'80 750c ignition issues

[hellsford]

i've been a lurker of this amazingly awesome site for about a month now. recently purchaced a 1980 cb750c and am currently in the middle of a carb rebuild (almost had everything together until i realized my floats were compromised). My bike has always had issues starting, esp. when cold outside. I recently read that the NGK BR8EIX plugs can fix the issue with lower gap resistance, but i also read that some 90's GM coils are a much better replacement for the approx 30 y/o honda coils. Could someone please give me some info on this?

thanks in advance for all the help

[hellsford]

Also, looking for as much info on the bike as i can get, Vin#RC012201749 Engine#RC01E2115565. I work for advance auto, so i have access to decoding 17 didget vins on most cars and trucks, but i don't know where to start on these old bikes.

[motogrady]

from what I hear, both items you describe help.

[TOOLS1]

I would start with the Iridium plugs. Just because the coils are old does not mean they are bad. However a few years ago a member going by the handle "Pinhead" did a writeup on installing the GM coils. You can find it by doing a search for "Pinhead". However another cause for cold starting problems is dirty pilot jets.
TOOLS

[shinyribs]

TOOLS1 wrote

 However another cause for cold starting problems is dirty pilot jets.
TOOLS

And faulty accel pump circuit and a non-working choke. These CV carbs have funky choke linkage. Make sure your choke is actually closing when you pull the cable. I ran in to this recently.

[hellsford]

Yeah the choke does seem to be a littly funky on this thing, the cable is extremely tight, ill probably oil it up a bit. Thank you all for the help. As soon as I get the floats for the carbs, I should have it back up and running. Already got the iridium plugs.

[LukeM]

According to the frame and engine IDs, you have a 1980 US model CB750c, as you mentioned above. The Haynes manual for these bikes says that the 1980 model was essentially a K model with some cosmetic upgrades.  In 1981 and beyond, it branched out a bit more with some modifications (front forks, axle first front wheel, twin front disk brakes, etc).

Hope this helps.
Luke M

[hellsford]

Thanks Luke, by any chance is there a way to tell if that engine is original to the frame?