How bad does engine run before throttle body re-synch?

[xlxr]

Question ... How much worse does the engine feel when throttle bodies need to be synched?  I have read some guys says it runs better after re-synch, but can you tell before re-synch because the engine starts to run rough?   I have 5,000 miles on my bike, only engine mod was 2WDW ECU reflash at 300 miles. My engine runs so good from start up and beyond, I don't think it needs to be re-synched, yet.  I'm not sure how long I can get away with the "if it ain't broke, don't fix it" philosophy.
 
 
I had a 4 carb bike back in the 90's that I synched a few times, so I understand the basics, and will be doing the re-synch myself.
 

[nsmiller]

If you've not done it at all since purchasing the bike, I'll put a 6-pack of your favorite beer on the fact that your throttle bodies are outside of spec (10 mmHG difference). As far as how noticeable it is, it varies and depends exactly how out of sync they are. I would say it is almost always noticeable if they are out of sync. Slightly out of sync means a small change in engine smoothness. The further out of sync the greater the vibrations you'll feel in handlebars and throughout the bike. Doing the sync yourself is not very hard. Check out my DIY video:
 

[skipperT]

NS makes some good points. IMHO it all boils down to a couple things: how thorough you are about performing maintenance procedures and how sensitive you are to the operation of your bike and how it's running.
 
Can I always tell when I've synced the TB's and they were slightly off and now they're perfect? No, not always.
 
But I feel better knowing it's been done because that's how I roll.
 
Truth is, every rider is different. And every engine is also different, they might be manufactured to certain tolerances and specifications - but each one has the potential to wear a bit differently.
 
Do what makes you happy.
 
Your carbed bike from the 90's certainly benefitted from a sync every 4K or so... I don't think anyone would debate that.
 
Another data point: did you know that Honda NEVER recommends a TB sync on any of their FI bikes as part of regular maintenance?
 
Skip
 
 

[DavidS]

When you start noticing the engine running rough or uneven, look at the video nsmiller provided and do it. If it is running ok, and you aren't experiencing rough idle, wait a bit longer...
 
I have 5K on mine as well, and I still haven't felt the need to do the synch

[DavidS]

And when you do check them, put in longer hoses that you can check without taking the tank off next time. You won't be able to adjust anything, but you won't have to do all that work just to check if they are ok. Only if you know they need adjusting.

[xlxr]

Thanks for the responses. As the miles stacked up, my engine actually smoothed out quite a bit. I'll probably just hold off re-synching for awhile.

[2and3cylinders]

My FJ09 also has about 5,000 and not yet had a TB sync. Initially, within the first 2,000 miles it seemed to have intrusive vibration at certain road speeds but at idle it was, based on my admittedly unfamiliararty with a triple, OK. I have installed Kev's O2 Controller.
 
However, since it has presumably now worn-in (I don't like the term break-in), the objectionable vibration has all but disappeared. When running at the most efficient RPM at a given speed per the MPG reading and ECO indicators, I know it without even looking by a mild coarseness felt in the bars and a tone heard, which IMO is a good thing.
 
Could it be my FJ TBs were out of sync and as things meshed together over the miles married into sync?
 
Also, do others feel and hear the coarseness I do when presumably the engine is operating most efficiently??

[nsmiller]

It drives me nuts knowing that something could potentially be out of spec on my bike, regardless of whether it matters in the grand scheme of things or not. You guys that wait 5000 miles to even check your throttle bodies are nuts in my opinion, just because the mere possibility drives me insane. I don't personally believe your throttle bodies will just wear in if ignored. They are set to be in sync at the factory and as the engine wears in they fall out of sync. The screws on the throttle bodies just don't turn on their own, and the engine doesn't wear in such a way as to match what the throttle bodies are set to.
 
I've sync'd quite a few throttle bodies, and never have I met a bike that had never had the service performed that was within spec.

[estell]

I synched my throttle bodies at 5200 miles. It needed only a small adjustment, and I couldn't tell the difference in the way it ran afterwards. I didn't think it was worth the effort.
 
