The Really, Definitely Completely Un-Authorized TBS

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Fred W

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7/6/2015 - It has been reported that reading all of the comments and discussion in the replies to this thread can be a bit confusing. All of the information required to perform the RDCUA TBS procedure is contained in this first post, or at the procedure linked to immediately below. This post has been updated to reflect the best working procedure for first and second gen FJRs.

(note that the RDCUA TBS cannot be performed on 3rd Gen FJRs)

3/2013 - I have captured and compiled a complete html version of this procedure and am hosting t at my fjr.nerds web space for posterity here: The Really, Definitely, Completely Un-Authorized Throttle Body Sync (TBS)

Re-edited 10/2012
This version of the UnAuthorized TBS procedure is based on a premise; that the ideal throttle synchronization is when the throttle plates are aligned with each other and parallel.

After a large number of uses, this procedure has been found to be very effective. Nobody who has used this procedure has ever said that it made their bike run worse. Most people say that their bike ran smoother (less vibration at ~4k-5k rpm ranges.

You will see some discussion in other posts about alternate ways to adjust the throttle plates. Some folks believe that you need to rev the engine. Some think that you need to load the engine and rev it. None of these other methods have been shown to be any more effective than doing it the way detailed here. And this way is a lot easier to do.






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The Really Definitely Completely UnAuthorized Throttle Body Sync
I decided to start a new thread to document this procedure. Not because it is so much different than any of the other UA TBS procedures, but because there are so many Throttle Body Sync threads. I'm hoping that this procedure becomes the new standard non-standard. The concept for this TBS procedure came from a thread / discussion I had with a short duration forum member from Maine, Alekso last year. The idea was to make a procedure that wasn't so convoluted and difficult to follow and understand as the original Unauthorized sync procedure.

For those just tuning in, what's going on here is that the "official" throttle body sync procedure, the one called out in the Factory Service Manual (FSM) and specified as a "required" procedure at 4k mi. intervals (what?) is simply an adjustment of the air bypass screws at idle speed. These bypass screws have their primary effect on 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 insignificant. What is significant at larger throttle openings would be the relative angles of the throttle plates.

The problem is that the FSM doesn't specify a procedure for properly aligning the throttle plates. They just say that the plates are set at the factory and to leave em the hell alone...
huh.gif
Being gearhead dweebs, we know that to achieve the smoothest possible running engine it is our goal for each of the 4 cylinders to contribute the identical amount of power per stroke. With Electronic Fuel Injection and Electronic Ignitions, the likelihood of balanced fueling a nd perfect ignition timing is much better than in the days of carburetors and points of the past. So our best tuning opportunity is to try to balance the air intakes, which can be best measured by the intake vacuums.

Prior "Unauthorised" TBS procedures suggested that you just open the throttle while observing the vacuum gauges and make the mechanical adjustments to the throttle linkage quickly. Surely that will work, but at what rpm do we need to go before the air from those bypass screws is nullified? And how sadistic is it to continually rev your engine while making these fine adjustments? (hint - they aren't all that quick)

Enter the RDC (Really Definitely Completely) Un-Authorized TBS.

The concept here is pretty simple. To align the throttle plates and eliminate the air contribution from the air by-pass screws, we just close them all the way before starting. Yep... it's just that simple.

So, to prove the concept I documented my most recent RDC UA TBS using a new (to me) Gunson Carb-tune vacuum gauge that I picked up over the winter:


After propping the tank up out of the way, here are the important adjustment points
(note - your under tank could look this uncluttered after installing the WynPro PAIR Block-Off plates and removing all the PAIR crap):

100_1211.jpg


V1 thru V4 are the 4 standard vacuum take-off points for hooking your vacuum gauge of choice to.

1-2, 2-3, and 3-4 are the mechanical linkage adjustment screws to adjust the relative angles of each cylinder's throttle butterfly plate.

Before I began, I documented what I had for vacuum at idle:
IdleB4.jpg


Not bad. Notice that #1 is a bit low and #4 is a bit high. Now, without making any adjustment I then revved the engine to ~3-4k rpm and used my Vista Cruise to hold it long enough to snap a picture:

3krpmB4.jpg


Hello! What's that? Now cyl #1 is high and #4 is low!! This is not good. No, not good at all...
(well really these aren't all that bad, but you get the idea...)


Procedure:

Close down (lightly) all 4 of the Air Bypass screws:

100_1217.jpg


100_1218.jpg




Depending on how open they were before, your engine may not want to idle. You can either crank the idle adjustment (under the right side of the tank) or use your Vista Cruise to hold a reasonable idle, like I did.

Now that the air screws are out of the picture, you can adjust the throttle plate linkage screws (at idle, not while winding the piss out of your poor engine) and balance the vacuums with the throttle plates angles.

