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Author Topic: Won't start  (Read 849 times)

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Offline vistirus

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Won't start
« on: January 31, 2012, 10:52:49 PM »
I'm trying to bring back a '78 CB750K that has been sitting (inside) for 20 years. The tank is clean, fresh gas, new fuel filter and lines. I pulled the carbs and broke them most of the way down (didn't pull all the jets). Soaked in B12, scrubbed, and blown out with compressed air. Checked the float levels and bench sync'ed. Gas is going to the float bowls, but seems not to be going to the intake very well. It tries to start (ran for a few seconds) and fires right up on starter fluid (shuts down when that burns off). Carbs didn't look that bad (12,000 original miles on bike). Should I pull the carbs back off and tear them down completely? Also, having trouble with the hook up of the choke cable. Anyone have a picture of exactly how the two rods holding the choke plates and the springs go together?  Any advice would be appreciated.
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Vistirus
Dripping Springs,  Texas

Offline Danno

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Re: Won't start
« Reply #1 on: February 01, 2012, 02:21:07 AM »
you must clean all the jets and orifices and try to pull out the emulsifier tubes an on that model I believe there is an accelerator pump in one of the carbs that must be able to move and all the accellerator tubes have to be clear before it will run right
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when you own a motorcycle the wife does not have to find you handy she just has to find you

Offline scunny

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Re: Won't start
« Reply #2 on: February 01, 2012, 04:01:57 AM »
+1 on clean jets and emulsifiers, look under FAQ's, I think there is a great article by TT there.
these pics may help with that choke linkage.
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past-cb100,ts250,cb500,cb500,gs1000,gs650g.phillips traveller
present-CB 650 retro
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           XL125S[sold]
           MT50 (white)
           MT50 (red)[sold]
           KN250/XS400 project
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Offline scunny

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Re: Won't start
« Reply #3 on: February 01, 2012, 04:03:03 AM »
and 1 more.
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past-cb100,ts250,cb500,cb500,gs1000,gs650g.phillips traveller
present-CB 650 retro
            VTR1000F3
           XL250S riverbed rocket
           TS250[sold]
           TS185[sold]
           XL125S[sold]
           MT50 (white)
           MT50 (red)[sold]
           KN250/XS400 project
           XR/XL250 bitsa under construction
           SL100[sold]
           XL250R
           pedal(pub bike) leaks oil
my gallery http://gallery.sohc4.net/members/personal/scunny

Offline my78k

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Re: Won't start
« Reply #4 on: February 01, 2012, 05:57:24 AM »
remember that the idle jets pull out on these they don't screw out. Use a rag and vise grips and use a gentle twist and pull method. The rag will help you from butchering the brass jets.

Make sure you clean them thoroughly and run some wire through them and the little holes through the sides of the jet as well.

Dennis
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Offline vistirus

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Re: Won't start
« Reply #5 on: February 01, 2012, 08:13:33 PM »
Guess I know what I  will be doing this weekend.  Thanks very much to everyone  for the advice and , Scunny, really appreciate the  pictures.  Maybe I can figure out what I was doing wrong.


Vistirus
Dripping Springs, TX
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Vistirus
Dripping Springs,  Texas
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