Topic: 1974 CB550K: My first bike project

[c5ho]

Hey all, I've been reading lots on this forum and first off, let me thank all of those that contribute with their wealth of knowledge!  I can't wait to learn more and get my bike running as well as I know it can.

First off, a bit of background:

The bike:
1974 CB550 K0 serial # 101xxxx. 
Mileage: 29,xxx
 
When I got the used vehicle history, there were a number of previous owners on it (about ten), so it was one of those bikes that has been passed around from rider to rider but it looks to have been taken care of.  The frame has been painted silver, there are clubman bars installed, and also a 4-to-1 exhaust, so it looks to have been a project bike at one point.  The previous owner had the tank and side covers painted to match a custom cafe style seat pan/seat.

About me
I'm in my 30s, and this is my first bike.  I got my motorcycle license probably about ten years ago but never ended up getting a bike.  Last fall, I finally decided to do it again and did a certification course and got my license again and recently purchased this bike.  I would say I'm pretty handy and mechanically inclined as I've worked on multiple cars including my own.  I'm willing and eager to learn!

Current state
When I got the bike, I was hoping it would be rideable without too much work and/or a complete rebuild, etc.  However, I knew that this was wishful thinking, especially with a bike over 40 years old.  That's okay though as I don't mind getting my hands dirty and learning how the bike works.  According to the previous owner, he had owned the bike and rode it for about four seasons.  He had it serviced by an older bike mechanic that apparently knew what he was doing. (Or he may have been the only guy willing to even touch it.)  When asked what he had done to it, I was told he only needed to do regular maintenance and had the front brake rebuilt.  When asked about the engine and carbs, he said that the bike always ran well so they were never rebuilt.  When I went to see the bike, I had a buddy test-ride it for me and he said everything seemed ok.  So then the bike was towed home. 






We didn't realize the petcock was in the "ON" position during the entire tow until we got home.  We had trouble starting it off the tow truck but we finally did in order to ride it into my underground parking garage.  After letting the bike sit for a few weeks (as I got busy), I charged up the battery and the bike started with some choke.  A few days later, I had a buddy (who has experience building bikes) came over to take a look at the bike and we couldn't get it started.  We felt the headers and they weren't all cold so he suggested I get new plugs.  When I pulled the plugs, they were very black and smelled of unburnt gasoline.  I then put in all new plugs and the bike fired up right away.

Here's where it get's more interesting.  I warmed up the bike for a while with choke (1/8 open) but found that it would not idle properly without choke, to the point that if it close the choke all the way, the bike would die.  I took the bike for a ride thinking that it would eventually warm-up, but the same thing happened when riding.  As soon as I stopped, the bike would not idle and would die.  The power was also not very smooth and unpredictable.  From what I remember, acceleration was very flat until the revs got higher. 

I checked the static timing and adjusted it to make sure it was set correctly.  Then when I tried to set the dynamic timing, I couldn't get it to quite lineup.  This was also difficult to do as I had to keep the choke open a bit just to get the bike to idle and not die, so it was probably idling at about 1500rpm.  After some reading, I came to the conclusion that I would take the carbs off the motor and give them a good cleaning/inspection.  Since they haven't been done in a few years, I thought it would be a good idea to do it and also it would give me a chance to learn about the bike.

So here we go.  The 022A carbs came off the bike relatively easily and initial stages of taking them apart has been pretty easy. That is, there hasn't been any seized screws or anything.  Someone has definitely been in the carbs before as some of the screws just seemed finger tight.






Float bowls look pretty good:


Honda carb rebuild kits with gaskets and O-rings:


Question here.  I know where the two gaskets go, and three of the O-rings for the float needle seat, main jet, and drain screw.  What are the larger ones for?  Is it for the fittings joining the carbs?

I found that my slow jet was a #38.  According to the service manual, this should actually be #40.  According to the factory technical specifications page that TwoTired has posted (thanks btw), the slow jet size for the K1 is #38.  Would this be at least partially the cause for my idling issues?

Additionally, when disassembling the throttle valve and jet needle assembly, I found cylinders #1 and #2 were missing the spacer with the conical end.  Is this an issue?  And if so, where would I find replacements:


I have lots more pictures to post but I'm mobile right now so I'll post them when I get home.  I wanted to post my initial progress here so I could see if I was at least going in the right direction.  Thanks in advance!

[Bankerdanny]

That looks like a good first CB. Not much to do but fresh gaskets and the basic 3000 mile tuneup and enjoy.

