Topic: my cb550f wont run right

[trent194]

Hello I am a new member, I have had my bike for about a year and a half a 1975 cb550f.  Ever scence I got it I have had a problem, the bike will run awsome for like five to ten miles then I will lose power in 1 and 4, I thought it was just too lean bumped up to a 120 main that didn't fix it, after it sits for a little while it will fire back up and start the whole process back over, I thought maybe it was a coil and my uncle said that too but he has never had a bike as far as I know so I am just looking for some advice before I drop any more money into this bike.
thank you
trent

[1timduke]

I think it's an ignition problem, this guy seems to have a similar problem...http://forums.sohc4.net/index.php?topic=56561.0

First, make sure your timing, points, valve adjustment, plugs, etc... are all correct and in tune, then if it's still off you can delve into the condensers and coils.

-Tim

[honda750k]

sounds like a coil or condenser to me.  my friend's dad had an RD400 that did the same thing, would run for a few miles, then die.   was a spark issue. 

new coils, some fresh condensers, and check your timing is right.

[OldSchool_IsCool]

+1 on the 3000 mile tune-up in your service manual.  If that doesn't fix it, swap you condensers and see if the problem moves to 2.3.  Better yet, condensers are cheap.  Get new ones as well as new points.  Clean new points with a white business card soaked in brake cleaner.  Maybe new plugs too. 

Another place to check is the plug caps.  Pull them off the wires and if you see any green corrosion in there, trim off about a quarter inch to get to clean copper and shine up the spike inside the cap.  May as well check the cap resistance too (should be 5K ohms, or is it 10k, I'm not sure on an F).

Start with the free stuff, then the cheap stuff.