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Throttle Body TB Sync How-To

102K views 228 replies 99 participants last post by  RC. 
#1 · (Edited)
Here's a litte pictorial how-to on throttle body synchronization. Today was the first time I ever did this so I'd appreciate any comments from those in the know, especially on the last part that deals with the throttle lever gap.

Synchronizing the throttle bodies (TB) insures that the flow rate of air into each cylinder is identical. A number of undesirable symptoms occur if the TBs are not synchronized. These include a rough running motor with more vibration than normal, also power and gas mileage will be reduced.

Each TB has a small port at its base which allows measurement of the air pressure inside the TB. This pressure will be less than ambient due to the opening of the intake valves during the piston’s down stroke. On the SV1000 there is a single TB synchronization screw which simultaneously changes the position of butterfly valves in both TBs. When the air pressure is the same the TBs are synchronized. Static vacuum measuring devices such as a mercury manometer or air flow measuring devices like rotometers (ball in tapered tube) may be used.

The first step is locating the small ports at the base of the TBs. Both are visable when looking through the large triangle opening in the frame on the right side of the bike.

Note: This statement is incorrect and will be appropriately edited in the final version of the How-To.
 

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#52 ·
Went the grape juice route out due to not having tranny fluid readily available in the garage. I figured the contrast in color made it a suitable choice, the viscosity made it dance alot but I had no problems as it didn't leave a film behind in the tube while it was being pulsed around. After the use I just dumped the juice out and rinsed out the hose...enviromentally friendly I guess.

For the record though it worked out fine as it didn't foam, streak or cause catastrophic engine damage. I went even cheaper and used a 2x4 from the neighbors lumber alongside his garage and the contrast made it super clear and plain as day to see:)
 
#53 ·
TB sync

Great write up. The pics helped so much in trying to figure out what was what. It took me 30 minutes and lots of cussing to get the front cylinder vacuum port free!! :wallbash: One needs a combination of kids hands with a plier's strength!

Anyway, once that was done it was real simple to get the rest going. After 22,000 miles of only doing oil changes I was very surprised to find my TB's still perfectly synced (I say "still" because I have to assume they were before). I didn't have to touch the screw at all!
 
#54 ·
Great write up. The pics helped so much in trying to figure out what was what. It took me 30 minutes and lots of cussing to get the front cylinder vacuum port free!! :wallbash: One needs a combination of kids hands with a plier's strength!

Anyway, once that was done it was real simple to get the rest going. After 22,000 miles of only doing oil changes I was very surprised to find my TB's still perfectly synced (I say "still" because I have to assume they were before). I didn't have to touch the screw at all!
You need a set of long needle nose pliers... I have a whole set of them and I never even stick my hands in the frame... I now have hoses on the nipples so to facilitate checking it.:supsmiley
 
#56 ·
My bike had a big service last week and I asked them to look at the throttle bodies and balance them at the same time as adjust the valve shims as I didn’t get time to make my own manometer.
The bike had done 24,000 miles now and both shims and bodies were perfect not a bit out after 3 years of hard use.

Service cost was £122.10p and I got a new DL1000 Vstrom to play with for two days.:)
 
#57 ·
Did you get a report from the mechanic listing the clearances on all eight of the valves? I got mine checked last time at 22K miles and was told all the valves were still in spec but two were right at the edge. I'm going to adjust the clearances myself at the end of the year and now I wish I had received some type of written report from the shop. It would be nice to know how much things are changing with miles ridden. If I ever bring the bike back to the stealers (which I'm not planning to) I'll ask for a written report up front.
 
#59 ·
For the synch, I removed the PAIR with Chewy's kit, and installed BMW vacuum plugs (shaped like a pear) without any clamps, so it takes me all of 2 seconds to remove both. Even with the engine hot, I can get my hand in there without burning myself. The less hoses, the better.
 
