Author Topic: 74 CB750 Carbs 2 & 3 Sooty Rich After Cleaning  (Read 1144 times)

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Offline Wingnut74

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74 CB750 Carbs 2 & 3 Sooty Rich After Cleaning
« on: July 22, 2016, 02:38:50 PM »
 I rebuilt the carbs completely after I rebuilt the engine and everything was working fine in terms of richness the plugs were a perfect light brown color on all four carbs. T then I developed a very slight stammering problem than I originally thought was fixed but I blamed it on the carbs and so I took them off and did a thorough cleaning.  my cleaning was focused on those intake passages for the pilot circuit. I used the smallest two wires on the standard carb cleaning kits and reamed them clean.  carb 4  was the only one that seem to have significant blockage but it ran perfect before and after.  I sprayed all the orifices with Gumout and hit them with compressed air also.  I then reset all the float Heights to 26 mm.  now carbs number two and three run very rich and sooty where they were perfect before.   I should've mentioned also that I had 105 mains and 40 pilot jets both before and after and stock airbox. I just tried setting the fuel level extra low on carb number 2 at 28 mm below and it's still very swea I just tried setting the fuel level extra low and Carbone number 2 at 8 mm below and it's still very sooty.  I fear maybe I reamed out the air passages for the pilot circuit too much any thoughts? Could those two smallest wires have been too big?
« Last Edit: July 22, 2016, 02:43:53 PM by Wingnut74 »
74 CB360 - Winter 2014/2015 Project
74 CB750 - Winter 2015/2016 Project
70 Something TBD - Winter 2016/2017 Project

Offline flybox1

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Re: 74 CB750 Carbs 2 & 3 Sooty Rich After Cleaning
« Reply #1 on: July 22, 2016, 02:56:03 PM »
Clear tube test all carb bowls for accurate fuel level.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

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1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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Offline Wingnut74

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Re: 74 CB750 Carbs 2 & 3 Sooty Rich After Cleaning
« Reply #2 on: July 22, 2016, 07:59:26 PM »
Thats the funny thing. Carb 2 was super sooty and clear tube showed level at exactly gasket surface (pretty high), then dropped it to a super low 8mm lower and still super black sooty, so that made me think it can't be float level issue. Does that seem right?
74 CB360 - Winter 2014/2015 Project
74 CB750 - Winter 2015/2016 Project
70 Something TBD - Winter 2016/2017 Project