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Discussion Starter #1
I am having issues with syncing the carbs, I can get them synced at idle or they can be synced at 4000 rpm. Not both.

How in the world do you sync these things with only one screw?

I have looked to no avail about exactly how to sync these things, Does anyone have a clue?

Thanks.
 

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and the Adventure Cycle
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You did check THIS thread from the Vulcan Verses, didn't you?
It says the front cyl is the reference cyl, and adjustments are made only to the rear.
Other than that, I can't be of any more help. Sorry.
 

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hummm, not sure if a partially clogged jet would affect it... have you checked that?
 

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Discussion Starter #4
I have had issues util I pulled and cleaned the carbs 4 Times unti I got it to run smooth as glass.

Now I am sure there is a procedure that I am missing. There is only one screw so it would not matter which cylinder is reference as long as they are the same.

They use the front cylinder as reference for explanation, because you cannot adjust any air screws (there are none).

I am just wondering if anyone has actually done a sync and what procedure they used.
 

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Nope haven't done a sync, but I am going to try to get to it on Saturday... I will let you know what they do at the shop.
 

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Once Banned
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If you had used seafoam, you never would have had to pull the carbs.
 

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dta116 said:
They use the front cylinder as reference for explanation, because you cannot adjust any air screws (there are none).
Yes there are... idle air screws... they are under a lead plug
 

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Now what
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Sounds like you already have a manometer to measure the difference between the front and rear cylinder and you know how to read it, so I'll skip some of that. Set the idle speed first. Check the gauge readings. If the difference is less than 2 cm Hg, the carburetors are considered synched. If not, the carburetor butterfly adjuster bolt on the rear cylinder is adjusted. Turning it in will increase vacuum in the rear cylinder and turning it out decreases it. After the vacuum readings are close enough, the idle is checked again.
 

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Discussion Starter #10
Thanks Ironman, I have done exactly that....If I increase Idle to 4000 rpm, The sync is off by quiet a few inches (on a yard stick). So, I either set it for idle or set it for 4000...See my delima?

Thanks
 

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Now what
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dta116 said:
Thanks Ironman, I have done exactly that....If I increase Idle to 4000 rpm, The sync is off by quiet a few inches (on a yard stick). So, I either set it for idle or set it for 4000...See my delima?

Thanks
Clymer's says to just set it by the idle. No mention of checking it at any other speed.
 

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and the Adventure Cycle
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From what I've recently read, they only need sync'd at idle.
 

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Only speculating and thinking out loud here, but it makes sense to sync the carbs at idle and then to have it read different at higher rpms. At idle, fuel is being measured through the pilot circuit and usually you should be able to make small adjustments to the mix through the fuel mix screws. But at higher rpms, you are into the main jets and there are no adjustments you can make on the fly. I'd still think it would be closer when at higher rpms though. Although, maybe that is "close" for higher rpms.??

I know you don't make adjustments to the fuel mix (idle mix) screws during syncing, by the way...
 
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