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Throttle Body Syncro Guide.


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#1 spike240

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Posted 08 March 2019 - 09:55 pm

Anyone know if there is a guide or tutorial on the site. I have searched but found nothing so far. I don't have a manual.
Bike is TDM 900 and runs well apart low speed woes. Syncronising the TB is the only thing I haven't done.
Ta muchly.

#2 fixitsan

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Posted 09 March 2019 - 07:38 am

Anyone know if there is a guide or tutorial on the site. I have searched but found nothing so far. I don't have a manual.
Bike is TDM 900 and runs well apart low speed woes. Syncronising the TB is the only thing I haven't done.
Ta muchly.

 

 

Have you checked the CO settings first ? There is a guide for doing that somewhere...with the ignition off hold down both the select and reset buttons and wait till the display changes to 'DIAG', then pressing one of the buttons brings up 'CO' and the other button displays the CO values (been a while, so better check the JBX site for clarity).

 

CO means either carbon monoxide, or 'COrrection' I believe it is the trim value for each throttle body, at low speed and low load conditions. The bodies, and injectors, will have slight manufacturing differences, and the intake snorkels are different lengths, so the CO setting lets us get the same fuellng at both cylinders in those conditions, much like an idle jet adjustment worked on carbs.

 

The CO setting display will show two values, one for each cylinder. They are more often than not different, but can sometimes be the same. If they're both set to very high or very low values then they've probably been tweaked in the past. It is possible for them to be like that from the factory, in theory, but generally the values are usually below +/- 40, and often within a figure of 10 between both settings (example figures). Mine were 12 and 20.

 

An adjustment to these values is usually done to smooth out low speed running problems. The important thing to remember is that if you change them it is a good idea to keep the relative difference between both valuse, in my case the right hand figure is always 8 more than the left (just to accommodate those physical differences between the TBs

 

 

 

For actually balancing the throttle bodies, there is just one screw to turn, as far as i remember, and just like with carbs you should adjust it for best, smoothest idle


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#3 Rallyist

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Posted 09 March 2019 - 07:54 am

Look here http://www.tdm-yamah...t.org/?page=SYN


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#4 thelodger

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Posted 09 March 2019 - 08:37 am

Sorry this will not be helpful but I found I could not remove the rubber cap on the LHS ( from memory ) so
I couldn't even start the job !
 
Note the balance would have to be a clog out for you to notice any difference .

 
I found the one change which really made a difference to the low speed running was the air flap mod. 

Changing the CO settings might help a bit but without an exhaust gas analyser its guesswork. You can change it while the engine is running so with a lot of patience you might improve matters

#5 PeterM91

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Posted 09 March 2019 - 11:17 am

Hi guys! A few years ago I found a comprehensive tutorial on how to synchronise the throttle bodies on a FJR1300 (thanks to Fred W.).

Just subtract two cylinders and you can read it for a TDM900.

 

The point is that the procedure in the Yamaha manual doesn't take in account that the butterfly valves determines the synchronisation above 2000 rpm and not the air bypass crews.

 

Quote:

What's going on here is that the "official" Yamaha throttle body sync procedure, the one called out in the
Service Manual and specified as a "required" procedure at 4k mi. intervals, is simply an adjustment of the air bypass
screws at idle speed. These bypass screws have their primary effect on the cylinder vacuum at idle speed, and have very little to do with
how smoothly the engine runs at anything other than at idle or just above. As the throttle butterfly plates open, the tiny amount of air
contributed to the total intake by the bypass circuit becomes increasingly less significant, so that by the time you are at 3-4k rpm these
screws are pretty much insignificant. What is significant at larger throttle openings would be the relative angles of the throttle plates to
each other.

 

The complete procedure with some pictures: https://www.dropbox....UA_TBS.pdf?dl=0

 

I've done this a few times on two TDM's and it worked like a charm!

Less vibration and a smooth running at low rev's.



#6 fixitsan

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Posted 09 March 2019 - 12:54 pm

Hi guys! A few years ago I found a comprehensive tutorial on how to synchronise the throttle bodies on a FJR1300 (thanks to Fred W.).

Just subtract two cylinders and you can read it for a TDM900.

 

The point is that the procedure in the Yamaha manual doesn't take in account that the butterfly valves determines the synchronisation above 2000 rpm and not the air bypass crews.

 

Quote:

What's going on here is that the "official" Yamaha throttle body sync procedure, the one called out in the
Service Manual and specified as a "required" procedure at 4k mi. intervals, is simply an adjustment of the air bypass
screws at idle speed. These bypass screws have their primary effect on the cylinder vacuum at idle speed, and have very little to do with
how smoothly the engine runs at anything other than at idle or just above. As the throttle butterfly plates open, the tiny amount of air
contributed to the total intake by the bypass circuit becomes increasingly less significant, so that by the time you are at 3-4k rpm these
screws are pretty much insignificant. What is significant at larger throttle openings would be the relative angles of the throttle plates to
each other.

