Carb sync

[Heinno]

Hi All

I am planning a rejet for my Valk as I have installed a set of Cobra's. Once the rejet is done - is a carb sync automatically required, or would it depend on how the bike runs afterwards?

[Sigrún]

Hi Heinno!

I would say depends on the case. Mine had Cobra's on when I bought the bike, evidently re-jetted, and the carbs were all over the place. Pilot screws way off, gas mileage horrible and carbs badly off sync. Took me a bit of tinkering but now she's purring like a kitten. But putting in new jets do not automatically require sync if you're in with a bit of luck. IMHO

Cheers!

Orvo

[CajunRider]

From what I understand, the sync controls how much air is allowed through the carbs.  You're adjusting the butterfly baffle, not the fuel. 

With that being said, I'd imagine new jets wouldn't need a new sync... however, a good sync just to be sure wouldn't hurt. 

If you adjust valves, definitely a new sync is needed, as valves control air also. 

[Chiefy]

What are the symptoms that would make an experienced mechanic snap his fingers and say a bike needs the carbs sync'ed?

[Heinno]

What are the symptoms that would make an experienced mechanic snap his fingers and say a bike needs the carbs sync'ed?

Don't know - would like to find out.

[Heinno]

From what I understand, the sync controls how much air is allowed through the carbs.  You're adjusting the butterfly baffle, not the fuel. 

With that being said, I'd imagine new jets wouldn't need a new sync... however, a good sync just to be sure wouldn't hurt. 

If you adjust valves, definitely a new sync is needed, as valves control air also. 

The bike ran smooth with the stock exhaust. Now I added the Cobra's - still run smooth, but I want the lost HP back. So, the question is - if I just replace the jets, would this mean the bike needs a sync?

[ricoman]

What are the symptoms that would make an experienced mechanic snap his fingers and say a bike needs the carbs sync'ed?

Probably a definite lightness in his wallet.

[bigfish_Oh]

What are the symptoms that would make an experienced mechanic snap his fingers and say a bike needs the carbs sync'ed?

Probably a definite lightness in his wallet.

and knowing the fullness of yours

[98valk]

From what I understand, the sync controls how much air is allowed through the carbs.  You're adjusting the butterfly baffle, not the fuel. 

With that being said, I'd imagine new jets wouldn't need a new sync... however, a good sync just to be sure wouldn't hurt. 

If you adjust valves, definitely a new sync is needed, as valves control air also. 

The bike ran smooth with the stock exhaust. Now I added the Cobra's - still run smooth, but I want the lost HP back. So, the question is - if I just replace the jets, would this mean the bike needs a sync?

to get some of the HP back u need to let more air in by modifying the airbox and also using larger main and pilot jets and adjustable needles. then lots of tunning. Factorypro's kit has these mods for cobras, I have posted the results of the dyno work a few months ago.
If u are pulling the carbs out, its a good idea to sync them. if just removing the bowl covers and replacing the jets with the carbs in place, most likely don't need a sync. If u don't know the last time they were sync'd, then it would be good to do it.

[Ken Tarver]

just go ahead and do the sync......it's as fun as all the other stuff we do to our valks

[PhredValk]

You may never get all the HP back. Cobra and Two Brothers 6 into 6 pipes sound awesome, but you lose 5-8 HP and torq. When I put the stock exhaust back on (I bought the I/S with 2 bros on it; tons of fun in the city but I was sure I'd hate them on the hi-way after 5 or 8 hours) I noticed the bike got stronger and stopped popping on decel. Probably never re-jetted by the PO when he put the pipes on.
I'm seriously looking at the Q-Express glass pack mod on the Shoptalk page. Loud, louder and quiet on the hi-way with the silencers. Like 3 or 4 sets of pipes in one, and 20 minutes to swap it all out.
Fred.

[gregc]

Before you do any mods to the airbox, read about it on here.  Alot of people that have done anything to the airbox regret what was done.  The air box on the Valkyrie is pretty much a perfect design, only thing to change is the airfilter.

[Patrick]

How's the monster run ?? Does it idle smoothly and does the engine accelerate smoothly when lightly opening the throttle ?? If not, a carburetor sync could be in order.. It easy and fun to do,, and cheap.. A plain ole vacuum gauge works just fine..

[Heinno]

How's the monster run ?? Does it idle smoothly and does the engine accelerate smoothly when lightly opening the throttle ?? If not, a carburetor sync could be in order.. It easy and fun to do,, and cheap.. A plain ole vacuum gauge works just fine..

At the moment she runs fine - but I have not one the jet exchange yet - my question is, if one changes the jets - is a carb sync always required?

[GOOSE]

heinno....just changing the jets does not mean you will have to synch the carbs.  but if you replace those intake manifold o-rings/intake plugs/and or any hoses that might be, or were leaking, then you DO NEED TO RESYNC those carbs.

[Patrick]

I thought most fellas just adjusted or changed the needles when installing Cobra's..

[Heinno]

heinno....just changing the jets does not mean you will have to synch the carbs.  but if you replace those intake manifold o-rings/intake plugs/and or any hoses that might be, or were leaking, then you DO NEED TO RESYNC those carbs.

Thanks Goose - I understand