Topic: NEED HELP WITH CB750K7

[Asusfang1997]

So i have a cb750K7 1977 30091Miles on it
i spent 12 hours cleaning carbs and then rebuilding air box because my grandpa let her sit and carbs got gunked up. So today i started it and it sounded great but then i realized that cylinders 1-4 were not running while 2-3 were extremely hot. I really need help he is moving soon and i need to move it soon i'm going back up there this weekend please give advice on things to try.
if you have any questions i will respond as fast as i can to give information.
-Andrew

[Asusfang1997]

This is it running before i realized that 1-4 aren't

[scottly]

Cylinders 1-4 share an ignition coil and point set. Start there.

[Asusfang1997]

could you send a link to a reliable coil pack that'll work

[scottly]

Diagnose the issue fully before replacing parts willy-nilly. The points and how they are adjusted, and condensers are more likely to be at fault than the coil. What do the 1&4 spark plugs look like? Are they fouled from before the carbs were cleaned? If so, new plugs may be all that are needed.

[Asusfang1997]

sparkplug for number 4 looked caramel colored while spark plug 1 seemed a little darker i could try cleaning them up or getting new ones

[scottly]

If the plugs aren't sooty black, they are probably OK. Check for spark.

[Asusfang1997]

Me and my grandpa held it close to the cylinder head and there was some strong spark but it was very brief then it stopped

[CB_Dan]

To diagnose if it's the coil pack, try swapping the leads from the 2,3 coil with the 1,4 coil under the gas tank. If cylinders 1,4 are getting hot now while 2,3 remain cold, it sounds very likely that you have a bad coil pack.

[pjlogue]

What Scottly said about condensers.  A fouled plug can short out the other plug on the same coil so be sure your plugs are good (or new)  If you know your plugs are good and you replaced the condenser then try starting it in the dark and look for arcing from plug leads to frame.  If none then check the coils.

-P.

[Tracksnblades1]

Check voltage at 1-4 coil with points open.

My 76f only had 5.4volts at the coils after sitting for years.  Ran on 1&4. Would not hit on 2&3 until voltage was higher than 6.5volts. After cleaning all the connections voltage is near battery voltage but not quite.

[flybox1]

download the shop manual, and do the maintenance items listed.
Most issues are remedied by doing so...

[Asusfang1997]

thats what she used to sound like

[flybox1]

Sounds ok.  With closer attention to the valves, timing, and carb sync it can be better.
No back pressure on #1 will make that carb run lean....