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Is there a performance gain by syncing the throttle bodies?
Yes absolutely... but only if your throttle body isnt sync'd properly already.

They "should" be sync'd from the factory, but nothing is perfect off the production line, theres bound to be ones out there that would require a slight adjustment. It requires an expensive shop tool to do properly but if you look around on here and elsewhere you can find DIY instructions on how to make the tool.
 

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Discussion Starter · #5 ·
I can make the diy tool easy. The problem is how would I know how much to turn the screw to begin with?
 

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Discussion Starter · #6 ·
Does adjustong these screws to adjust the idling speed? because I turned them 2.5 turns from stock 1.5 turns and still, it idles the same.
 

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Does adjustong these screws to adjust the idling speed? because I turned them 2.5 turns from stock 1.5 turns and still, it idles the same.
If you follow the throttle cable to the rotating assembly on the bike, you can see a set screw that controls where the throttle idle is. It's surgically tiny, and a massive pita to adjust. And the bike has ISC so the ECU is looking for idle conditions, so it'll get upset if you play with the set screw too much.
 

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Does adjustong these screws to adjust the idling speed? because I turned them 2.5 turns from stock 1.5 turns and still, it idles the same.
Idle speed is controlled electronically through the ISC (Idle speed control) and can only be adjusted with a Factory Yamaha diagnostic tool. The screw Xorbe described Im guessing is a Throttle Stop Screw. Not idle adjustment. Hence why when you adjust it, the idle doesnt change because the ISC is compensating for the change you made to the throttle stop position. Once you adjust the screw past where the ISC can compensate you will start throwing codes and possibly run rough/not at all/lean etc.

If you fiddled with the Bypass air screws you WILL HAVE to resync your throttle body.

Service manual states to thread them in all the way to seated position then begin re-sync procedure.

On anything with electronic fuel injection, if its running fine, dont touch it. Unless you have the diagnostic equipment to track the changes you'll be going around in circles and likely making running conditions worse.
 

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Discussion Starter · #9 ·
I am trying to fix the engine not starting at first time after turning off after a ride. I have a diy manometer. Do I need to sync at idle or at a specific rpm? That's all I need to know.
 

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I am trying to fix the engine not starting at first time after turning off after a ride. I have a diy manometer. Do I need to sync at idle or at a specific rpm? That's all I need to know.
Some claim that the recirc canister contributes to this issue, if you are talking about the generic difficulty of restarting at gas stations (just hold the starter button down, don't "tap" it.)
 

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I am trying to fix the engine not starting at first time after turning off after a ride. I have a diy manometer. Do I need to sync at idle or at a specific rpm? That's all I need to know.
most likely your sparkplugs are causing hot starts or starting issues . everything else is controlled by the ECU. return the screws to the std position. you are SOOOO LUCKY they have a blue mark indicating the factory position
replace with Iridium CR8IEX i think is the correct code. when you get them take the screw on bit (top of sparkplug) where the lead attaches as you dont need them. if you dont you wont be able to attach the ignition lead
 

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Some claim that the recirc canister contributes to this issue, if you are talking about the generic difficulty of restarting at gas stations (just hold the starter button down, don't "tap" it.)
doubtful
the Idle speed control is a hose that runs from throttle bodies into the airbox etc and so does the crankcase breather, and air injection for exhaust . the recirc canister captures fuel vapors that's it
 
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