Topic: '77 550 project

[coldchris]

Greetings all,
I've just received a "new to me" 1977 CB550 for a birthday gift from a friend who scored a HD Sportster. I also have a 1981 CB900F that has taught me a lot about attempting to be a garage motorcycle mechanic. I must say these SOHC Hondas are way easier to work on than the DOHC electric only start Hondas. So here is where I am at...

Issues

• Carbs idle at 2000 after the synch
• Oil leaking from between cylinder head and cylinder
• Can't seem to get good flow from the gas tank

I've removed the cylinder head and torqued the nuts down in sequence and to the specs. I'm hoping to get everything put back together before the weekend so I can spray the motor down with the pressure washer and start her up to see if it's still leaking. Once I've got that issue resolved I'll tackle the rest.

[calj737]

As for the leak, there's a few rubber "pucks" that often need to replaced as the age and become brittle. Also, after torquing the head, and before installing the valve cover, re-torque the head after an overnight sit. This allows the gasket to fully compress, and then you can reach final, accurate torque.

If its idling at a steady 2k, then you simply need to lower the idle with the screw. Possibly when cleaning/rebuilding the carbs, the slides were adjusted too high open before installation. A bench synch with an 1/8" or smaller drill bit is common to lower the slides enough to have a reasonable idle before synching.

Have an aftermarket, inline fuel filter? If so, remove it. The fuel line should run straight, downhill to the carbs. Also, the tank vent could be clogged, or the petcock obstructed.

[coldchris]

Thanks for the advice calj737,
I put everything back together before I read your reply so I wasn't able to torque the head again after it sat overnight. That is a great piece of advise that I will use the next time I have to open her up.

As for the idle, it's at 2k with the idle speed screw all they way out. I did the bench synch with a 1/8" drill bit and it still was idling high. I'm going to attempt the carb synching again then take the bike around the block and make sure the oil leak is solved first. I ran it for a few minutes just to make sure that it would start again and so far, so good, no oil leakage.

I do have aftermarket inline fuel filters so I will empty the gas tank and remove the petcock to see the condition of it. I'm hoping it has a filter inside so that I can eliminate the inline filters. Regarding the tank vent, am i correct in assuming it's the hose coming from the bottom of the tank towards the front? I have no experience with this. Could I remove the hose and not run into any problems?

I doubt that I'll ever buy another DOHC bike after my pleasant experience with this SOHC.

[coldchris]

So I removed the after market inline fuel filters after I discovered the petcock already had a filter inside the tank. The issue is I still have an oil leak issue and smoke is coming from the 1 and 2 cylinder spark plug holes. Any help is appreciated guys.

[Restoration Fan]

Is it leaking between the head & the cylinders?  If so, you should replace the head gasket after thoroughly cleaning the mating surfaces.  While you're in there, replace those rubber pucks and follow the procedure cal outlined.

[calj737]

Before tearing everything down, you can re-torque the head to see if that's indeed the problem.

Remove the valve cover, loosen all head nuts in reverse sequence, then tighten in sequence in 2 steps: 8# first, then to 16# as a final sequence. Replace the valve cover, and go for a ride. Clean the motor before you ride, and apply some baby powder in suspect areas. If oil leaks, the powder will tell you where.

Don't just torque the nuts as they sit. It won't give you a proper seating on the gasket.

[coldchris]

I've ordered the rubber pucks from 4into1 since mine were stiff and didn't want to stay on after the initial tear-down. I'll clean the mating surfaces, put on a new gasket and torque things down in two stages. I'm hoping to get this sorted out soon. Thanks for the help guys.

[coldchris]

Got the gaskets on without a hitch. Started right up and no oil leak. Then I hear a noise and the motor stops, my heart sunk down to my stomach. I forgot to tighten the first bolt that I put onto the cam sprocket. I only but it on finger tight and meant to torque it down once I installed the second bolt. Needless to say, I need to replace the cam chain and find the missing bolt, which should be in the oil pan.