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Author Topic: Question about 550 K4 and PD 46 carbs  (Read 1310 times)

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Offline Scott S

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Question about 550 K4 and PD 46 carbs
« on: July 07, 2011, 05:16:54 PM »
 Basically, how do you synch the darn things?

 I did a search here and looked into my (non-Honda) manual, but they all refer to the earlier carbs from the 500/550's. My manifolds don't even have the tapped holes for the tubes to thread into for a vacuum gauge set.

 I did see some mention of a non-movable #2 carb. Set #1 to match it, then #3 to match those, etc.
 Is there a way to use vacuum gauges or do you just bench synch them?

 I'll be doing a tune up on my '78 550K soon and I have a strong suspicion that the carbs are out of synch.
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Offline Bankerdanny

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Re: Question about 550 K4 and PD 46 carbs
« Reply #1 on: July 07, 2011, 05:39:36 PM »
The holes are in the carbs and covered by screws that you have to remove first. The #2 carb (2nd from left) has a fixed slide. You adjust the rest by taking off the top covers to get to the adjusting the screws.
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Offline Scott S

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Re: Question about 550 K4 and PD 46 carbs
« Reply #2 on: July 07, 2011, 05:51:10 PM »
 So, I saw some screws that I thought were air screws...between the carb body and the manifold boots. That's them? Will my tubes for the vacuum gauge fit them?
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Offline Bankerdanny

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Re: Question about 550 K4 and PD 46 carbs
« Reply #3 on: July 08, 2011, 07:30:11 AM »
The air screws are on the bottom of the carb, these are the screws to remove to synch
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Offline Scott S

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Re: Question about 550 K4 and PD 46 carbs
« Reply #4 on: July 08, 2011, 05:33:50 PM »
 Thanks, Danny. I'm more familiar with the CB500 carbs; you can see why I was confused. Especially since I can't seem to find much literature that pertains directly to this model.
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Offline Bankerdanny

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Re: Question about 550 K4 and PD 46 carbs
« Reply #5 on: July 08, 2011, 06:27:23 PM »
Get the factory manual from the thread at the top of SOHC/4 Bikes. There is a supplement towards the back for the 77-78 550's, including the carbs
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Offline Danno

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Re: Question about 550 K4 and PD 46 carbs
« Reply #6 on: July 08, 2011, 11:24:20 PM »
it would be much easier to sync thes carbs with a velocimeter type setup the meter goes over the end of each carb before the air cleaner then each carb is adjusted to the same velocity as #2 they dont like to idle without the air box hooked up just pick any idle point that works and make sure it stays that way during the test also adjusting without the tops on can cause another air leak making it hard to get them right with the vacuum gauge
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Offline Scott S

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Re: Question about 550 K4 and PD 46 carbs
« Reply #7 on: July 09, 2011, 03:47:40 AM »
 Bikerdanny, do you mind posting a link to that manual? I've been surfing the site looking for info and just haven't been able to find it.

 Danno, thanks for the info. I have a Uni-Syn that I use on my dual Webers (air cooled VW). That oughta work, huh?

 How close do you think I could get by bench synching. That always got me REALLY, REALLY close on the 627B carbs.
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Offline Bankerdanny

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Re: Question about 550 K4 and PD 46 carbs
« Reply #8 on: July 09, 2011, 03:45:08 PM »
It's at the top of the list of topics that includes this one, highlighted in pink, just go to page 1 of that topic and scroll down.
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Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200
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