unauthorized throttle body sync - Yamaha FJR Forum : Yamaha FJR Owners Forums
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post #1 of 23 (permalink) Old 06-10-2017, 06:49 PM Thread Starter
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unauthorized throttle body sync

I am kind of thinking about taking a shot at performing the unauthorized (by yamaha) throttle body sync just to see if I get less vibes at around 4K revs. My '10 FJR seems pretty smooth overall but I just can't resist the temptation to see if I can make it even better. I don't have a four port sync tool but I do have a two port Harmonizer that I use to sync TB's on my flat twin '93 BMW. This is the procedure whereby you actually adjust the TB butterfly valves at idle after turning all four air bypass screws fully clockwise to their respective seats. I have used the two port Harmonizer to sync the TB's at idle with the brass screws by just referencing TB's 1,2,4 to TB#3 no problem. I'm too cheap to buy a 4 port sync tool.
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post #2 of 23 (permalink) Old 06-10-2017, 10:49 PM
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I think it would be unwise to try and sync with only two ports hooked up. I have not sync'd the FJR yet but have done many 4 cylinder bikes (I own 4 Z1900's)and the problem is there may be a slight change in the others as you change one.I am not sure if the same thing happens with a fuel injected bike but I would assume so. If this happens you coiuld make it much worse and it would be hard to correct once they get out of sync. I think you would want to view all of them.
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post #3 of 23 (permalink) Old 06-11-2017, 12:24 AM Thread Starter
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Originally Posted by cra-z1 View Post
I think it would be unwise to try and sync with only two ports hooked up. I have not sync'd the FJR yet but have done many 4 cylinder bikes (I own 4 Z1900's)and the problem is there may be a slight change in the others as you change one.I am not sure if the same thing happens with a fuel injected bike but I would assume so. If this happens you coiuld make it much worse and it would be hard to correct once they get out of sync. I think you would want to view all of them.
Thanks for that. I think you make a valid point. If this were to occur I would be up the proverbial creek. I think I'm going to resist the temptation to diddle with something that works either that or invest in a 4 port sync tool. Using the Harmonizer to sync each throttle body to #3 as a reference works alright but maybe not when it comes to the butterfly valves and the shared linkage assembly as found on the FJR.
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post #4 of 23 (permalink) Old 06-11-2017, 02:05 PM
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The FJR is so weird to me. I'm used to syncing 4 cylinder carbed engines everytime I do anything to the carbs including a clean and its always been done with a 2 gauge sync tool. However carbs 1 and 2 would be linked and 3 and 4 are linked with an additional adjustment to sync the two banks together using carbs 2 and 3 and always by adjusting the butterflies. Using the air adjustment screws seems so wrong and backwards to me and a good way to screw up A/F ratios... Getting used to Fuel Injection is going to take some time
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post #5 of 23 (permalink) Old 06-11-2017, 02:14 PM
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Carrying out this procedure is very straight forward, but impossible 2 at a time !
You need the 4 dials to ensure that they are as near to perfect as possible, although perfection is some times an impossibility !
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post #6 of 23 (permalink) Old 06-11-2017, 08:57 PM
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Originally Posted by JamesW View Post
I am kind of thinking about taking a shot at performing the unauthorized (by yamaha) throttle body sync just to see if I get less vibes at around 4K revs. My '10 FJR seems pretty smooth overall but I just can't resist the temptation to see if I can make it even better. I don't have a four port sync tool but I do have a two port Harmonizer that I use to sync TB's on my flat twin '93 BMW. This is the procedure whereby you actually adjust the TB butterfly valves at idle after turning all four air bypass screws fully clockwise to their respective seats. I have used the two port Harmonizer to sync the TB's at idle with the brass screws by just referencing TB's 1,2,4 to TB#3 no problem. I'm too cheap to buy a 4 port sync tool.
the ' throttle body sync ' is ONLY effective at idle
and the instant one cracks the to throttle up

that moment at transition if ALL Things are equal ......................
results in a smoooooooth throttle up

an ' even / equal ' idle for ALL cylinders
& a smooooooth thransition makes for a great ride