Here is the interesting part. You synch the throttle bodies at idle speed. If you rev it up to 3000 rpm, then the three cylinders are way off. Since you never ride at idle speed, your throttle bodies are always out of synch while riding. So what difference does it make if they are a little off at idle, when they are way off while riding?
 
Sorry, nsmiller, I hope you aren't going to lose sleep over this.

[britelitebob]

Well you can add me to your list of nuts since I haven't synced mine, I guess I've just been having too much fun riding it.

[DavidS]

I synched my throttle bodies at 5200 miles. It needed only a small adjustment, and I couldn't tell the difference in the way it ran afterwards. I didn't think it was worth the effort. 
Here is the interesting part. You synch the throttle bodies at idle speed. If you rev it up to 3000 rpm, then the three cylinders are way off. Since you never ride at idle speed, your throttle bodies are always out of synch while riding. So what difference does it make if they are a little off at idle, when they are way off while riding?
 
Sorry, nsmiller, I hope you aren't going to lose sleep over this.

I've heard of other folks synching at 3-4K rpm to solve that problem. I'm not sure if that causes other problems, and honestly, haven't given it too much thought since I haven't done mine yet.

[toast]

For what it's worth, my bike idles smooth as butter, throttle roll on is smooth (I also have the ecu flashed) and I'm almost to 20K miles and I haven't synced my throttle bodies once. I have never felt a difference since I bought the bike and I ride everyday, so I haven't done it.

[nsmiller]

I synched my throttle bodies at 5200 miles. It needed only a small adjustment, and I couldn't tell the difference in the way it ran afterwards. I didn't think it was worth the effort. 
Here is the interesting part. You synch the throttle bodies at idle speed. If you rev it up to 3000 rpm, then the three cylinders are way off. Since you never ride at idle speed, your throttle bodies are always out of synch while riding. So what difference does it make if they are a little off at idle, when they are way off while riding?
 
Sorry, nsmiller, I hope you aren't going to lose sleep over this.

To be clear, I'm not implying that if you wait to sync your throttle bodies you are damaging your machine. It probably has to do with the fact that I enjoy working on my vehicles almost as much as I enjoy driving/riding them. That probably has something to do with why I own 6 vehicles for only me and my wife... just can't quit buying cars and bikes for cheap and fixing them up.  
When I sync'd my wife's FJ-09 throttle bodies I sync'd them at idle, and then rev'd the engine to ~5K and they were still in sync. You just have to be steady on the throttle and give the vacuum a moment to stabilize at that speed. You can kind of see what I mean at the very end of my DIY video.
 
Don't worry, I'm not likely to lose sleep over the condition of your throttle bodies, nor the ugly purple cat in your profile pick. (rofl)

[estell]

When I sync'd my wife's FJ-09 throttle bodies I sync'd them at idle, and then rev'd the engine to ~5K and they were still in sync. You just have to be steady on the throttle and give the vacuum a moment to stabilize at that speed. You can kind of see what I mean at the very end of my DIY video. 
Don't worry, I'm not likely to lose sleep over the condition of your throttle bodies, nor the ugly purple cat in your profile pick. (rofl)

I haven't seen your video, but I may watch it now to see how you got it to stay in sync. 
And the purple powercat is ranked in the top ten of college football's best logos. See it here. 

[nsmiller]

When I sync'd my wife's FJ-09 throttle bodies I sync'd them at idle, and then rev'd the engine to ~5K and they were still in sync. You just have to be steady on the throttle and give the vacuum a moment to stabilize at that speed. You can kind of see what I mean at the very end of my DIY video. 
Don't worry, I'm not likely to lose sleep over the condition of your throttle bodies, nor the ugly purple cat in your profile pick. (rofl)

I haven't seen your video, but I may watch it now to see how you got it to stay in sync. 
And the purple powercat is ranked in the top ten of college football's best logos. See it here. 

Its not documented extremely well in my video, but if you want to see what I mean skip to 27:54. 
In order to not get too far off topic, I'll just simply suggest you go to Google and do a search for 'Most Dominant Mascot on Earth'. (All in good fun) In reality, there are much, much worse teams you could be a fan of than the Wildcats. For example you could be a Hawkeye. Thank goodness that's not the case.