Topic: First Bike! 1972 CB500/4

[sammermpc]

Hello,

I just picked up my first bike a couple of weeks ago -- a 1972 CB500/4 in pretty good condition. I went up with a buddy who checked it out with me. It started straight-up, switch and kick, and I took it for a ride or two around town. PO was a serious guy and did some work on it -- carbs, pressure, etc. He did say the oil was worth replacing, as it was old, though clean.

Anyhow -- it worked great, except that the left rear blinker wouldn't come on and the action was funky.

OK! No problem. I'm not a mechanic, but I know my way around electronics, so I fiddled with the grounding in the fixture, and (this is the part that got me into trouble), opened up the grip and repaired the action on the clicker.

Of course, like a fool, I ignored the clutch adjustment. After putting back together, the clutch wouldn't disengage, so it stalled whenever I went back into 1st. I tried various versions of the clutch adjustment online, including the routine followed in the manual. I know there are a bunch of versions, but basically, something like this:

1. Turn the cable adjusters at the handlebar side and the clutch-side all the way in.
2. Unscrew the lock-nut and turn the adjuster on the clutch cover all the way, than back off a few mm.
3. Turn in engine-side adjuster until about 1/2 - 3/4" free play on the clutch.
4. Do some fine adjustment on the grip.

Hasn't made much of a difference, and when it's up on the center stand in first w/ the clutch pulled, the wheel is turning pretty good. It'll stall if I bring it down with the clutch pulled.

Since all of that fiddling, I think I've messed more things up. It's way trickier to start the bike than it used to be. I could only get it going with the choke all the way OPEN (that is pointed down), and kicking it pretty good while in neutral (w/o pulling the clutch). Not sure why that would be. In the process of all of this, I've discharged the battery a couple of times (it's new), which slows me down as well. While it always idled pretty low, now it'll only idle with the choke all the way open, and the RPMs will fluctuate pretty high (3k+). I fiddled with the idle screw at some point, to try and stop it from idling too low, and that could be a problem, I am sure. What'll happen is that the RPMs will spike up to 4k+ (maybe because of the screw?), and then as I CLOSE the choke, they'll gradually go down and no amount of throttle will keep it from dying. If I open it back up, it'll stay going, but at pretty high RPMs. Isn't that the reverse of expected behavior? I may have made it super-hot by idling it so high with the choke open.

Anyhow -- this is probably a case of someone without enough know-how messing with too many things -- and I'd like to just mess it back! I'm happy with learning the basics of this (I've read a ton of posts on here), but I want to stop doing things the wrong-way around.

I know I need to go through the 3k maintenance schedule, as well, but thought I'd just toss out what I'm working with here, if you've got some pointers.

Thanks for any help! I'm sure I'll be around here for awhile

[Kenzo1979]

You're not supposed to turn the adjuster on the engine case cover "ALL THE WAY" then back off.  You're supposed to turn that adjuster only until it MEETS RESISTANCE.  Then you back it off 1/4 of a turn.  So that's the clutch adjustment.

As for the idling, You need to make sure your carbs are clean, floats are set properly (22mm) and bench sync.  Set your air mix screws out about 1 1/2 to 1 3/4 turns.  You need to set your points gaps and do your timing.  Air box, I'm assuming stock, clean and free of debris.  Your Fuel tank breather hole must be clear.  Petcock and fuel tank clean and free of debris.  Check for air leaks in the intake.  Run the bike.  If all is well, sync the carbs with gauges.

[sammermpc]

Thanks for this -- yah, I've been doing the adjustment as you described, not as I wrote it. By all the way, I mean, until it hits good resistance. I've been using a quarter or a fat screwdriver w/o much force, so that feels ok, as far as I know. All the same, I've tried a bunch of different settings (1/8 turn back-off, etc.), and the clutch doesn't disengage all that well, though I can shift into neutral easily. I'll keep playing with it. It was working fine initially, so I think I should be able to get it fixed up.

The more I play with it, the more issues I think there are with the carbs (assuming I get the clutch issue resolved).

I started it up this morning with the choke closed -- it started right up -- and then gradually eased the choke open, and it revs up really fast to 3-4k. I can kind've modulate the idle by closing the choke again, which slows it down, but if I close it too much, it dies. It's not responsive to the throttle at all, really, when the choke is open. I guess because the engine is already racing? Gets pretty hot, too.

I assume this all points towards basic carb maintenance, which I suppose I'll have to learn . This is a newb question, I know, but I haven't seen it addressed directly: can all the carb work be done on the bike itself, or I do I need to remove the assembly?

[K3Owner]

sammer....

