Sync'd my TB's today

I decided to do a little how-to in the process.

Be sure to add the restrictor tubes, otherwise the measurement bounces something fierce.

Untitled by camper4lyfe, on Flickr

I've got a Carb Tune II that I bought back a few years ago. It came with 2 sets of screw in adapters for cabs/TB's. I ended up actually screwing these into the extension tubes. It worked pretty well.

Untitled by camper4lyfe, on Flickr

Looks like it's time to sync 'em up.

Untitled by camper4lyfe, on Flickr

Idle's a little low

Untitled by camper4lyfe, on Flickr

All better

Untitled by camper4lyfe, on Flickr

Definitely need to be sync'd

Untitled by camper4lyfe, on Flickr

All done!

Untitled by camper4lyfe, on Flickr

I've never heard of this before. Can you explain what exacly this does, and what happens if you don't do it?

Kenward said:

I've never heard of this before. Can you explain what exacly this does, and what happens if you don't do it?

Click to expand...

It evens out the vacuum in the throttle bodies. It essentially sets the TB's so that all 4 cylinders are getting the same amount of air/fuel and making it run smoother.

If you don't do it, your fuel mileage will drop, and it won't run as well.

Nice. I see you can get the RPM as a digital number readout. Can this be done on the 2007+ gauge clusters anyone? I looked at the ECU codes and didn't see it there.

bd43 said:

Nice. I see you can get the RPM as a digital number readout. Can this be done on the 2007+ gauge clusters anyone? I looked at the ECU codes and didn't see it there.

Click to expand...

I haven't a clue, to be perfectly honest. I've never seen an 07+ in person. You may want to check your owner's manual rather than the ECU codes. That may tell you if you can do it or not.

I have one of those old school meters with the dials should work just fine I guess? I may do this next weekend while I am off.

bd43 said:

Nice. I see you can get the RPM as a digital number readout. Can this be done on the 2007+ gauge clusters anyone? I looked at the ECU codes and didn't see it there.

Click to expand...

Nope, not on the US models at least, just a needle (fairly accurate but not as accurate as the 04 digital readout, quite a bit larger and easier to see as well when under way thou). The digital gauge (LS) you can change to Kilometers or MPH, air intake temp vs water temp. See below picture:


04 Fizzer, out of curiosity, did you check them at 3-4k RPM's?

I found on my 07, same tool (Excellent tool, very easy to use and high quality), re-checking and adjusting up to 4K gets rid of most of the handlebar/seat buzz at 4k. I adjust them so their pretty much even at both 1300 RPM's and 4k RPM's, helps alot with ...

Kenward said:

I've never heard of this before. Can you explain what exacly this does, and what happens if you don't do it?

Click to expand...

Really??? Multi cylidar motorcycles have always needed this done since basically the dawn of, well multis... This includes carb based fuel systems too... My first carb balance was done on my 1978 Honda Hawk 400...

Actually, you have to have more than one carb to obviously sync them (IE Harley V-twin with one carb, or FI, there's nothing to sync).

I'm a little confused, why are people syncing a fuel injected system? The computer should be controlling all that air/fuel mix stuff at each cylinder? I'm not sure if anything has been done to my bike but it purr's at 1200-1240 at idle..........

GeneM said:

I'm a little confused, why are people syncing a fuel injected system? The computer should be controlling all that air/fuel mix stuff at each cylinder? I'm not sure if anything has been done to my bike but it purr's at 1200-1240 at idle..........

Click to expand...

Incorrect. The ECU controls the ratio based on the intake temperature at the air box for all of the throttle bodies together. Synching controls the vacuum in each TB so that it pulls the same amount of the air/fuel mixture.

04fizzer said:

Incorrect. The ECU controls the ratio based on the intake temperature at the air box for all of the throttle bodies together. Synching controls the vacuum in each TB so that it pulls the same amount of the air/fuel mixture.

Click to expand...

OK, so there is not an injector for each cylinder on these bikes?

GeneM said:

OK, so there is not an injector for each cylinder on these bikes?

Click to expand...

There is an injector for each cylinder, as well as a throttle body.

04fizzer said:

There is an injector for each cylinder, as well as a throttle body.

Click to expand...

Hmm, seems odd to me that the TB's need to be synced. One would think the ECU or computer would monitor the air/fuel ratio then on each cylinder.

I'm guessing previous owner must have done this on mine b/c it's runs very smooth and it's idle is perfect...

It's an interval maintenance procedure, something that should be done ever XXXX miles.

Where did you round up all that equipment, I'm guessing that's not something you can rent from AutoZone?

GeneM said:

Where did you round up all that equipment, I'm that's not something you can rent from AutoZone?

Click to expand...

Search "How to build your own manometer"....
Some forum members have built and sinc'd their TB's from this thread.

motojoe122 said:

Search "How to build your own manometer"....
Some forum members have built and sinc'd their TB's from this thread.

Click to expand...

Or drop $100 and get a Carbtune. Way easier, and you can actually quantify the vacuum rather than just level it out.

04fizzer said:

It's an interval maintenance procedure, something that should be done ever XXXX miles.

Click to expand...

I bought a TB tool from MSStore at 10K. Checked it and it was barely out of tune. Checked it again at 20K and it was fine. I'm at 32K now and I haven't check it in a while...

Good to keep an eye on it but I won't go too crazy. Bike run a bit smoother at idle. What I need to do is check if the flys are still synch. Like at 5K or something like that. I'll do that on my next tune up sometime next week... while I change the clutch

the trick here is that the ECU bases A/F ratio on the exhaust that has come from all 4 (you just have the 1 O2 sensor) - so while it'll lean out a rich mixture, it doesn't know which cylinder was the rich one, it'll cut them all the same amount - meaning an out of sync throttle body will still screw things up.