Important: Start by balancing cyl 2-3 since 1 and 4 are effected by that adjustment. The only tricky part is if 2-3 needs adjustment you can't get a screwdriver on the adjustment screw. So, take a guess, shut the engine off, and open the throttle enough to get at the screw head. Adjust it one way and then restart the bike to see if you guessed right.

Once 2-3 is good, the 1-2 and 3-4 adjustments can easily be made invivo. If you want to rev the engine to various RPMs to see how much things vary (or don't), knock yourself out (I did). In fact I was a bit nervous of running the engine in the garage for so long, even with water cooling.

When you are completely happy with the balance, I suggest shutting the engine down, and then dialing in ~ 1 turn CCW (open) into each air bypass screw. Restart the engine and adjust your idle to ~1100rpm.
Now recheck your vacuum gauge. Since the throttle plates are now aligned, if there is any mis-balance simply adjust the bypass screws until it is balanced at idle.

When I completed this procedure I had dead nutz balance at idle, and it varied very, very little at any throttle opening. I have not ridden the bike yet after adjusting. It may not amount to a hill of beans, but at least I now know that, unequivocally the throttle has been fully balanced and any vibration that remains is not being caused by an intake mis-balance.

 
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03HiYoSilver

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Fred,

Nice TBS writeup and good work. I did something similar to this and it works very well and creates a balanced baseline.

 

FJRBluesman

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Thank you sir Fred. I've been waiting a long time for your UTBS post. ;)

BTW - -They looked so close anyway, did it really matter??? Let us know how it test rides.

Thanks. :yahoo:

 
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SacramentoMike

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Depressing. Nice, clear, well-illustrated write up. Any idiot should be able to follow it and perform it flawlessly. I got completely confused. :(

Thank God for Roseville Yamaha.

 

road runner

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Fred

Very nice write up and pics.

Maybe it can get pinned in bin of facts or similar, so others can benefit from it. :rolleyes:

This is the exact way I did mine last year, and it works great. Mine were also very close, but I made them right on. They were so close I don't know if it made any difference in how it runs, but at least I know it's perfect.

It's a much more real world sinc, because now it will be equal all the way threw the RPM's instead of just at idle.

And I need to get a hold of Dave for a set of those plates.

Art

 

RenoJohn

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very good......

I like your thinking and I'll be doing that:

+ close off the air bypass on all cylinders

+ adjust the throttle plate linkage screws (per Un-Authorized methodology)

+ Open air bypass screws ~1turn

+ sync cylinders using air bypass screws

Me likes the Un-Authorized TBS

-----

Me's only thoughts/comments:

After opening the air bypass screws (~1turn per your instructions), I'm assuming we should use cylinder #2 #3 as the baseline to sync the others? This is what I've done in the past.

so my question: How confident are you in the ~1turn open? ....and do you suggest using cylinder #2 #3 as the baseline??

thanks for this write-up totally grooovy

un-sync'd in reno ...John

 
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03HiYoSilver

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RJ,

I believe you meant cylinder #3(baseline) to be turned out 1 turn and then do the fine tuning with the other banks, at least this is what I did.

 

RenoJohn

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RJ,
I believe you meant cylinder #3(baseline) to be turned out 1 turn and then do the fine tuning with the other banks, at least this is what I did.
YES!! thanks, #3, #3 ....I was just testin' ya all's.
Thanks Mr. Silver. I corrected my post.

 

C&C

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Should it be known or mentioned that your intake should be scrupulously clean and free from carbon (especially on the back of the throttle plates); don't known, just asking.

And picking 'nits' here, but when you say, "Once 2-3 is good, the 1-2 and 3-4 adjustments can easily be made invitro."; since the engine is back on, shouldn't that read "in vivo".

In any case, excellent write-up.

 

Constant Mesh

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I could be wrong but I don't believe the 3-4 adjustment is affected by the 2-3 adjustment.

The throttle cables connect directly to TB3 so all the action starts at TB3. On the earlier FJR's the idle position of TB3 is controlled by the adjustment knob throttle stop. On the later models the idle rpm is controlled by a separate air valve and the closed position of TB3 is not adjustable.

 

Fred W

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Yes, I meant to say in vivo, you caught me!

Certainly not in a test tube. Duh. :rolleyes: (edited out my fox paws).

As to the arbitrary 1 turn out on (all 4) air screws before doing the final adjustment there are two general goals at that point: Since the vacuum was just balanced (via the throttle plates) we want to open all of the 4 screws the same amount, and we want the amount of additional air from these openings to put the idle speed somewhere in the middle of the idle adjustment screw's range.

In my case, I took note of the average amount I had to screw them in to reach lightly seated. My #1 was originally only open 1/2 turn and my #4 was open ~1 1/2 turns, so I figured I should shoot for the middle of that. It really shouldn't matter what you make that setting, so long as you make them all equal and then adjust from there. You could open all four screws to 1 1/2 turns if you wanted and then balance them all to #3. Since the engine requires the same amount of intake air to run at 1100 rpm, it would just mean that you may end up bumping down your idle speed adjustment screw compared to mine.

