Its not the carbs ... its electrical

[Myumi-2]

Ive been restoring a cb750 K2.

It ran well, started easily, I'd gotten it up to 100 miles/hr and have riden her daily for the past year.

There were a few ongoing performance issues that Id not been able to resolve.  In particular, when maintaining a constant speed with RPM at about 4500 it tendered to stutter a little.  Not a consistent stutter but noticable.  Also when accelerating from a standing start there was a pause in power at about 1/8 throttle.  If you were turning tightly at low speed it could cause a nuisance.

I'd assumed a Carb issue.  I re-jetted, Synced, re-cleaned, asjusted the slide and air screws etc, etc.  Nothing fixed the problem.  I just choose to ride the bike a bit harder and accept these imperfections along with the poor fuel economy.

For the sake of it and as a last resort, I replaced the points plate with an electronic ignition and the difference is remarkable.  The points were in good shape and I did not expect to get much out of an electronic ignition, but I did.

The pause and mid range stutter have gone.  There is more power and I could be mistaken, but it sounds better too.  

Ive only been for a short test ride, I still need to put the timing light on, but it was one of those moments where you've spent lots of money and wonder if you will notive the difference, but it was money well spent.

Now that the electrics are working better, I suspect I can re-adjust the carbs and get even more out of this old girl.  I will replace the coils as well.  Whilst I think they are working well, I also thought the points were working too.

[Tech78]

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[Re-run]

What ignition did you get? Make sure if you get new coils that they match the ohm requirements of the ignition. Also, as a precaution, make sure all your charging system connections are in good shape.
If you end up with lower ohm coils (5 are stock) there is more of a strain on the charging system.

[woodsrider250-2]

Just curious, but why would lower ohm coils cause a strain on the charging system?  What they can do is cause too much heat in your new ign box  (IE install 1.6ohm MSD-only coils onto a plain old Dyna), and cause it to burn up.

[Myumi-2]

It is the Dyna ingnition.

What Coils would you recommend?

[Tech78]

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[Re-run]

Which dyna? I am guessing the S.

The Dyna S can use either 5 ohm or lower 3 ohm coils.
The 3 ohm provides a hotter spark but creates more of a draw on the charging system. The 750 charging system is up to the task when in good shape. However, if the system is not in good shape, it may either fail of not charge the battery enough and leave it flat at some less than spectacular moment.

That should answer everyones question on that.

[Tech78]

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[Re-run]

It should be fine as long as everything is in good order.