 

The complete procedure with some pictures: https://www.dropbox....UA_TBS.pdf?dl=0

 

I've done this a few times on two TDM's and it worked like a charm!

Less vibration and a smooth running at low rev's.

 

 

I always thought synchronisation was always about the valve flap angle. there normally isn't very much play in the linkages, or wear enough, to cause the flaps to be in need of adjustment

 

I use a very crude but still very effective way I was once shown, using 2 pieces of dowel or brass about 10mm in diameter....put one piece in the throat to hold the butterfly open and try sliding the other into the other intake throat under that flap....it should be a snug fit. if it's too loose or too tight you just need to adjust the synchronising screw to get them both parallel at that midway position. but there is a downside, which is if both bodies are manufactured at different ends of spec then when at idle and the valves are 'fully closed' the slight air leakage through each of the flaps is different, resulting in a rough idle. if that's the case it's probably best to adjust synch at the idle position for the most even running and you'll be pretty close


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#7 dandywarhol

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Posted 09 March 2019 - 01:33 pm

 

 

I always thought synchronisation was always about the valve flap angle. there normally isn't very much play in the linkages, or wear enough, to cause the flaps to be in need of adjustment

 

I use a very crude but still very effective way I was once shown, using 2 pieces of dowel or brass about 10mm in diameter....put one piece in the throat to hold the butterfly open and try sliding the other into the other intake throat under that flap....it should be a snug fit. if it's too loose or too tight you just need to adjust the synchronising screw to get them both parallel at that midway position. but there is a downside, which is if both bodies are manufactured at different ends of spec then when at idle and the valves are 'fully closed' the slight air leakage through each of the flaps is different, resulting in a rough idle. if that's the case it's probably best to adjust synch at the idle position for the most even running and you'll be pretty close

 

 

 

I always thought synchronisation was always about the valve flap angle. there normally isn't very much play in the linkages, or wear enough, to cause the flaps to be in need of adjustment

 

I use a very crude but still very effective way I was once shown, using 2 pieces of dowel or brass about 10mm in diameter....put one piece in the throat to hold the butterfly open and try sliding the other into the other intake throat under that flap....it should be a snug fit. if it's too loose or too tight you just need to adjust the synchronising screw to get them both parallel at that midway position. but there is a downside, which is if both bodies are manufactured at different ends of spec then when at idle and the valves are 'fully closed' the slight air leakage through each of the flaps is different, resulting in a rough idle. if that's the case it's probably best to adjust synch at the idle position for the most even running and you'll be pretty close

 

The old school method doesn't cut it when there are idle bypass systems. Here is how it's done as per the factory method 

http://www.tdm-yamah...ex.php?page=SYN


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#8 PeterM91

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Posted 09 March 2019 - 01:41 pm

 

 

I always thought synchronisation was always about the valve flap angle. there normally isn't very much play in the linkages, or wear enough, to cause the flaps to be in need of adjustment

 

I use a very crude but still very effective way I was once shown, using 2 pieces of dowel or brass about 10mm in diameter....put one piece in the throat to hold the butterfly open and try sliding the other into the other intake throat under that flap....it should be a snug fit. if it's too loose or too tight you just need to adjust the synchronising screw to get them both parallel at that midway position. but there is a downside, which is if both bodies are manufactured at different ends of spec then when at idle and the valves are 'fully closed' the slight air leakage through each of the flaps is different, resulting in a rough idle. if that's the case it's probably best to adjust synch at the idle position for the most even running and you'll be pretty close

You’re quit right with that. Both angles need to be the same.

As far as I know, synchronising these "flaps" was/is the main way to synchronise a carburettor engine. That is why:

  1. I first close the bypass screws (carefully!)
  2. then synchronise the middle screw (which connects both butterfly valves) with the contraption form " the old bugger": http://www.tdm-yamah...t.org/?page=SYN
  3. after that synchronise the bypass air screws the same way
  4. Done!

Actually, this is what I use:

Attached File  IMG_20190309_143221a.jpg   99.74KB   21 downloads

Attached File  IMG_20190309_143215a.jpg   100.03KB   1 downloads



#9 fixitsan

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Posted 09 March 2019 - 02:56 pm

 

 

The old school method doesn't cut it when there are idle bypass systems. Here is how it's done as per the factory method 

http://www.tdm-yamah...ex.php?page=SYN

 

 

I usually see the same results. I have vac gauges and have used a manometer..

 

Only in the idle position, when the valve position error forms a much greater proportion of the flow difference do you end up having to compromise

 

Assuming an error only in the idle position would you be better off adjusting for equivalence at idle to ensure a smoother idle ? I would prefer setting for a smoother running in the higher speed range because a rough idle is only noticeable at idle times, which is probably the least used rpm speed on any trip I make


You’re quit right with that. Both angles need to be the same.

