Topic: 76 CB550K - What to do next?

[ajinreno]

Still trying to fine tune my 76 550K. It runs, doesn't leak anymore, but still occasionally acts like its starving for gas. It seems to do it more when i ride for extended periods at high rpms, like on a freeway. Even when it' not doing that, it has some flat spots in the throttle. My plugs are covered in black carbon, put a hotter plug in and it is still covered in carbon. My air mixture is at 1.5 turns. Could this all be the result of weak spark? Should I just buy a Dyna S electronic conversion? The bike is at a higher elevation now, about 5,500 feet. Could it need rejetting? Thanks for any advice on what I should try next...

[mattcb350f]

The bike sounds as if it's running rich, but it could also be a symptom on not having enough back pressure in the exhaust system 

 Matt.

[Klark Kent]

I wouldn't run out and get an electronic ignition until I fixed the problem, but if you do Hondaman makes an electronic ignition that improves the low end and the very high end and is less taxing on the system in general than the DynaS.  Before any of that though it sounds like you need to sort out your jetting.  With a set up like yours (sweet by the way) trial and error seems in order and plug chops and this chart are all you need right?

good luck

[Jay B]

You didn't say how it is set up now, but if it's stock or set up for a much lower altitude, it's probably running quite rich. 5500ft is pretty high. I know this is sort of apples to oranges, but my brother and I are really into snowmobiles. We live at about 1050ft above sea level. We frequently go the Black Hills, and ride in the 4-6000 ft range. Requires significant rejetting. 2 strokes are very sesitive to this though, there's generally a jet chart based on altitude and temp under the hood.