1. i was wondering if anyone had any experience with bolting on CB750 carbs on to a 1978 CB550.
-does it work?
-how did it work out?
-are the proformace increases worth it?
-any down sides to it?
Rob Lloyd did this to his 550, and had mixed results. It didn't like idling, and wasn't easy to start, but there WAS a power gain to be had. The smallest jet you can get for the 750 carbs is a 35, and apparently even that is still too much; however, you can use a propane torch to solder the jet shut and then redrill it to an even smaller size with a wire size drill bit. Takes a lot of trial-and-error work to find the right size, but I think it could be done. You'll likely introduce an off-idle stumble unless you play with needle heights and shapes, slide cutaway shapes, and other technical stuff.
Personally, I feel that if you don't have any engine work done, you won't want the 750 carbs- they simply flow too much for an unmodified engine.
3. i was thinking of putting a Dyna S ignition on my bike to replace the points.
i was told that i should replace the coils too while I'm there.
-what do you think about the system?
-is it worth the change?
-are there any performance increases?
The benefit to electronic ignition is not performance, it's reliability. You often hear the phrase, "set it and forget it" used with EI, for a reason- you set it according to the book, set the timing, and you never touch it again.
You CAN change the coils, but unless the EI requires a different coil value (many EI's require 3 ohm coils, points use 5 ohm coils), you don't really need to. Most aftermarket coils do have a higher output voltage than stock coils, so you can increase the plug gap which gives you a larger spark for more complete burn. Still not really a 'performance increase', but certainly a reliablility increase. Whether it's worth it or not is up to you.