[calj737]

The first thing you need to buy is a set of JIS bits. The screws on your motor are not Phillips, they're JIS. And they're very different. As you examine your bike, you'll notice some are stripped out because a previous owner used a Phillips on them.

Those large "O-rings" appear to be bowl gaskets. Stick with what you have. And avoid replacing the stock needles and jets with aftermarket junk. You need to remove the emulsion tubes and be certain they're completely clear, and perform a Clear Tube level on the fuel for proper adjustment.

Take a little time and verify that the intake boots are supple and the clamps are tight when you reinstall the carbs. That helps avoid any leaks.

[Gman]

C5ho,
Congrats on grabbing what looks to be a bike in good nick.  And, smart to take the certification course.  Having a license and knowing how to ride are two things - sometimes they seem to be mutually exclusive. 

Check with member Harisluv re: that cone shaped spacer - he's the carb go to guy on the forum.  If not, I probably have spares somewhere, but might take some hunting.  Let me know. 

Peace,
G

[Stev-o]

If your bike will not idle, the slow jets may be plugged.  Did you try turning the idle up?

Do you have a C5?

[c5ho]

That looks like a good first CB. Not much to do but fresh gaskets and the basic 3000 mile tuneup and enjoy.

When you say 3000 mile tuneup, are you referring to maintenance section of the service manual?

I've downloaded the Service Manual for CB500/550 (from http://forums.sohc4.net/?topic=17788.0) which lists these sections under Chapter 3 - Maintenance:

1. Tappet Adjustment
2. Carb Adjustment
3. Points and Ignition Timing Adjustment
4. Clutch Adjustment
5. Cam Chain Adjustment
6. Spark Plug Inspection
7. Engine Oil Change and Inspection
8. Oil Filter Service
9. Brake Inspection/Service
10. Air Cleaner Service
11. Drive Chain Inspection and Service
12. Battery Electrolyte Inspection
13. Front Fork Oil Replacement
14. Compression Pressure Check

The first thing you need to buy is a set of JIS bits. The screws on your motor are not Phillips, they're JIS. And they're very different. As you examine your bike, you'll notice some are stripped out because a previous owner used a Phillips on them.

Those large "O-rings" appear to be bowl gaskets. Stick with what you have. And avoid replacing the stock needles and jets with aftermarket junk. You need to remove the emulsion tubes and be certain they're completely clear, and perform a Clear Tube level on the fuel for proper adjustment.

Take a little time and verify that the intake boots are supple and the clamps are tight when you reinstall the carbs. That helps avoid any leaks.

Thanks Calj737.  I'll look into a set of JIS bits as well as check the boots while the carbs are currently off.  I realize the largest 'O-rings' are for the float bowls.  I was actually referring to the 'larger' rings of the smaller group.  The float bowl O-rings that came off actually look pretty good.  Ie, they are still soft and rubbery as opposed to feeling like hard plastic.  However, since I already have the carbs off and have bought the OEM Honda replacements, I figure I'll replace them now. 

I hadn't read about the Clear Tube test until just now so I will have to do a bit more research.  Is this test to confirm that the float level is set correctly?

C5ho,
Congrats on grabbing what looks to be a bike in good nick.  And, smart to take the certification course.  Having a license and knowing how to ride are two things - sometimes they seem to be mutually exclusive. 

Check with member Harisluv re: that cone shaped spacer - he's the carb go to guy on the forum.  If not, I probably have spares somewhere, but might take some hunting.  Let me know. 

Peace,
G

Will do.  I'm going to try to see if anyone local (I'm in Toronto, Canada) has them as well so that I can get these carbs back on the bike asap.

If your bike will not idle, the slow jets may be plugged.  Did you try turning the idle up?

Do you have a C5?

Are you referring to the idle adjustment screw?  I tried turning the idle screw in and closing the choke but this didn't seem to help.  I figured I should start from the beginning and make sure everything else was to spec before I use the idle adjustment screw to get me the rest of the way there.

As for C5, are you referring to the electronic ignition module?  I do not have a C5 and am on the stock points ignition.

[Stev-o]

Thought your forum name may be referring to a C5, otherwise known as a 5th Gen Corvette ['97-'04]. Guess not.

[calj737]

If your bike will not idle, the slow jets may be plugged.  Did you try turning the idle up?

Do you have a C5?

Are you referring to the idle adjustment screw?  I tried turning the idle screw in and closing the choke but this didn't seem to help.

No, he is not. He is referring to the internal slow jets within your carb. The idle screws are external. Part of a full and proper clean is the removal and absolute cleaning of these very small interior orifices. They clog rather easily when left unserviced.