at 4000 rpm you are in an entirely different map
from the ECU & its being managed by the
O2 sensor
throttle position sensor
apparent load on engine
usually full ignition advance

after a compression test [ will usually attest to some differential in cylinders ]
which directly affects vibrations at speed

a - not unusual a valve adjustment [ valves may be in tolerance YET ALL 16 NOT exactly the SAME !!!!]
b - new spark plugs ......... ' indexed '

will mitigate most vibe issues
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post #7 of 23 (permalink) Old 06-12-2017, 12:04 AM
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I like that little tip about indexing the spark plugs, old school performance tip, +1
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post #8 of 23 (permalink) Old 06-12-2017, 01:36 PM
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Originally Posted by road1dog View Post
the ' throttle body sync (with the bleed screws) ' is ONLY effective at idle
and the instant one cracks the to throttle up

that moment at transition if ALL Things are equal ......................
results in a smoooooooth throttle up

an ' even / equal ' idle for ALL cylinders
& a smooooooth thransition makes for a great ride

at 4000 rpm you are in an entirely different map
The unauthorized sync will also set the throttle blade opening (Vacuum balance) above idle. After the initial TBS screw setting. Once cracking the throttle above idle speeds it does indeed change the vacuum balance and one can get the airflow(vacuum) balance improved quite a bit. In my experience 2 or 3 of cylinders have been fairly close initially and the 4th has been off by at least 10-15 % quite often. During this step it requires tweaking the throttle blade balance to get an even vacuum at 4k or your choice of cruise RPM. It has generally taken me 3 or 4 attempts to get both speeds to be balances at the same time.

Adding a simulated road load while performing this in gear, make the variance greater yet.

The additional above idle step has made a noticeable difference every time we have done it on an FJR.

Granted I am new to this forum , especially with the posts, but one of the other sites has several very detailed write-ups with pictures of what screws to turn for the throttle blade opening adjustments for the off idle adjustment.

NBB
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post #9 of 23 (permalink) Old 06-12-2017, 02:04 PM
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Originally Posted by NBB View Post
Once cracking the throttle above idle speeds it does indeed change the vacuum balance and one can get the airflow(vacuum) balance improved quite a bit. In my experience 2 or 3 of cylinders have been fairly close initially and the 4th has been off by at least 10-15 % quite often. During this step it requires tweaking the throttle blade balance to get an even vacuum at 4k or your choice of cruise RPM. It has generally taken me 3 or 4 attempts to get both speeds to be balances at the same time.



NBB
most engines at that speed are well into the ' torque curve '
at peak torque usually at ' full advance ignition '
resulting in the maximum ignition [ bang !! ] inside the cylinder

[ many mistake the event to occur at reedline ....]

4000 rpm has absolutely nothing to do with the idle
no less it has nothing to do with redline performance

so tuning at idle does NOT effect either
tuning specifically at 4000 rpm has NO effect at idle or redline
no less tuning WOT [ wide open throttle ] has NO effect at idle or 4k rpm

so im at a lost to comprehend what one might accomplish
the actual compression of each cylinder ..............SELDOM SAME ALL 4 cylinders
will be a greater factor than adjusting idle screws

[ a direct result of the ghost cylinder ................1 that fires directly after & beside
the prev cylinder at a distinct / evident disadvantage
no less harmonics in the inlet & exhaust tract present other quantifiable negatives ]

no less a accurate / blueprinted valve adjustment
will be a larger factor than adjusting idle screws
while 16 valves might be within operational tolerance
they are SELDOM accurately / exactly the SAME !!!!!

both compression + valves will attribute more to ' vibrations '
than the idle screws can EVER mitigate

no less over the overall life of an engine
while it in its CORRECT operational dynamics

you will NEVER have enough adjustment at the idle screws
to compensate for the ongoing realistic operational parametres
of the engine

ciao

good luck
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post #10 of 23 (permalink) Old 06-12-2017, 07:07 PM
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There's nothing nicer than a smooth engine. I can't believe that's not worth $80 to buy a 4 port
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