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Discussion Starter · #1 ·
Hey all,
So I have been having engine stutter issues on my 2016 FZ09. It usually comes on pretty aggressive when I slow roll the throttle and try to maintain speed. The bike tends to jerk forward a bit and then sounds like the engine cuts out and kicks back in. Very odd. Anyways, I’ve replaced the spark plugs to attempt to fix. No avail. I took it to Freedom Powersports and asked them to do a throttle body sync on it as I don’t think this bike has ever had one done. (9k miles currently). The guy told me Yamaha says to NOT do a sync on the throttle body. And they are not allowed to do those on FZ. Not sure how true this is, people Ive heard from say their bike has never ran smoother and better after syncing it up. Has anyone ever heard of this before? Yamaha not allowing TB syncs.
 

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I’m not, I’m in Georgia
The only reason I ask is because I have an old time bike acquaintance that works at a Freedom Powersports, I believe in Alabama. But my two cents is this...Throttle Body Syncs have been done by dozens here in .org-land.
 

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Discussion Starter · #5 ·
The only reason I ask is because I have an old time bike acquaintance that works at a Freedom Powersports, I believe in Alabama. But my two cents is this...Throttle Body Syncs have been done by dozens here in .org-land.
So you have never heard of someone not willing to do a sync on an FZ09? I thought it was weird he said Yamaha doesn’t want people doing it. I even asked, well how are you supposed to fix the cylinders when they get out of sync? And he said they don’t get out of sync. I laughed and told him to replace my O2 sensor and TPS lol
 

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Have you set up your suspension to your weight?
 

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The maintenance schedule for my 2015 FZ-09 called for a throttle body synch at the 600 mile maintenance and my dealer performed it.
 
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Discussion Starter · #9 ·
The maintenance schedule for my 2015 FZ-09 called for a throttle body synch at the 600 mile maintenance and my dealer performed it.
That’s what I thought. Not sure what freedom Powersports is talking about when they said they aren’t allowed to perform, per Yamaha.
 

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Find another mechanic who knows what he's talking about. Yamaha recommends regular syncing, and it makes a difference especially if your engine has become buzzy at highway speeds.

I just did my own, with help from a $100 manometer. Yeah you have to remove a few parts, but anyone with tools (and YouTube) can handle it.
 

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The throttle body sync only effects idle, so unless your problem is at idle, it will do nothing. It will not have any effect at any other throttle position. Will NOT reduce “buzzing” at cruising speeds, that is an urban myth.
 

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No argument that TB sync is done at idle, and primarily affects idle/off-idle transitions. But if it does "nothing" at highway speeds then I guess my bike didn't get that memo, because it's been running smoother ever since the sync.

I went looking for third-party corroboration of your claim but could only find you making the same claim in an older thread in this forum. Can you recommend a good link on this subject?
 

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Might be worth doing a compression check and valve clearance check, specially on the exhausts
 

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No argument that TB sync is done at idle, and primarily affects idle/off-idle transitions. But if it does "nothing" at highway speeds then I guess my bike didn't get that memo, because it's been running smoother ever since the sync.

I went looking for third-party corroboration of your claim but could only find you making the same claim in an older thread in this forum. Can you recommend a good link on this subject?
When you understand how the system works, you will realize that they have no effect once the throttle plates are opened a couple of degrees. They adjust how much air each cylinder gets at idle and has a slight effect when the throttle plates are just starting to open. The throttle plates are closed at idle and there is an air bypass port which allows air to bypass the plates at idle, the brass screws adjust how much air is allowed to bypass the plates. So you are correct it affects idle/off idle transitions but nothing else, as soon as the plates are open more that a couple of degrees they have no effect on how much air the engine is getting. The only other parts to the equation are fuel and timing which are controlled by the ECM, so turning those screws have no effect on either. Did you have some sort of vibration meter on your bike to quantify your statement about it reducing vibrations? The brain works in mysterious ways. If you feel less vibration then its a win for you.
 

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Hey, leave my brain out of this. It's got enough problems as it is :p

My assumption is that those bypass channels must have some effect at all RPM, since they're still flowing air in an altered ratio. I feel the difference on the highway, and not in the way that an Amsoil fan feels his hair growing back after a $50 oil change. This is real. And many other people report the same thing. Some of them even perform the sync at an elevated RPM, specifically to optimize smoothness at that RPM (not at idle).

Can anyone cite a credible third-party link on this topic?
 

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Air will flow in the path of the least resistance, when the plates are open enough to provide less resistance that the ports it will no longer flow through the port.

My
163708
 

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The bypass ports don't close, so they are still flowing air. The amount is the same but once the butterflies open the relative amount of air is much less but make no mistake, they are still flowing air.
 

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The bypass ports don't close, so they are still flowing air. The amount is the same but once the butterflies open the relative amount of air is much less but make no mistake, they are still flowing air.
And completely ignoring the laws of physics.
 

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When you close the throttle at any speed the air bypass is in effect, which is why you can get hesitation when you crack the throttle open and the TB's are out of sync. This can happen at any rpm.
And, the first time I did a TB sync, the engine was noticeably smoother because the TB's were a fair way out.
I'll rely on empirical evidence on this one.
 
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