#60 ·
Throttle body synchronising

Hey: thanks to Bayou Boy for the pictorial and the how to on synching. I read it up, did the mod to extend the test ports, and got the job done.
I bought a twin max electronic synchroniser: I can't remember where I got it online, but you can do a search and find it. This thing really works well. It's electronic, runs on a 9 volt battery, and you simply hook up to the test ports, turn on the power, adjust the sensitivity to max, zero the meter, and then start the bike up, with the sensitivity set down to min. Then increase the sensitivity and check the balance on the meter. I messed around with it for a while, shutting the bike off and readjusting the zero a couple of times to make sure I had it zeroed properly. Thje sensitivity adjustment dampens out the power pulses from the cylinders, but I found the higher the sensitvity, the more accurate you are in balancing the TB's. However with the sensitivity set at about 3/4 the pulses are dampened out enough to read it accurately.

My bike was off just a little, I think about one unit, but all I had to do was barely touch the adjusting screw to bring it back in to line. It would appear to me that the adjustment is so sensitive, I can't imagine how it wouldn't get out of adjustment just by normal riding. I checked the balance all the way up to about 5,000 rpm and it seemed to stay pretty close to zero, just moving one point of a division each way up and down.

I would really recommend the twinmax. You can use it on a four cylinder bike too, you just adjust each cylinder in relation to the master cylinder, which on the SV is #1. On a honda 750 nighthawk it's number 2. I think I paid $69 for it online brand new.

Cheers
John.
 
#61 ·
Good deal, never seen a meter like your describing. Sounds like its a dual electronic vacuum gauge with storage and averaging capability - sweet. And no danger of sucking grape juice into the engine :bigclap: .

Can you post a pic of the device?
 
#62 ·
My bike has been running rather roughly so I thought it was about time I synchronised the TBs, it's taken me about two hours and I still haven't put everything back together.

I made a simple manometer with some fish tank tubing, a piece of wood, some sticky tape and some ATF. I decided to remove the airbox as I couldn't see how I could get at the front TB nipple and had a few problems - the IAT sensor coupler wouldn't come apart so I left it connected with the airbox hanging down, and I had to pull the hoses off the PAIR so that I could raise the airbox and get at the PAIR mounting screws. One advantage to removing the airbox is that I can now see the infamous green connector that has been causing so much trouble for some people.

When I attached the manometer and started the engine, there was a large pressure difference, which explained the rough running. I then turned the adjuster a bit too far and sucked out all the ATF, it made the engine smoke a bit. Refilling the manometer and getting rid of bubbles took quite a long time, sucking and blowing seemed to work quite well. The second time I was a lot more careful, only making very small adjustments. I got it right eventually, but it was very fiddly and took about 20 minutes.

When I put everything back tomorrow I'll leave a small length of tubing attached to the front TB nipple, with a plastic joint in the free end sealed with a screw and some sealant. The rear TB nipple is the connection for the Scottoiler.

I think I'll buy a differential pressure transducer, amplify the output with an op amp and use a micro-controller unit (MCU) to display the signal in some way (outputting a tone to an earpiece might be a good way, with the tone decreasing in frequency as the balance improves - perfect balance indicated by no tone). The MCU can also do some simple signal processing to remove the fluctuations. The whole thing should cost about £20 to make, more expensive than the manometer but much easier to use. I've got a free PSOC development kit coming from Cypress (normal price is $99), the PSOC MCUs include op amps so one of those would be ideal for this application. I develop embedded systems for clients, this should be quite straightforward.

Leon
 
#63 ·
Hey John, I also have the twinmax, and it's great. One caution though: remove the light inside the unit man. Besides eating the battery, it causes unwanted fluctuation as the light heats up things inside. This is a very well known fact that BMW riders found. You can buy them cheap from BMW riders who sell their twins; check their classifieds.

Hey guys, why mess with hoses if you remove the PAIR? I just removed the clamps from the nipples and put them back (well, actually replaced them with oval ones which are much easier to pull). I can remove them in 5 seconds by sticking my hand in there, even with the engine hot. I posted pics a while ago. Can find the thread if somebody wants to see them (can't post them again, as you know). Later.
 
