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Author Topic: 1975 CB550 help needed  (Read 871 times)

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Offline MJBolduc

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1975 CB550 help needed
« on: February 18, 2020, 08:28:54 AM »
Last night I hurt my baby. White smoke/exhaust coming primarily out of tube behind motor from top of motor. Exhaust valve? Rings? Any help is greatly appreciated. Plan to pull motor this weekend.
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Offline flatlander

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Re: 1975 CB550 help needed
« Reply #1 on: February 18, 2020, 09:31:36 AM »
is the engine fully warmed up when you see this, or still somewhat cold? did it stand still for quite some time?
that tube evacuates blowby gasses. if you're lucky you just have some condensation in a cold engine that will burn off when warmed up.
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Offline bryanj

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Re: 1975 CB550 help needed
« Reply #2 on: February 18, 2020, 09:38:41 AM »
These are a very robust engine, valves rarely go guides dont wear much. Me i would change oil and filter first set valves and timing and see how it runs
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Offline MJBolduc

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Re: 1975 CB550 help needed
« Reply #3 on: February 18, 2020, 09:45:00 AM »
Unfortunately I was riding it when this happened. Sustained 6-7k rpm and felt a change in the motor, saw smoke stopped and called Hagerty to come get my sorry butt.
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Offline dave500

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Re: 1975 CB550 help needed
« Reply #4 on: February 18, 2020, 11:36:06 AM »
6-7 or 8 grand wont hurt these engines,if you were running lean a hole in a piston?what intake set up do you have?
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Offline MJBolduc

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Re: 1975 CB550 help needed
« Reply #5 on: February 18, 2020, 11:55:57 AM »
Pretty standard stuff.
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Offline Tracksnblades1

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Re: 1975 CB550 help needed
« Reply #6 on: February 18, 2020, 01:03:22 PM »
Quote from: MJBolduc on February 18, 2020, 09:45:00 AM
Unfortunately I was riding it when this happened. Sustained 6-7k rpm and felt a change in the motor, saw smoke stopped and called Hagerty to come get my sorry butt.

What kind of change did you feel?

Things wanting out noises?  Engine feeling like it's going to sieze?
Engine dropping power? Missing?

Compression test will identify faulty cylinder. Piston and piston rings sealing problems can show up as blow by.
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Offline MJBolduc

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Re: 1975 CB550 help needed
« Reply #7 on: February 18, 2020, 01:15:20 PM »
Drop in power, throttle less responsive.
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Offline Tracksnblades1

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Re: 1975 CB550 help needed
« Reply #8 on: February 18, 2020, 01:20:36 PM »
All 4 exhaust pipes still hot when running for a short time?
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Offline Bankerdanny

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Re: 1975 CB550 help needed
« Reply #9 on: February 18, 2020, 01:37:02 PM »
Quote from: MJBolduc on February 18, 2020, 01:15:20 PM
Drop in power, throttle less responsive.

When this happened to me on a 2 week trip in the middle of the desert there were 2 different causes and solutions.

The first time was failure of the vintage electronic ignition when the engine got hot causing me to lose 2 cylinders. Switching back to points fixed that.

The 2nd time a lock nut had backed off of the #1 intake adjuster, which then backed out so that the valve wasn't opening, no open = no fuel = no run on that cylinder. The acjtual adjusted screw bent and another member here, TwoTired, drove a couple hours with a spare part and helped me install it so I could keep going the 1300 miles left in my trip.

Drop in power generally means one or more cylinders is not firing. Others have laid out a path for you to follow to diagnose the problem. Be systematic and you will figure it out.
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Offline dave500

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Re: 1975 CB550 help needed
« Reply #10 on: February 18, 2020, 10:38:21 PM »
that air filter set up looks like you may have run lean?wonder what jets are in it?
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Offline Deltarider

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Re: 1975 CB550 help needed
« Reply #11 on: February 18, 2020, 10:51:02 PM »
Any inline fuel filters that may have compromised fuel flow resulting in running too lean?
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Offline Deltarider

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Re: 1975 CB550 help needed
« Reply #12 on: March 03, 2020, 07:39:20 AM »
Any success yet?
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Offline RickThomas

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Re: 1975 CB550 help needed
« Reply #13 on: March 04, 2020, 05:44:51 AM »
If you remove the dipstick, was there smoke coming out of the hole? Although it's February now, I had a similar issue when my engine was running leaning. I was on the interstate doing about 80 MPH with 10w-40 oil in the summer at 90 degrees. I started to get some smoke out the crankcase breather and also the oil dipstick. The reason it caused me to stumble is that the crankcase breather is sent to the bottom of the factory airbox so it choked itself out. Switched to 10w-50 and all was well after that.
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Offline Deltarider

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Re: 1975 CB550 help needed
« Reply #14 on: March 28, 2020, 04:36:08 AM »
Bolduc, you have received a PM with:
To make our forum a success, it would be great if people would report back if advice offered has been useful. At least 7 members that tried to help you and many others are still unknowing if you had any success.
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Offline robvangulik

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Re: 1975 CB550 help needed
« Reply #15 on: March 28, 2020, 07:23:54 AM »
Last active Feb 18....
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