmission Noises - 1974 CB550

[joemcvw1951]

I have a noise that I think is coming from my clutch or my transmission. It is a sort of metallic whirring or rubbing is the best I can describe it. I only hear the noise in nuetral both when the clutch is out or in, the noise goes away completely and immediately as soon as the bike is in gear,

Any idea what might be causing this ??

[ekpent]

Bet a dollar someone asks what kind/model of bike 

[joemcvw1951]

Good bet, I amended the topic to include that, thxs

[Hannibal Smith]

It is the kickstart engagement gear. I went through this EXACT issue with my '74 CB550.

There is a stamped steel part that has a built in ramp. This ramp acts on an engagement cylinder, and pulls it away from the gear that is nearest to the outside of the right case.

When in working order, the ramp disengages the two mating assemblies when the kicker arm is in the "up" position. If the ramp gets bent, the gap is decreased and the two will rub their unidirectional teeth. That is that awful sound you hear. If you continue to use the kickstart it will only get worse.

You may think you can fix it by grinding the forward stop lug on the kicker shaft after removing the clutch cover only. It doesn't work. Trust me. You will still have not fixed the bent ramp.

You will need to get another ramp (they are cheap) and they usually come as a kicker shaft assembly (ebay etc.) Many used kicker shafts are bent so be aware.

I hate to say it, but you are going to have to pull the cases apart to fix it properly. You cannot access it if you remove the pan.

What causes this? 80% comes from releasing the lever and letting it fly upwards, and 20% from kicking too hard and fast. I am just using these percentages to illustrate my point.

When you kick, push the kicker arm down a few inches slowly, this allows the ramp to release without loading the engagement cylinder and fighting itself (bending the ramp). When you release, don't just let it pop up, ride it up with your boot.

The stamped ramp is wimpy, and Honda obviously didn't plan for it to be a primary way to start the bike. My bike is kick only, and when I was having ignition trouble, I kicked it too hard and fast all day one day, and actually heard a "pop" as it bent and impacted the ramp.

I replaced my ramp assembly, kick mellow now, and she is working great. If your bike is tuned right, you should be able to start it with baby kicks, just a quick little push will do the trick.

If you pull your clutch and rotate the basket's shaft you will hear the ratchet sound. I am 110% sure this is your issue.It sucks busting the bottom end apart, but it has to be done if you want to get rid of that sound.

[joemcvw1951]

Thanks, weird part is that I never use my kick starter :-)

[Hannibal Smith]

Thanks, weird part is that I never use my kick starter :-)

It was already damaged, and that sound will not go away. It might not get any louder if you don't use the kicker, but it is two sets of unidirectional teeth skipping over one another. The gears are heat treated so it's not like you are creating tons of metal filings as they whir happily away, but it drove me nuts. As soon as I identified the problem, I had to fix it.

In your manual (Clymer) on page 100 you will see the kickstart assembly. The stuff I am talking about are the (1)Kickstart gear, (4)Ratchet, and (7)Stop. The Stop is what is bent and the cause of your noise.

Forgot to add- I know that this is your issue, but there is another way to confirm.

Pull the clutch assembly, and rotate the shaft, you will hear the clicking. Pull the kicker down 2-3 inches, and the same clicking will be louder. I forget how many clicks per revolution, but it will be HALF the amount of teeth on the ratchet per revolution of the clutch shaft. This is how I knew for a FACT it was my kickstart, even though I tried to kid myself it was something easier to get to!

Example- If your ratchet has 22 teeth, you will hear 11 clicks per revolution. Presto! It's the kickstart making all that noise.

[joemcvw1951]

Thank you, I really appreciate the time you have taken to go through the issue and to give me a way I can confirm the problem. Of course I'm in denial !!

A little more information.

I had just had the carbs rebuilt but the guy didn't have the guages to do a vacuum synch, started hearing the noise about 20 miles later and I never used the kick starter. Also , I never used the kick starter in advance of the noise starting and the noise isn't apparent as soon as I start the bike, it starts up after a couple minutes when it warms up.