#64 ·
I put everything back together first thing this morning and have just been trying it around town. It's running perfectly now - no vibration and it accelerates much more cleanly from low speeds. I connected a short length of tubing to the front TB nipple and plugged the end; the next time I need to do the job it should only take me a few minutes.

Leon
 
#65 ·
Just applied this FAQ to my bike. Used my own homemade manometer made of electrical tape, some clear plastic tubing I had laying around, and an empty cardboard box, with a bit of synthetic oil for the working fluid. At 15,000 miles, it was WAAAYYY off, as one might expect. But now it's smooth as silk again :supsmiley:

So I say THANKS FOR THE FAQ!
 
#66 ·
TB Sync port caps

While you're busy checking the TB sync and thinking about that TPS adjustment - don't forget to check the condition of the rubber caps, vacuum tubing, and connectors. Even a small hole or tear can throw things off balance.

Couple of days ago I noticed my SV started running rougher and the idle was drifting. As part of my inspection, I decided to check the TB sync. Found the rubber cap for the TB port (back cylinder) had dried out and cracked allowing a vacuum leak.

Some times it's the little things that really screw with you...:disgust:

I purchased a 5 pack of vacuum caps at local auto parts store for under $2.00. Replacement caps are longer (but easily trimmed) and have thicker sidewalls. Installed the new caps and the bike runs normally again.
 
#67 ·
Thanks for the excellent write-up Mark (bayouboy). It made synching my TB's nearly dummy-proof (e.g. even I could do it). Russ, (OBSOB) I used your value approach to make a manometer using ATF and it worked like a charm. I did drop the front vacuum cap while trying to get it back on never to be seen again, or so it seems. It may be somewhere in the engine someplace. I rocked the bike and tried tipping it over to either side almost till the pegs touched and nothing fell out. Oh well, .99 cents later I had a new cap back on and she's ready to ride (after it quits raining). Also, I had to get some longer needle-nosed pliers which made a LOT of difference.

Question: After removing the manometer, I started the bike up with only the rear vacuum cap on and the front missing thinking that it might vibrate out so I could find it. The idle went from 1,300 (which I set it at during the synch) to 2,000+. I adjusted the idle with the front cap missing, bought a cap and put it on. Both caps on, the bike's idle went almost to 1,000...so I adjusted with both caps in place. Will I have to synch the TB's again to make sure they were not affected by the idle adjustment? It seemed that the slightest movement of the idle or the TB adjustment screw made the levels of the cylinders way off.
 
#68 ·
Also, I had to get some longer needle-nosed pliers which made a LOT of difference.

Question: After removing the manometer, I started the bike up with only the rear vacuum cap on and the front missing thinking that it might vibrate out so I could find it. The idle went from 1,300 (which I set it at during the synch) to 2,000+. I adjusted the idle with the front cap missing, bought a cap and put it on. Both caps on, the bike's idle went almost to 1,000...so I adjusted with both caps in place. Will I have to synch the TB's again to make sure they were not affected by the idle adjustment? It seemed that the slightest movement of the idle or the TB adjustment screw made the levels of the cylinders way off.
The pliers make all the difference!

You shouldn't need to reset the TB's...
 
#71 ·
Here are a couple pictures of my homemade u-tube manometer. It is very similar to others shown on this thread, but I thought I would list a couple more tubing sizes that work. It is clear vinyl tubing with automatic transmission fluid inside. The larger tubing (the u-tube) is 3/16" I.D. and 5/16" O.D., 12 feet long. The smaller extension tubes are 0.170" I.D. and 1/4" O.D., each 4 feet long. They fit over the TB nipples nicely with an airtight seal, and the other end is forced into the larger tubing, also making an airtight seal (as shown in pic #2). I did not use any type of measurement scale (yard stick) since the only goal is to get the two columns of liquid at the same level. The manometer worked great.
 