As far as I know, synchronising these "flaps" was/is the main way to synchronise a carburettor engine. That is why:

  1. I first close the bypass screws (carefully!)
  2. then synchronise the middle screw (which connects both butterfly valves) with the contraption form " the old bugger": http://www.tdm-yamah...t.org/?page=SYN
  3. after that synchronise the bypass air screws the same way
  4. Done!

Actually, this is what I use:

attachicon.gif IMG_20190309_143221a.jpg

attachicon.gif IMG_20190309_143215a.jpg

 

 

There we go, never having had to do it on my bike i wasn't aware of the bypass screws. it's nice to have a manometer, but at a push you could set up for smoothest running couldn't you ?


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#10 dandywarhol

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Posted 09 March 2019 - 03:02 pm

I'd prefer a smooth idle on a twin


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#11 spike240

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Posted 09 March 2019 - 08:30 pm

Just turned tablet on.
Thanks everyone.
Better start reading those links.
Again - thanks for all the replies.

#12 spike240

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Posted 10 March 2019 - 07:33 am

Hi and thanks again.

Regarding the CO settings - I had a play with those when I first got the bike (nearly two years ago). I found it made little difference so left it as I found it.

What I did notice, back end of last year while doing the valve shims, the plugs were a beautiful colour.

The bike starts on the button even after a week or two, ticks over as it should and goes very well, so I am fairly happy with it. A racing friend of mine had suggested TB syncro to get it absolutely perfect around town.

So next time I have the tank up, I will probably have a look, but for now I'll just enjoy it.

I have saved & bookmarked all the tips, I especially like the FJR thread - makes a lot of sense.

ATB



#13 fixitsan

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Posted 10 March 2019 - 08:34 am

I'd prefer a smooth idle on a twin

 

 

Me too, oddly, despite all the  evidence being that you spend less than 1% at idle and you should therefore probably adjust for best mid range running.

 

Then again, low rpm vibrations can be the most violent I suppose.

 

Life is a compromise as usual !


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#14 fixitsan

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Posted 12 March 2019 - 09:20 am

A guy in a Facebook group just shared his experience of using a 4port version of one of these with a single vacuum guage. You can open a valve just enough to provide damping for the guage from intake pulses. https://rover.ebay.c...tm/302807201716

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#15 JBX

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Posted 12 March 2019 - 11:16 am

Omg, Facebook to the rescue...we are at a new level of expertise... :good:

Getting rid of the very strong admission pulses on the 9er twin engine is something more complicated than using a simple aquarium accessory.

One solution is to use the surge tank under the airbox, it becomes useless in case the air intake flap is inactivated and can be removed very easily, if you don't have access to a real pulse killer in the workshop.

It was specially designed to get rid of those pulses.

 

The synchro job is effective from plain idle rpm to around 2500rpm, so better have the job done properly.

 

 

 

 

Ahem... did you mean "gauge" ?  :)


Edited by JBX, 12 March 2019 - 11:18 am.

top_640.png

 

 


#16 fixitsan

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Posted 12 March 2019 - 02:36 pm

Omg, Facebook to the rescue...we are at a new level of expertise... :good:

Getting rid of the very strong admission pulses on the 9er twin engine is something more complicated than using a simple aquarium accessory.

One solution is to use the surge tank under the airbox, it becomes useless in case the air intake flap is inactivated and can be removed very easily, if you don't have access to a real pulse killer in the workshop.

It was specially designed to get rid of those pulses.

 

The synchro job is effective from plain idle rpm to around 2500rpm, so better have the job done properly.

 

 

 

 

Ahem... did you mean "gauge" ?  :)

 

 

What utterly wasteful snobbery :)


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#17 PeterM91

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Posted 13 March 2019 - 10:52 am

Getting rid of the very strong admission pulses on the 9er twin engine is something more complicated than using a simple aquarium accessory.

Not so complicated as it seems.

As I mentioned before, the use of two of these damping pots works really well!

It gives a steady level in both tubes.

attachicon.gif IMG_20190309_143221a.jpg


Edited by PeterM91, 13 March 2019 - 10:53 am.


#18 fixitsan

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Posted 13 March 2019 - 12:01 pm



Not so complicated as it seems.

As I mentioned before, the use of two of these damping pots works really well!

It gives a steady level in both tubes.

attachicon.gif IMG_20190309_143221a.jpg

 

We use almost an identical system in some of the commercial printing equipment I work on.

 

The other way to do it is to fit the small orifice restrictors which normally come with gauges, which are normally left in the box, then the damping happens between the orifice and the meter.

 

I've seen that some suppliers are instead providing small valves, like those you would find in small fluid line systems or even aquariums, to restrict the rate at which the needle responds. By setting the valve to a small partial open setting you emulate the orifice restrictors and the needle rises steadily instead of bouncing about.

 

[/url]gauges by Chris Barron, on Flickr">http://40402267223_2f7f1db0e5_b.jpggauges by Chris Barron, on Flickr


Edited by fixitsan, 13 March 2019 - 12:03 pm.

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