Topic: 1974 CB550k Boss Maroon

[brett_bike]

Just removed carbs and having my son 3D print me a float measuring tool. I’ll check all of the floats I have the rack off the bike.

I know that was an issue but was it THE issue?


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[denward17]

Well, if rich enough on that #1 cylinder, I guess it would kill the spark, so in effect running on 3 cylinders.

Would it run if you kept milking the throttle, or would it die either way?

If so, I would say this might not be the whole problem but certainly contributed.

[brett_bike]

Well, if rich enough on that #1 cylinder, I guess it would kill the spark, so in effect running on 3 cylinders.

Would it run if you kept milking the throttle, or would it die either way?

If so, I would say this might not be the whole problem but certainly contributed.

Today I had some time in the garage to re-set the float in carb #1 and verify the others were good.

I started to put the carbs back on the bike and hooked up the throttle cables.

In the morning I will reinstall the airbox and air plenums and see how she rides.


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[brett_bike]

I forgot to mention that I also lowered the needle one clip during this struggle.

Finished putting everything back together this morning and took it out for a spin. 20 minutes and it didn’t die on me. It stumbles a bit cruising around 4000 rpm’s. Not sure if that’s a jetting issue, maybe a timing advance issue(?). Is that a thing?

Unfortunately I changed three things during this debacle so I can’t confirm which one was the true fix. Along with lowering the needle one clip, I replaced a condenser and reset the floats.

Anyway, I need to get back in and redo the valve lash because I’ve now ridden it more that 3 minutes I can hear some excessive ticking from 1 or 2. I’ll obviously confirm all is set correctly.

Now onto more new parts. Tires, exhaust, Hondaman transistorized ignition module, tapered headset bearings, chain, etc.

Will post as I go down that road.


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[brett_bike]

Question about the valve noise.

How much ticking is too much?  It seems to more pronounced on the left side.


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[denward17]

Question about the valve noise.

How much ticking is too much?  It seems to more pronounced on the left side.


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Does it sound like this?

https://photos.google.com/share/AF1QipOUyM6MpkfP7248ZiIL8KMXyWb37uK8U0pSa8KsLpw6qTq8_8R-_CxCzmq1lNrPHA?key=RW5XNVlRdi1KQXJJVnNvME9JUjlaaDJsZjBHZk1B

That's my '76 550 that had a bad valve cover rocker shaft, and I recently installed a rocker cover from a '77/'78 model that has pinned shafts.

[brett_bike]

I don’t think so.  Hopefully not.

I had to do that mod to my old 73 500.

I can hear a different sound coming from the back side of the cylinder from the front of the cylinder so I’m hoping it’s just a rocker adjustment.

If I can figure out how to post a vid I’ll update.


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[RAFster122s]

Pulling end caps on rocker cover you can see ends of shafts and if worn significantly it will be clearly visible.

[calj737]

With only 8700 miles on it, I doubt the rocker shafts are badly worn.

Did you install fresh plugs or clean up your old ones after the carb adjustments?

[brett_bike]

With only 8700 miles on it, I doubt the rocker shafts are badly worn.

Did you install fresh plugs or clean up your old ones after the carb adjustments?

I cleaned up the old plugs and took her for about a 20 min ride. I had to run to work but I’ll check them when I got home.


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[Stev-o]

Question about the valve noise.

How much ticking is too much?  It seems to more pronounced on the left side.

My 550F sounds like a sewing machine!  Have you sync'd the carbs yet, that may quiet it a bit?

[brett_bike]

I removed the carbs to redo the bench sync. I’ve also redone the valve adjustment.

I’ve been out of town in a work trip but getting home tonight, so tomorrow the carbs go back on and final (hopefully) vacuum sync.

Will report back after test ride.


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[brett_bike]

Finally had some time to take the Boss for a ride this morning.

We were out for about 20 minutes and here’s what’s up…

Idle screw is turned in more than I’d like so it won’t die on startup. After warm up it idles about 2500 RPM’s so I have to turn idle down to 1000-1200 at the next stop sign. Then it’s fine for the rest of the ride.

Mostly strong pulling until between 5-4k RPM’s. Then it’s stumbles/blubbers a bit till I give it more throttle then she screams up to 9k.


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[denward17]

What do your plugs look like now after the ride?

[brett_bike]

What do your plugs look like now after the ride?

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[brett_bike]

Left to right…1234


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[denward17]

So you leaned it out by lowering the needle one clip, right?  What position is the needle now and did it run like this before you adjusted the needle?

[brett_bike]

I lowered the clip, raising the needle.

It stalled before the latest “fix”. Now it at least rides without dying when I come to a complete stop.


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[denward17]

What is your air/fuel mixture screws set to?

[brett_bike]

What is your air/fuel mixture screws set to?

1 1/2 turns out.


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[denward17]

You could try different settings on the air/fuel mixture to see if it makes a difference.  Try 1 turn out, then try 2 turns out.

[grcamna2]

Nice find, don't see original Boss Maroon that often.  +1...change condensers with known OEM

Real nice looking bike;a previous owner kept it inside 

[brett_bike]

Nice find, don't see original Boss Maroon that often.  +1...change condensers with known OEM

Real nice looking bike;a previous owner kept it inside 

Thanks grcamna2, but it looks better in pics that in person. However, this isn’t going to be a show bike. I intend to put some serious miles on this little thing.


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[brett_bike]

Update…

Clip in middle setting. New plugs.

After a 30 minute ride here is what the plug deposits look like. 1-4 left to right. Oddly enough1 & 3 look ok, maybe a little rich.  But 2 & 4 look really lean.

What could I be missing?



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[calj737]

I have never placed much value in reading plugs after a “ride” because their condition does not tell you position of throttle that the state is occurring. It is best practice to start clean, fresh plugs, and do a plug reading at idle. Then again at WOT and chop the motor. Pull the plugs roadside and snap pictures of them. Then return to the garage to make any adjustments needed.

From looking at the picture, I’d say your fuel level is wrong on the carbs if all other settings are equal. If the bike is running strong, that somewhat rules out ignition issues, but not entirely.