How to synchronize your throttle bodies.

A TB synch will make your engine run smoother and happier. If your bike is old or you've adjusted the valves, it's probably past time that you do this.

These instructions are specific to the FZ6, but you can use the general technique on any bike with multiple throttle bodies or carbs.

Category:

Autos & Vehicles

Tags:

• throttle
• body
• synch
• carb
• tb
• sticks

[stogierogy]

Im new to this and want to try. How do you know what hose goes to which hose on the bike? I realize you said the pink band is for cylinders 1 and 4 but how do you know where all 4 individual hoses go? I have an FZ6 as well.

Thanks and great video.

[ElQuesoGuapo]

The cylinders are numbered 1-2-3-4 from left to right as you're sitting on the bike. Hoses 1 and 2 are on the left, 3 and 4 are on the right.

Connecting them in order is mainly important to prevent your confusion. If you hook them up in 4,1,3,2 or whatever order you want, you can still get a good synch, so long as you remember which is which when making adjustments.

My memory sucks, so I hook them up in order.

[JooKed]

Is it possible to sync them to the point where idle and 4k are the same? It almost sounds kind of cheap knowing that the bike isn't running 100% at idle but 100% at 4k or vice versa. If its possible to get thole whole range of rpms sync'd then wouldn't that be ideal? or not possible?

[ElQuesoGuapo]

You'd have a hard if not impossible time making them synch at both idle and higher revs. The differences show up because despite the best manufacturing practices, there will differences in parts which add up to differences in the behavior of each air intake. The synchronizing is designed to account for this and other factors such as compression differences, valve differences, and the position of each cylinder's intake in the airbox. All of that makes a difference.

[ElQuesoGuapo]

Don't think of it as the engine not running at 100%. That's not how it works. Think of it as some cylinders pushing harder than others because they're getting more air flow. Synchronizing gets the cylinders working at the same level of effort, which reduces vibrations and makes the bike sound and feel better.

You'll never get the engine synched perfectly at all throttle settings and RPM's. The best you can do is pick the range where you want the best behavior and target that.

[blk600cc]

Great video. My 04 R6 runs perfect but it does have 25K miles on it. the bike is getting the valves adjusted this week and then I plan on synching the throttle bodies. What mileage they should be synched at? Also, from a 1-10 rating (10 being the hardest), how hard is this to do by yourself or with the help of a friend? I do have mechanical experience but I just wanna be sure this is a job someone like myself can do. Appreciate it, look forward to your response.

[ElQuesoGuapo]

It's about a five. If it's your first time, make note of where the synch screws are set now.  That way if you decide that you've messed things up, you can easily go back to the old settings.

[defkon99]

got me on the last one! great video!

[serchmarc]

how do you know the 1st vaccum you have from your syncros is the correct 1,you are just matching each other ,you dont have a value?or you have to have the manual to chek the nominal value from the factory and then regulate the carbs..and is pretty interesting how 1 and 4 has more vac and 2 and 3 less but match eachother at 4000rpm thats defenitly a factory manual recomendation.i man do you have some zx7r on sell or a friend thats sell 1

[3ald3eaver]

@oboi2104 +1

[TroyaE117]

You are right about synchronising at highway revs. Better still is to do it on a dyno, so that you are at highway revs AND under load. Not may of us have a dyno though.

I tried recently to balance the carbs on a two cycle Suzuki GT 500A. It was very difficult. The vacuum was so low that I had to rev it like crazy 6000 rpm, to get a reading on the Morgan carbtune system.

[oboi2104]

"The red bikes are faster" : HONDA FTW

[blunt2544]

It should be against the law to not have your carb synced i just did mine for the first time in about a year and my god its a new bike to me

[redoctoberz]

You don't adjust the throttle plate position on the FI FZ6. The screws adjusted in the video do not touch the throttle plates. You only adjust the idle air circuit- that is why Yamaha says to only adjust it idle.

[carsnwomen91]

seriously? ur telling me? have u even seen my videos before u judge u don't even know what the tool is called. its called a manometer and it measures vaccum irregular to what kind of fuel delivery system. by sync'ing the throttle bodies ur essantially making sure that that each throttle plate/butterfly is opening at the exact same time equally. its the same on a carb. they too have butterflies or slides). ur lesson for the day. either learn something or ask or keep ur mouth shut. :)

[lvizzle5150]

why would he use carb tune on FI? seriously dude c'mon

[carsnwomen91]

where did u get the 4 cyl sunc tool? and u were adjusting on the fz6 that was FI or carb?