Top end misfire, 550

[Hardy]

Hi, I have a 79 gs 550B (Australia/NZ model #) the bike was fairly chopped up when I brought her (a fool and his money) anyway I've fallen for the bike so here I am. The problem is at the top end of most gears the bike misfires. The previous owner put a cheap set of pods on and the first thing I did was re-kit (with a stock kit) the carbs this made no difference. Do I need to port the carbs when running pods? Next up the four into one had the baffle removed so I have replaced it with the origanal but no packing? no difference. So next I'm replacing the points and I geuss if that doesn't work its off with her head! The bike runs quite strong but could do with a set of rings, but if I could get away without stripping the engine I think I'd get a few more km's out of her. any help would be greatly appreciated. Thanks Hardy

[tkent02]

Hi, I have a 79 gs 550B (Australia/NZ model #) the bike was fairly chopped up when I brought her (a fool and his money) anyway I've fallen for the bike so here I am. The problem is at the top end of most gears the bike misfires. The previous owner put a cheap set of pods on and the first thing I did was re-kit (with a stock kit) the carbs this made no difference. Do I need to port the carbs when running pods? Next up the four into one had the baffle removed so I have replaced it with the origanal but no packing? no difference. So next I'm replacing the points and I geuss if that doesn't work its off with her head! The bike runs quite strong but could do with a set of rings, but if I could get away without stripping the engine I think I'd get a few more km's out of her. any help would be greatly appreciated. Thanks Hardy

Troubleshoot, repair, adjust everything, or keep guessing until you are out of money.
Misfiring is probably ignition related, troubleshoot this first.

[chef1366]

You need to rejet for pods. Put the stock airbox back on with the stock jets. You can burn up the motor with a lean condition.
tkent02 is correct that a motor that breaks up is normally ignition related. Check the mechanical advance and make sure it isn't frozen up or stiff.

[DMPLATT]

With PODS and the Baffle removed, if the carbs weren't jetted, definitely a lean situation.
How do the plugs look? That's the easiest way to see if it's running lean.

[Dave8338]

Lean

With PODS and the Baffle removed, if the carbs weren't jetted, definitely a lean situation.
How do the plugs look? That's the easiest way to see if it's running lean.

+2 on a lean break-up on the pilot-main transfer. Start as mentioned, putting things back the way they should be and go from there. That or play the rejet game and if you question your carb skills, I'de suggest the prior option.