Author Topic: 1978 CB550 score (Read 6042 times)

Scott S · « **on:** June 28, 2011, 12:52:08 PM »

Just picked up this '78 CB550. I've been watching for a 550 engine on which to base a 605cc build and a guy sold this one to a buddy that runs a local cycle shop. He needed money bad and let it go cheap. I got it for $500.

The good: Good title, complete, really nice shape, solid exhaust, beautiful chrome on the rims, good tank and side covers with no dents and only minor scratches on the tank. It has either Euro or Super Bike bars. The gauge faces are super nice. 17K miles. Runs and shifts really nice. No leaks or drips anywhere.

The bad: It smokes out of the #1 cylinder. The boot to the air box is split on that cylinder (didn't notice until I got it home, but it's oil smoke on #1). The seat is ugly, IMO. Front tire is bald. Rear brakes suck, but I think they're just out of adjustment. Blinkers don't blink, but it has aftermarket front signals and probably just needs a different solenoid. Kill switch doesn't work, but they key and start button do. That's about it.

Pics:

Scott S · « **Reply #1 on:** June 28, 2011, 12:53:10 PM »

Bars and speedo. Is the choke on the triple tree stock or an add on?

tango911 · « **Reply #2 on:** June 28, 2011, 12:53:31 PM »

congrats!!

Scott S · « **Reply #3 on:** June 28, 2011, 12:54:54 PM »

Exhaust is really, really solid. Minor surface rust on the head pipes and a couple of small dings on the LH mufflers. Unless those are supposed to be there....never owned a '78 CB550K before.

Scott S · « **Reply #4 on:** June 28, 2011, 12:55:29 PM »

Rims are very nice. Rear tire appears to be new.

Scott S · « **Reply #5 on:** June 28, 2011, 12:59:02 PM »

Carbs are pretty clean. It likes to idle a little high....maybe because of the boot? Need a cleaning? If there's a valve or ring problem on #1, would that cause it to need a high idle? I also noticed a small flat spot or hesitation at about 5,000 rpm, but otherwise runs smooth, quiet and fairly powerful.
It still has the stock airbox with snorkel. I've seen this mentioned in a few threads, but can't remember if it's a good or bad thing. Comments? (BTW, I'm a stock airbox guy when it comes to these SOHC's. No pods for me, so whatever works best for this bike/carbs).

Scott S · « **Reply #6 on:** June 28, 2011, 01:02:43 PM »

The headlight is one of those chopper/euro style with the high beam bezel. Doesn't bother me one bit. If I keep the bike, and not just the engine, I'll change the turn signals, though. Maybe the P.O. did something to the wiring when adding these lights and that's why the kill switch isn't working? Haven't investigated any of this stuff yet.
There are also some stickers from two different Honda dealers. Here's one. I can't remember off the top of my head what the other one said.

dave500 · « **Reply #7 on:** June 28, 2011, 01:51:35 PM »

excellent score man!!that split intake boot looks like a large hole,hopefully it hasnt ingested too much debris and worn number one cylinder causing your smoke?or gone really lean on that cylinder aswell causing it to overheat and start to burn a valve,how does that plug look compared to the rest?

Scott S · « **Reply #8 on:** June 28, 2011, 02:02:49 PM »

Good questions, Dave. I haven't pulled a plug yet. The rest of the bike was just too good to pass up and, like I said, the original intent was to use the engine as a basis for a big-bore engine for my CB500. But now that I have it home....man, this thing is pretty nice. A seat change, a little top end work, new front tire and away I go!

Scott S · « **Reply #9 on:** June 28, 2011, 02:19:59 PM »

Pulled #1 and #4.
#1 doesn't look that bad.....a little lean, but not oil fouled.
#4 looks rich, but reasonable, especially after idling and low speed maneuvering around the garage when I got it home.

I peeked into the spark plug hole on #1 and can see what appears to be a valve relief on the top of the piston, intake side. Is that supposed to be there or has a valve touched the piston in the past, maybe?

Also, it looks like the #1 spark plug is newer than the rest, so someone knew about the problem, whatever it turns out to be.
I have to idle it up top get it to crank, but it'll fire right up and idle on its own.....albeit a little high. No funny valve or cam chain noises, although I'll probably adjust both and see if it helps.
I think I may have a spare airbox boot somewhere, if they're the same as the CB500.

dave500 · « **Reply #10 on:** June 28, 2011, 02:38:54 PM »

ok cool,yeah id try and run it for a while with out idling,can you ride it up and down your street,is it licensed?someone savvy might replace a plug with one hotter on a troublesome cylinder,are they the same heat range?it might just need a good ride to clean it out if it hasnt been run for a while,you intend to rebuild this anyway so long as the engine isnt damged itll be ok,,those valve reliefs are normal.

the left standard one shows your reliefs,the right one is an xl125 piston,i used these in a 500.

Scott S · « **Reply #11 on:** June 28, 2011, 02:52:20 PM »

I can ride it around my neighborhood. I live out in the country and no one would care. Good to hear about the valve relief.
The more I think about it, the more I suspect a broken ring. It just runs too good and too quiet.

