My Turn

riverfever

riverfever

NAXJA Forum User
Location
Woodland Park, Colorado
I've been looking for a project for a long time. I don't really have the space, skills or tools to take on a car so I decided on a motorcycle. I looked and passed on several before settling on this one. I think it's a good starting point. It's a 1976 CB550K.



First step after I got it home was to start taking things off so I could do some cleaning and start checking that every bolt was torqued properly.



After a lot of steel wool and polish, the front end looks really good. I do not like that someone painted the forks and will eventually either take the time to sand and polish the legs or go black but that's way down the road.



Right now I am trying to gather the pieces to fit the stock airbox back into place versus running pods and then I'll see if it runs any better. Right now there is way too much air getting in and making it run rough.
 
Well that's my guess. Right now It starts right up when the choke is closed but as soon as it opens, it dies. I think the carbs could use a rebuild but I think it would be unwise to tear into that before getting something on their to filter air (be it stock box or pods).
 
Could very well be. I'm learning as I go here with this project. Right now with no filters it will not start at all with the choke even cracked open. If I close it all the way then it fires right up and runs great. As soon as I crack the choke, it dies. Regardless, I don't see much point in messing with carbs before there is at least SOME kind of intake/filter on the bike. I found the parts today. Should be here in a week. The other issue I found last night was that the frame is a 550 but the motor is a 71 500. This is not a big deal to me at all as it's just a project for me.
 
The front brake had the switch necessary to activate the stop light but I had to figure out the wiring. Got that done tonight. I then noticed a really small oil leak so I pulled the left side engine cover off and it looks like the shifter shaft seal is done. I'll see if Apex has that tomorrow along with the clutch rod seal and counter shaft sprocket seal.
 
Run a longer cable and reroute that clutch cable. That thing must be a work out to use. Holy arm pump. The more fluid and straight it is the smoother it will function. If you get a new cable hang it vertically and run a cleaner down the sleeve and move cable to get crap out.
 
New shift shaft seal and counter shaft seal are in and my NOS stock air box parts are on the way from Maine.
 
I don't have much to compare it to but I didn't think the clutch was that bad. Although it loops between the trees, it then runs straight back and under the tank and then drops straight down into the left side cover.
 
Got the left side cover back on Sunday but it wouldn't start. There ended up being an issue with the neutral switch. Cleaning and bending a contact tab seemed to do the trick. Tonight I got the neutral switch wires tucked back in, clutch cable pulled and lubed, left side cover back on, clutch cable adjusted, left rear shock pulled and polished, left side exhaust pulled and polished and then pulled a header stud out of the head reinstalling the exhaust. Looks like I might luck out though and be able to get a little longer stud and find threads a bit deeper. Stock box parts came in yesterday so that might be next.
 
Long time no see Jeeps from you, but this is also a nice Project!

Carbs:

There are 2 fuel delivery circuits, idle and power.

If it will start on choke, but not idle with it off, the problem is in the idle circuit.

If it will start on choke, and idle without it, but not run once off idle, the problem is in the power circuit.

That's true of a single carb/cylinder arrangement.

The 550-4 had 4 carbs (1 per cylinder), and they all have to be synchronized so that they deliver the appropriate amount of fuel to the cylinder or cylinders that they serve to generate the most power.

SO...
Make sure each cylinder has strong spark. The 550-4 still used points, so be sure the set those up. Replace the condenser if one is present as I have seen them short out and shunt the points.
I have seen coils fail, and that will produce unpredictable results.

Take the time to disassemble and rebuild the carbs. You will thank yourself later. When it comes time to sync the carbs, the cheap gauge setup is to buy 4 HF vacuum gauges and bolt them together with a coat hanger for hanging it on the bike so you can see it.

Parts manuals are available on-line for most Honda products. The prices aren't much cheaper than when the bikes were new ;)

http://www.cmsnl.com/honda-cb550k1-four-usa_model466/partslist/

Good Luck!!

-Ron
 
Today I looked at the points. They appeared fine but the ones for cylinder 2 and 3 were off a bit. Specs called for them both to be from .030-.040. I set them up at .035. I then checked (with a test light) the timing by rotating the crank to just above TDC for cylinders 1 and 4 and it was right on the money. Same for the other 2 cylinders. So I believe timing is ok. I still need to adjust the valves and make sure the cam chain is adjusted properly but I need to wait until I get a manual. Those are the only 2 things on the 3000 mile tune up that I have not done yet.