You need to put the call out to any local CB'er and invite him over for some BBQ and beer. After a day of messing with that CB and haveing all your questions answered by example, you'll be semi-pro. I didn't know much about an engine at 16 but was converting 6 to 8 and autos to manuals by 19. Hondas are a blast to work on...

I heard you messed with the idle screw and if it races with the choke open, can't the idle be lowered at the screw? Have to ask this since it was good when you started. You were in the switches but the throttle cable is on the other side than the blinkers so we may be able to rule that adjustment out?

I don't understand the clutch issue. You removed all slack and it still won't engage but it was fine before you started. If there is almost immediate resistance in the lever after a bit of play on initial squeeze and it continues with tension to full pull, the clutch is engaging. I don't expect something broke in there...

As I said, it may be onsite guru time. I'd be there if I could but y'all are too far north for me.

[sammermpc]

Thanks for the offer, K3. I'm sure I'll make some good contacts around here, too.

Anyhow -- some good news! I got it going and took a ride this morning. Essentially, I think a lot of what I was experiencing was a basic unfamiliarity with the operation of the bike, and the trickiness of operating a forty-year old machine.

I carefully adjusted the clutch once more -- according to the instructions given -- and though it still jerks me a little bit when I hold the clutch down and shift into first, it definitely is disengaging. From what I understand, this is fairly common.

After reading through a number of threads, its clear that warming up the CB500/4 is a bit of an art. I was using the choke wrong, the first time around, so this time I did it right, I think.

While on the center-stand, I turned it on with the choke closed -- it needs a bit of throttle to kick-up nicely -- and let it run for a bit. I gradually eased the choke open while giving it throttle (I used the thumbscrew under the grip), and it didn't race off and seemed pretty level. I gave it throttle for awhile till it was pretty warm, and then took off the thumbscrew and adjusted the idle screw, till it seemed pretty stable in the 1k - 2k range.

Anyhow -- I think there's a lot more to be done, but my initial fears of totally mangling things seem to have been recovered. I can't wait to ride! There's so much good information here.

A related question: there's talk of Hondaman's clutch adjustment calibration procedure -- but after reading through many, many threads, I can't seem to find it. Any thoughts?

[Kenzo1979]

Have you had the clutch cover open at some point.  If not maybe the PO did.  I'm just wondering if you might be missing the ball bearing that pushes against the lifter rod (#18, far left in this parts pic).  If so, just get another bearing and use a wad of grease to keep it in place, then reassemble.

[sammermpc]

Yah, I'm going to open up the cover and take a look soon. The screws are really seized up (and they're really soft), so I think I need to find an impact hammer. I'll let you know.

Another ride today. I have it idling really high -- 2k - 3k -- is that something to worry about? When I adjust it down, it feels like it might stall. Pretty hard to start, too, I had to kick it over instead of using the electric starter, even though it was hot. These are the little parts of having a bike like this, though, I guess. Feels great on the road. The clutch is working nicely.

[Kenzo1979]

Yes 2-3k rpm is a very high idle.  Not good.  You gotta get this thing adjusted right before you start riding it or you're gonna have more problems.  Definitely use an manual impact driver to remove those screws.  Have patience.  And if you strip out the screw head, tap a socket (one that is slightly smaller than the screw head) onto the screwhead and use the impact.

[sammermpc]

Hm, good to know. Is it possible that the high-idle is just masking the lousy clutch -- and that'll stall out once I get it down?

I think I definitely need to deal with the carbs, because some of the pipes are way hotter than others. One is too hot to touch, while another is just warm. I'm going to try and meet up with some local folks, who might help me take a look and give me the basics of figuring things out.

[Bankerdanny]

A little throttle when cold is normal. Only the 77-78 K bikes with the PD series carbs have fast idle cams. So when it's cold you will need to use the throttle to keep the RPM's up a bit as it warms up.

[bjbuchanan]

Set the clutch on a warm bike, it will be a little bit  better for what you need. Unless you have a later bike, which you don't, with fast idle cams then you gotta learn the machine and work the throttle to get it nice and warm. Warm it up and set the clutch. Loosen up til wiggly and annoying any clutch bolts at engine and handle and then turn lightly til ANY resistance is felt. Some bikes it is more obvious, others it is just some resistance to turning, not a definite clunk or hard spot.

Now turn back 1/4 turn and leave it be, lock up that adjustment nut. Now tighten up at the engine, and then tighten at the handlebar til it is just like 1/8 til 1/4 inch slop. I prefer 1/4 inch slop, it feels better for me. You should be good on a warm engine. This should fine first and neutral for you. If it ends up that you need more finesse and adjustment try to ride it how it is and warm it up, nice and hot from riding. Try adjusting in the same way, see how far you get