Oh, forgot to mention: Hit it with my IR temp gun after idling and all four exhaust pipes are dead on, #1 and #4 cylinder measure the same, as do the #1 and #4 carbs.
I also adjusted the rear brake and fixed 90% of it. Looks like I could start from scratch with the lever/pivot/arm and get the rear brakes to work just fine. Same with the front. I kinda get the idea that someone just didn't know that much about owning a vintage bike.

Scott S · « **Reply #12 on:** July 01, 2011, 06:53:21 PM »

Ahhh, MUCH better! Picked up this seat from a guy in Charlotte today. Makes the bike look a hundred times better. Anyone interested in a really nice Corbin Gentry seat and/or backrest/luggage rack?

Scott S · « **Reply #13 on:** July 01, 2011, 06:54:22 PM »

What can you tell me about this choke set-up?

EDIT: After checking Motogrid, I guess it's stock. Hmmm, never seen that before.

Stev-o · « **Reply #14 on:** July 01, 2011, 07:06:12 PM »

Wow, great buy! Thank you for changing that seat, chunk the old one in the trash (bet you won't get any takers).
You need to check compression. And what is a "little high" on the idle? My 550 likes 1800, higher than what most other guys will tell you.

Order a tire from Motorcyclesuperstore.com

Scott S · « **Reply #15 on:** July 01, 2011, 07:15:00 PM »

I haven't really messed with tuning it too much. I have other projects that take precedent, but the seat was too good of a deal to pass up.

I KNOW the #1 carb to air box boot is busted and it's definitely smoking on that cylinder. I haven't done a compression test yet, but I suspect a broken ring. No matter what I do with the choke, I have to turn the idle screw in to get it to crank. It will fire right up then, like immediately, but idle at over 2,000. I may be able to get it down to ~1800 (don't really remember). It's not normal for it to idle that high is it?

Where can I find a carb to air box boot? Thought I had a set from a '75 CB550 that would work, but they're different. The '75 (and the ones for my CB500) are all shorter than what's on the '77. I can't seem to find a cross reference for other models, either.

dave500 · « **Reply #16 on:** July 02, 2011, 02:06:47 AM »

i see your on it but that air leak must be fixed before any decent tuning gets done,at least try and wrap some tape over it if you need to ride it up and down your street(who could resist?),when you find a new one you should be able to wrangle it into place without pulling the carbs,unless you want to?can i come and live in america for six months and buy all the cheap bikes around?nothing like that ever goes cheap down here,,we see it all the time,,maybe the states got flooded with these things,,our population in the 70s would have been way lower than yours aswell as the average age etc or some stuff concerning the motorcycle market.

bender01 · « **Reply #17 on:** July 02, 2011, 04:49:28 AM »

Thats a good buy around here. The pipe dimple looks like the centerstand resting spot.

Deltarider · « **Reply #18 on:** July 02, 2011, 05:12:34 AM »

K4 model. Congrats. Good you removed that horrible seat. Excellent bars. BTW, you guys leave me stunned everytime: 17k miles. What kind of a market is it overthere? Toycollectors? People buying motorcycles and then find out they're too scared to ride it? In all of Europe you will never find such a bike with so little distance travelled.

cb550inct · « **Reply #19 on:** July 02, 2011, 12:17:02 PM »

Great bike...I have the exact same bike year model. (idel issues). But i have a question to the whole forum Why is my tach and speedo different. Mine have the ND logo on the bottom not nippon, Did they use both on cb550's or di somone switch mine

Scott S · « **Reply #20 on:** July 02, 2011, 01:24:42 PM »

You're the second person to tell me that his 550K likes a high idle, too. The other guy said his is "normal" at 1800 rpm. Maybe something to do with EPA settings?

TwoTired · « **Reply #21 on:** July 02, 2011, 01:32:27 PM »

Quote from: Scott S on July 02, 2011, 01:24:42 PM

You're the second person to tell me that his 550K likes a high idle, too. The other guy said his is "normal" at 1800 rpm. Maybe something to do with EPA settings?

No it doesn't, ALL the cb550s will idle at 1000-1100, if the mechanic knows how to tune the bike and set it up properly.

This is how stupid rumors get turned into mythology and folklore. It's usually done by old wives.

Steve_K · « **Reply #22 on:** July 02, 2011, 01:48:57 PM »

Nice Bike! That choke pull is just like the one on my 77 CB550.
Steve

Roach · « **Reply #23 on:** July 02, 2011, 02:08:09 PM »

if you are looking at the blinkers make sure the front ones are duel filament or they wont blink!!!

Scott S · « **Reply #24 on:** July 02, 2011, 02:49:43 PM »

Yeah, both blinkers will light up but not blink. It's probably because the P.O. added the aftermarket front blinkers but didn't change the flasher relay. I'm still deciding whether to go back stock or all four aftermarket. Either way, I'll get them working when I decide.

TwoTired, I didn't THINK that 1800rpm sounded normal, but I've never had a 550K before. I'm sure that the busted air boot, #1 cylinder issue (I suspect a broken ring), and general need of a tune-up has something to do with it. When the time comes, I'll roll up my sleeves and dig in. If I could get that barn find CB500 purring, I know I can do this one, too! It's a much nicer base on which to start.

News:

Author Topic: 1978 CB550 score (Read 6042 times)