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#72 ·
This kills me. I just paid the bike shop to do the TB sync because I didn't want to make any mistakes having never done this before. Had I read your tutorial first, I would have been much more comfortable getting in there on my own!

I will never pay before checking this site again!
 
#75 ·
Hope one of you cleaver chaps can help here...

1... How the hell do you get the balancer (manometer) rubber hose onto the front TB without taking the air box off.

2... What do I adjust to achieve the correct balance of the 2 TBs.

3... Do I go up or down the scale on the balancer (manometer).


First time I've had a go at syncing the TBs, got myself one of those Morgan carbtune's and I'm getting confused already....:crazy:
 
#76 · (Edited)
1. I don't think removing the airbox would actually help. The rubber caps on the vacuum taps are under the throttle bodies. You have to reach through the trianglular hole in the frame, squirm, and swear a lot. It might be helpful to find someone with small hands. Do you have a little brother? It IS difficult. So don't think you are doing it wrong just because it isn't easy.

2. perhaps you should review this thread.

http://www.sv-portal.com/forums/showthread.php?p=134262#post134262 EDIT: WRONG LINK, THIS IS Throttle Position Sensor Adjustment, not Throtttle Body Synch.

3. Up? Down? You do whatever it takes to make the vacuum of the two bodies MATCH. So pretty much, one will go up while the other goes down. So you need two manometers, or a differential manometer that compares the vacuum level of the two. Many folks on the forum have had a lot of succes by choosing not to buy the fancy expensive vacuum balancer tools and instead just spent $3 on some clear Tygon tube and a little Automatic Transmission Fluid, or perhaps the occaisional slug of Welches Grape Juice.

http://www.sv-portal.com/forums/showpost.php?p=317134&postcount=33
 
#77 ·
1. I don't think removing the airbox would actually help. The rubber caps on the vacuum taps are under the throttle bodies. You have to reach through the trianglular hole in the frame, squirm, and swear a lot. It might be helpful to find someone with small hands. Do you have a little brother? It IS difficult. So don't think you are doing it wrong just because it isn't easy.

2. perhaps you should review this thread.

http://www.sv-portal.com/forums/showthread.php?p=134262#post134262

3. Up? Down? You do whatever it takes to make the vacuum of the two bodies MATCH. So pretty much, one will go up while the other goes down. So you need two manometers, or a differential manometer that compares the vacuum level of the two. Many folks on the forum have had a lot of succes by choosing not to buy the fancy expensive vacuum balancer tools and instead just spent $3 on some clear Tygon tube and a little Automatic Transmission Fluid, or perhaps the occaisional slug of Welches Grape Juice.

http://www.sv-portal.com/forums/showpost.php?p=317134&postcount=33
Thanks for the info willie ... Yep sure is fiddly to get the hoses on ... I reviewed the thread for the TPS adjustment that's my next job .. but as I'm attempting to sync the TB's I'm not sure if I need to adjust both TB's or is the front one fixed and just adjust the rear one.....:confused:
 
#78 ·
DOH !

I linked to the wrong thread #2. Sorry Throttle Position Sensor adjustment is a good thing to do, but it was NOT what you were asking about.
 
#81 ·
#84 ·
Success.... TBs in perfect balance managed it with the airbox in situ, got my lad to get his little hands in to fix on the manometer tubes that are now a permanent fixture .... Thanks to Bayouboy for the how to with pictures, and of course Chainsaw for his last minute help...:supsmiley

TPS next..... :eek:hmy: :confused:
 
#88 ·
That hose should connect to the Intake Air Pressure (IAP) sensor, which is the sensor that is on one of the exterior back corners(2 of them on the '05+)of the airbox affixed by a screw. There is also wires and connector plugged into the sensor as well. Probibally got disconnected if you removed the airbox.

Has you bike been running with this disconnected? It will run, but would have had a FI warning light and code.
 
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