Yeah, my starting vacuums were not very far off, even at higher rpms, so it may not result in a big effect on vibration/smoothness. But as RoadRunner mentions above, at least it is all adjusted now. Hopefully for the better. As was pointed out to me via PM, the ideal way to adjust the throttle plates angles would be under load conditions (on a dyno). Unfortunately most of us don't have that luxury. It would be pretty cool to put a bike that just had this adjustment on a dyno to find out how much difference their is under load. Any takers?

And CM, you are correct. The throttle cable actuates the #3 throttle plate directly so the 3-4 adjustment is not effected by the 2-3. The main reason to get the #2-3 balance right first is because that one is the biggest PITA. The screw head points back where you can't get a driver on it, so you have to keep shutting down, adjusting and re-starting the engine to check the adjustment. You could do the 3-4 first if you really wanted and it should stay adjusted as you adjust 2-3.

I don't think your throttle has to be scrupulously clean, you'll just be balancing out any effect that the dirt may make. You probably should have a good idea that your valve clearances are in spec or you'll be trying to balance that out and may not be so successful.

Also, I have a 1st gen which has the adjustable throttle stop for idle adjust. I don't know how a 2nd gen idle adjust works. If it is as you describe then that may have an effect on this procedure? :unsure:

 
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3dogs

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The TB Sync procedure (fifth post down) that I wrote calls for gently accelerating the engine up to 4k (not revving the piss out of the poor engine that was mentioned) to balance the throttle plates. There are several problems with syncing the throttle blades at idle as outlined in this thread.

When you ride down the Interstate at 70mph the throttle plates are not closed but open part way. Getting them in sync at idle doesn't mean that they are synced/balanced at part throttle (the vast majority of engine operation takes place at part throttle). Accelerating the engine to balance the individual cylinder air flow will be a closer simulation to actual riding conditions than operating the engine at idle with minimum air flow. In fact if you sync the cylinders at idle and then rev the engine you'll find that they are not in balance. I've tried this at idle and the "revving the piss out of the engine" produces a better sync or balance.

Also, when holding the throttle open with a Vista Cruise, or by hand, the cylinders will never seem in balance because there is no load on the engine. Ideally the best sync method would be to use a dyno. With the engine loaded and maintaining real road speed the throttle can be synced accurately under real riding conditions--If you don't have a dyno use the acceleration method and you can get close to the same results. Revving the engine to sync fuel delivery is a method that has been used for years (before EFI) on carburetors both on cars and motorcycles and still is practiced today on carbed and EFI fuel systems.

 

mferriter

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The TB Sync procedure (fifth post down) that I wrote calls for gently accelerating the engine up to 4k (not revving the piss out of the poor engine that was mentioned) to balance the throttle plates. There are several problems with syncing the throttle blades at idle as outlined in this thread.
When you ride down the Interstate at 70mph the throttle plates are not closed but open part way. Getting them in sync at idle doesn't mean that they are synced/balanced at part throttle (the vast majority of engine operation takes place at part throttle). Accelerating the engine to balance the individual cylinder air flow will be a closer simulation to actual riding conditions than operating the engine at idle with minimum air flow. In fact if you sync the cylinders at idle and then rev the engine you'll find that they are not in balance. I've tried this at idle and the "revving the piss out of the engine" produces a better sync or balance.

Also, when holding the throttle open with a Vista Cruise, or by hand, the cylinders will never seem in balance because there is no load on the engine. Ideally the best sync method would be to use a dyno. With the engine loaded and maintaining real road speed the throttle can be synced accurately under real riding conditions--If you don't have a dyno use the acceleration method and you can get close to the same results. Revving the engine to sync fuel delivery is a method that has been used for years (before EFI) on carburetors both on cars and motorcycles and still is practiced today on carbed and EFI fuel systems.
It would be more accurate to do the adjustment while riding down the interstate at 70 mph. Definitely need the throttle lock to free up both hands, though.

 

road runner

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I say the best way would be to send the heads, header, intake, tb's, cats, mufflers, all out to get ported, polished and flow checked and corrected, then sync it on a dyno, and maybe it would be perfect all the time. :crazy: Oh yeah don't forget to index the plugs, and timing reluctor wheel, and get the injectors flow checked. :blink:

and don't forget the octane booster.

 
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snikr

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So Fred W, if I bring over my FJR you going to do this TBS for me?? Sounds like it might be the way to go.

Tom

 
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Very nice information....

...however, I see the "before" pictures, but no "after" pictures.

Is this one a 'dem "have faith in me" deals?

signed,

Doubting Thomas in wheaton :D

 

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