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Author Topic: Carbs not closing now  (Read 1214 times)

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Offline Dakotarider

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Carbs not closing now
« on: May 19, 2017, 04:56:24 PM »
 On my 78 cb750, I took the carbs apart to set float levels. Now my slides won't close far enough, see picture. There is also a gap on my idle speed screw now of about 1/8 of an inch. Any ideas? It sounds like the slides are bottoming out, but that's not the case.
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Offline TwoTired

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Re: Carbs not closing now
« Reply #1 on: May 19, 2017, 04:57:59 PM »
Check your choke and your fast idle cam operation.
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Lloyd... (SOHC4 #11 Original Mail List)
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Offline Dakotarider

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Re: Carbs not closing now
« Reply #2 on: May 19, 2017, 05:17:48 PM »
 They are working correctly and the fast idle cam isn't touching. I forgot to mention that I replaced the fuel tubes orings so I had the choke plates apart and the carbs separated to do  that. I didn't have to disassemble the choke Springs at all.
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Offline TwoTired

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Re: Carbs not closing now
« Reply #3 on: May 19, 2017, 05:22:02 PM »
Did you sync the carbs?

Are all the slides holding open?  Or, just one of them..?
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline TwoTired

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Re: Carbs not closing now
« Reply #4 on: May 19, 2017, 05:23:25 PM »
Did you re adjust the throttle cables?
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Dakotarider

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Re: Carbs not closing now
« Reply #5 on: May 19, 2017, 05:47:33 PM »
 All of the slides are equally open and the cables aren't attached. I did bench sync the carbs previously.  It just went back together differently this time. The throttle cables were tighter. That seems odd
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Offline Dakotarider

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Re: Carbs not closing now
« Reply #6 on: May 19, 2017, 05:56:18 PM »
 Maybe I'm wrong about everything I was looking at the intake side of the carbs thinking they should be tighter but on the engine side there is barely a light through the slide. Does that sound right?
 While we're on the subject of carb tuning can I sync the carbs without installing the airbox? I've got a vacuum manometer that I'll do it with.
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Offline TwoTired

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Re: Carbs not closing now
« Reply #7 on: May 19, 2017, 06:21:38 PM »
The bottom of the slides have one side (Engine side) lower than the other.  Forms a "mouth" on the air filter side, called a "cutaway".

Yes, carbs can be sync'd without the air box.  But, tuning is done with the air filter on.
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Dakotarider

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Re: Carbs not closing now
« Reply #8 on: May 19, 2017, 06:51:10 PM »
Perfect information thank you that will help getting things ready.
 How much should I torque the small not on my ignition here, see pic
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Offline Dakotarider

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Re: Carbs not closing now
« Reply #9 on: May 19, 2017, 08:52:19 PM »
That white haze is from the exhaust.
ITS ALIVE!!!!!!
I had put oil in the cylinders so smoke is fine for now.
Tomorrow I tune...
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Offline evinrude7

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Re: Carbs not closing now
« Reply #10 on: May 20, 2017, 06:13:43 AM »
Quote from: Dakotarider on May 19, 2017, 08:52:19 PM
That white haze is from the exhaust.
ITS ALIVE!!!!!!
I had put oil in the cylinders so smoke is fine for now.
Tomorrow I tune...

looking good.
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Offline Dakotarider

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Re: Carbs not closing now
« Reply #11 on: May 21, 2017, 07:46:57 AM »
I got the bike tuned yesterday. I don't think I've ever had a bike that was so responsive. Balancing is a must!!!!
This thing sounds soooo good and the throttle feels like butter.
Weird analogy.
Can't wait for a dry day to take it out!
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Offline drumstyx

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Re: Carbs not closing now
« Reply #12 on: May 21, 2017, 07:59:34 AM »
Quote from: Dakotarider on May 21, 2017, 07:46:57 AM
I got the bike tuned yesterday. I don't think I've ever had a bike that was so responsive. Balancing is a must!!!!
This thing sounds soooo good and the throttle feels like butter.
Weird analogy.
Can't wait for a dry day to take it out!

I'd love to hear what you did to make it so responsive. My '78 has some minor hiccups IMO. But then, when you say throttle response, I'm comparing in my mind to the fuel injected Vulcan 900 I owned a few years ago. I don't suppose it'll ever be that crisp.
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