[Hannibal Smith]

Thank you, I really appreciate the time you have taken to go through the issue and to give me a way I can confirm the problem. Of course I'm in denial !!

A little more information.


I had just had the carbs rebuilt but the guy didn't have the guages to do a vacuum synch, started hearing the noise about 20 miles later and I never used the kick starter. Also , I never used the kick starter in advance of the noise starting and the noise isn't apparent as soon as I start the bike, it starts up after a couple minutes when it warms up.

My noise didn't start being audible until about 500 miles later. I just kinda noticed it one day. It got louder from there.

[TwoTired]

Thank you, I really appreciate the time you have taken to go through the issue and to give me a way I can confirm the problem. Of course I'm in denial !!

A little more information.


I had just had the carbs rebuilt but the guy didn't have the guages to do a vacuum synch, started hearing the noise about 20 miles later and I never used the kick starter. Also , I never used the kick starter in advance of the noise starting and the noise isn't apparent as soon as I start the bike, it starts up after a couple minutes when it warms up.

My noise didn't start being audible until about 500 miles later. I just kinda noticed it one day. It got louder from there.

Did the noise go away when you put it in gear?  The O.P.'s does, from all reports.  I don't know if the kick start mechanism would care about being in gear or not, regarding a noise issue.

Pretty hard to diagnose a noise in a text medium, imo.  For me, I think I actually need to hear it.

Describe the sound a bell makes, for example.

[Hannibal Smith]

Thank you, I really appreciate the time you have taken to go through the issue and to give me a way I can confirm the problem. Of course I'm in denial !!

A little more information.


I had just had the carbs rebuilt but the guy didn't have the guages to do a vacuum synch, started hearing the noise about 20 miles later and I never used the kick starter. Also , I never used the kick starter in advance of the noise starting and the noise isn't apparent as soon as I start the bike, it starts up after a couple minutes when it warms up.

My noise didn't start being audible until about 500 miles later. I just kinda noticed it one day. It got louder from there.

Did the noise go away when you put it in gear?  The O.P.'s does, from all reports.  I don't know if the kick start mechanism would care about being in gear or not, regarding a noise issue.

Pretty hard to diagnose a noise in a text medium, imo.  For me, I think I actually need to hear it.

Describe the sound a bell makes, for example.

Yes, it goes away when in gear (at least you don't hear it anymore). When the kicker assembly is good to go you will hear nothing when you rotate the clutch shaft. When the "Stop" ramp is bent you will hear the ratchet sound, kicker all the way up, and it will get louder, click for click when the arm is depressed slightly.
 
The check is easy. If you hear a ratcheting when the kicker is all the way up when you spin the clutch shaft (remove the basket), your ratchet and kickstart drive gear are touching when they should be apart (retracted). You will hear that awful noise. The Stop ramp is bent.

As stated above, the clicks will be half the number of ratchet teeth, per revolution of the clutch shaft. It is what it is. When I counted the clicks, I went "Noooooooooooooo!!"

I actually machined a custom Stop assembly from a billet of heat-treated 4140, but that is probably out of the standard realm of fixes. Mine will never bend now. And yes, that fixed it.

[Hannibal Smith]

Forgot to add. The stock Stop is heat treated, and will probably fracture if you try to bend it back.

Because the Stop ramp coincides with the Ratchet ramp, it only has to be bent a teeny bit and the problem is compounded. The stop ramp has no support, it is basically "floating" in the case, it is only held against rotation and located on the kicker shaft. If the "U" of the ramp doesn't have parallel sides it is bent.

Kicker assemblies run $25 or so on Ebay. When you look at the picture, see if the Stop ramp looks bent "down". I can tell in an instant now.

[b1jackson]

Reviving this thread from the dead.  It looks like I have the exact issue in a 74 cb550 but with some effort, looks like I am able to pull the guts out the bottom of the engine. Did it this AM on a donor engine anyway.