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Author Topic: 1972 Honda CB750 K2 sounds like a Harley  (Read 404 times)

Offline Jrperida

  • Posts: 15
1972 Honda CB750 K2 sounds like a Harley
« on: Jul 31, 2017, 01:32:19 »
So I recently got my bike up and running, installed a 4 in 1 MAC exhaust system but noticed the overall sound of the bike is more like a Harley rather than a typical Honda CB750. I'm not really familiar to what affects the overall sound of the bike. Could it just be the exhaust system I installed? if so, would there be a way to just change out the muffler? OR do I need to re-jet the carbs?
« Last Edit: Jul 31, 2017, 02:19:50 by Jrperida »

Offline datadavid

  • Posts: 1097
Re: 1972 Honda CB750 K2 sounds like a Harley
« Reply #1 on: Jul 31, 2017, 02:26:25 »
Its only running on 2 cylinders

Offline hillsy

  • Posts: 4087
Re: 1972 Honda CB750 K2 sounds like a Harley
« Reply #2 on: Jul 31, 2017, 02:45:22 »
Its only running on 2 cylinders


Dead coil.

Offline datadavid

  • Posts: 1097
Re: 1972 Honda CB750 K2 sounds like a Harley
« Reply #3 on: Jul 31, 2017, 03:49:22 »
Yah, or weak/marginal spark and rich mixture from not adjusting idle mix and needle height. Check coils first then jetting. You definitely need to rejet, but first things first, swap over coils and see if problem moves.

Offline Jrperida

  • Posts: 15
Re: 1972 Honda CB750 K2 sounds like a Harley
« Reply #4 on: Jul 31, 2017, 22:01:54 »
The coil's are brand new, got them from vintage CB750. I'll probably check out the spark plugs to see if the mixture is too lean or rich then adjust the jets as necessary. Could I just adjust the jets or do I also need to adjust the needle ?

Offline coyote13

  • Posts: 1136
Re: 1972 Honda CB750 K2 sounds like a Harley
« Reply #5 on: Aug 01, 2017, 11:30:09 »
Do you have a muffler on that 4-1?  I ran open headers for shits and gigs one day and it sounded like NASCAR
Half the fun's in the get there...

Offline irk miller

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Re: 1972 Honda CB750 K2 sounds like a Harley
« Reply #6 on: Aug 01, 2017, 15:15:59 »
Make sure you have your coils set up correctly, too.  1/4 on the left coil (blue) and 2/3 on the right coil (yellow). 

Offline hillsy

  • Posts: 4087
Re: 1972 Honda CB750 K2 sounds like a Harley
« Reply #7 on: Aug 02, 2017, 00:31:56 »
You might be best off posting a video of what your bike sounds like - my dead coil comment was just throwing shit at the fan because your idea of sounding like a HD might not match anyone else's idea.

Offline spotty

  • Posts: 852
  • Vmax...why,yes i think i will
    • spottys world of vmax (and great danes)
Re: 1972 Honda CB750 K2 sounds like a Harley
« Reply #8 on: Aug 02, 2017, 00:36:01 »
Do you have a muffler on that 4-1?  I ran open headers for shits and gigs one day and it sounded like NASCAR

you want to try that with a Vmax, sounds like a top fueler ripping the universe a new one
short fast loud, three things punk rock and vmaxs have in common

south of the border, down melbourne way

Offline Jrperida

  • Posts: 15
Re: 1972 Honda CB750 K2 sounds like a Harley
« Reply #9 on: Aug 12, 2017, 18:13:54 »
Re adjusted the ignition timing & fixed the wiring for the coils did the trick. Although I'm noticing white smoke from my exhaust pipe and the front portion of the engine close to the exhaust connection. This isn't normal is it?