Thanks for the info Ron. The bike fires right up but the choke needs to be closed and I will have to nurse it along to keep it from dying. It runs like poop while riding this way (meaning super slow). But once it's warm I reach down and open up the choke all the way and it runs much better but it has a bit of a hanging idle at about 2500 when coming to a stop. It will eventually fall back to 1000 but then I have to start nursing it again. I can help things with the idle screw but that just tells me that there's something else going on. I shouldn't have to do that if things are set up right. Right? I know very little about carbs. I figured that I would have to rebuild these eventually but it is a bit intimidating. I also wondered about an air leak on the boots connecting the carbs to the motor. I did replace some of the ones on the other side of the airbox but it would seem to me that the other side is more critical.
 
Older bikes tend to be a bit "Cold Blooded", and that nasty little idle problem - par for the course. Not normal, but after 30 years, poor operation can become "Normal" ;)

Carbs aren't that bad. When you take the things apart, just note where everything goes. Do one at a time so you still have a good example to go back to. Take your time and read the instructions.

The sliders/bores tend to get gouges in them after long amounts of use - no good solution, use 600-1000 sand paper to clean them up if that is the case. Bikes used a Throttle/Jet combination. When you lift the slider, you open the throttle and open up the main jet at the same time. This also bypasses the idle jet.

The boots connecting the cylinder head and the carb are dead critical as they are your intake manifold. Cracks/Leaks will cause the engine to run lean, and will make your driving experience suck. I would replace them if possible.

The connection to the airbox is not as critical, but a good seal there will get you nicely filtered air.

-Ron
 
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I may have found a big issue just now. There is a port coming off the top of the motor that is open. That's a huge vacuum leak. Tomorrow I'll plug it and see if it changes things. I will also check the hose clamps on the intake boots and then use propane to see if there are any leaks in that area.
 
Port turned out to be nothing but a missing breather tube that vents to the atmosphere. This morning I got the valves adjusted as well as the cam chain. Bike runs better but still has idle issues and poor running. Next up will be carbs.
 
There's been a lot going on with the bike. I installed a set of Clubman bars recently.



On a ride around the neighborhood a few weeks ago, the front caliper seized up. The piston wasn't retracting. So I decided that with only one front brake caliper, it might be a good idea to go through the entire system. So the caliper is being rebuilt along with the master cylinder (finished that up tonight) and new stainless lines are on the way too.

The piston looked surprisingly good. Also got a new key cut.



Caliper cleaned up pretty nicely.



I also started polishing up the forks because the PO had just primed them.



I have bar end mirrors on the way too. Tonight I started it up and realized that it's only running on cylinders 1-3. The headers for those cylinders get hot quickly but #4 is cool to the touch even after 10 minutes of running. I still haven't done anything with the carbs but I do know there is fuel in the #4 bowl. From what little I know about carbs, this doesn't necessarily mean that fuel is getting into the cylinder. I'm getting spark on #4 plug. Tomorrow I'll pull the plug after it's run for a bit and see if the plug is wet. I'm really hoping this is not a ring issue. I probably need to check compression on all 4 cylinders.
 
Master cylinder is rebuilt. Front caliper is rebuilt. Ne braided lines are installed. System is bled and feels great.



Forks were sanded and polished.



And mirrors installed.



I recently found out that I'm only running on 3 cylinders. It looks like #4 plug is fouled out due to carbon. A new plug gets spark but I replaced those plugs about 2 weeks ago and it already crapped out and it's maybe been ridden 10 miles. I think that carb is running super fat. So next up is pulling the carbs and rebuilding them.
 
It's coming along really nicely, man. Good luck with the carb tuning. My old Ducati carb gave me the fits until I found a guide online that showed me the correct float angle. After that it ran great.

If you don't have one already, go get a media-based spark plug cleaner from Harbor Freight. It'll save you a TON of money in spark plugs when you're fouling them while tuning.

Can't wait to see it finished. The CBs sound awesome when they're fired up.

Jim
 
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