1974 Honda CB550K Help

Picked up a CB550K about 6 months ago and I'm finally finding some time to mess around with it. I am able to get it running, however, the idle is erratic and it is will eventually die if I let off the throttle. After I let it die I cannot get it to start again. I have to let it sit for about 15 minutes. It also has a new battery and I'm not able to start it unless it's hooked up to a charger. It did the same thing before I replaced the battery as well. I have recently cleaned the carbs and replaced the petcock and fuel lines. Any advice on where to start would be greatly appreciated!


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Bump


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Sounds like a fuel/air problem.
Clean the carbs again. Clean them once more. Clean them a fourth time. Be sure to really clean the jets and all the little holes about the carbs.

After that, check your idler screw. It's a big thumb screw on the right hand side of the carbs. Make sure it's open enough to get it idling after she starts up, but not open enough to lean out the fuel air mix too much and have her putter out.

Check your spark plugs. Take pics and post them here.

Also, provide us with some numbers. What's your bike idling at? Have you got compression numbers on each of the cylinders? Report back. I'll help as much as I can.

Could be your timing, improperly set valves. First check your compression on all cylinders.It sounds like you need to go through the standard tune up procedure next (cam chain tension, valve tappet clearances, ignition timing). Then go ahead and make sure your carbs are spotless as stated above. Then report back.


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adventurco said:

Could be your timing, improperly set valves. First check your compression on all cylinders.It sounds like you need to go through the standard tune up procedure first (cam chain tension, valve tappet clearances, ignition timing). Then go ahead and make sure your carbs are spotless as stated above. Then report back.


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Click to expand...

*high fives emphatically* teamwork!

check boots

You guys are awesome. I'll have some time to check it out this weekend and I'll report back. I actually was able to kickstart it today without a charger. It revved up to about 4k rpms and died.

In order of easy to hard:

First check the idler screw. Then get it running and spray wd40 around the boots the see if that affects the rpms. Then check compression. Then go through maintenance as suggested by adventurco. Then clean the carbs.

Check battery voltage first.


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Well I decided to clean the carbs and of course ran into more issues. The previous owner used a ton of different screws and stripped out the fuel bowl holes on 3/4 of the carbs. Looks like I need to find another set up carbs and rebuild them. Anyone know what CB550 carb years I could use?


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Can you tap the bolt holes, even if you have to go up slightly in size? Get some nice allen head screws for replacement? Maybe use small locking nuts with longer screws? Either way, much cheaper.

One other thing I ran into on my 550...get all of the basics where they should be...clean carbs, throttle cable tension, idle screw (it should be set somewhere in the middle...cranked either in or out to extreme indicates that something is amiss), throttle stop screw, tappet clearances, timing, choke circuit, good battery and connections, boots intact, airbox or pods correct...everything.

Here is what I found...with all of this stuff in spec, it still may not idle. Do whatever you must to then get the carbs sync'd. A HUGE requirement. and may take a couple attempts.