Vibration post throttle Sync

[Abiram Menon]

@Motogiro and @TownsendsFJR1300 Please Help. I'm dealing with a rather complex issue here. I entrusted my decently reputed garage to change my spark plugs, and they asked me permission to clean the throttle body. They cleaned and damaged the O-rings! Now, I'm dealing with all kinds of idling and vacuum sync issues (V-twin sound beat included). The sync imbalance is causing the infamous resonance at 5k to 7k rpm. They managed to replace the O-rings with some similar size and got back the idling and the vacuum sync on the 5th attempt. But now, i have a snatchy throttle (sudden surge of power in small openings). They mentioned that there's some leak, have corrected up to 90% and cannot do 100% vacuum sync coz of this. Should I specifically order some OEM O-rings if they are available? Also, to my horror, I found out that half of the airbox screws have lost thread. Will this create any other issues? Somehow the remaining three screws are tight enough. I am trying to find the source of minor vibrations further. Is there any other direction towards what all are to be checked for vibrations?

1) There's a noticeable resonance coming from under the seat/subframe
2) Exhaust headers are never checked. Shall I?
3) Rev and touch the cylinder head (Cold); I can feel it's silken smooth. But there's a Givi crash guard which, if I hold, will vibrate our whole body (One mount connected to the engine mount)
4) Spark plug caps?
5) Valve Clearance?
6) Checking all fairing mounts and screws? Torque check?

 

[Motogiro]

My thought is why would they ask permission to clean the throttle bodies. Something else is likely the issue here. First I would look for an error code that might help diagnose the issue.
If they did the plugs, I suggest inspecting the wires from the coils including the plug connectors where the wires enter the boots. I would also pull the plugs and look for a bad gap setting or damaged plug/s.

I'm sure Gary and Scott will add to this.

 

[TownsendsFJR1300]

Which o-rings are in question? On the end of each TB, where the shaft goes thru?


In any event, I would definitly have the proper O-rings installed.. That ALONE would cause issues...

We need to know exactly what they did (if possible).
The TB sync is done at the TB "block" (see below pic).

With 4 TB's, (#'s 1 &2, then #'s 3 & 4) there is an adjustment screw for the shafts (yes 2),
between them. That should not have been messed with. It's the physical "linkage" between the two in-line shafts.

(I had a shop adjust that on my FJR before I had a Carb mate. You could see where the factory paint spot on the adjuster
was obviously turned- I had to adjust that back then re-sync everything)).




Below pic is where that adjuster is located:
.

 

[Abiram Menon]

My thought is, why would they ask permission to clean the throttle bodies? Something else is likely the issue here. First, I would look for an error code that might help diagnose the issue.
If they did the plugs, I suggest inspecting the wires from the coils including the plug connectors where the wires enter the boots. I would also pull the plugs and look for a bad gap setting or damaged plug/s.

I'm sure Gary and Scott will add to this.

They just sent me the pictures and said the TB looked dirty and that they should clean it, and I said yes, please. I will check for the error codes again, as I took pictures when the issue was there last month. I'll also check the plug connectors. For the spark plugs, they installed four new Iridium plugs, as the old ones were worn out. Again, they shared the pictures for me to see.

 

[Abiram Menon]

Which o-rings are in question? On the end of each TB, where the shaft goes thru?


In any event, I would definitly have the proper O-rings installed.. That ALONE would cause issues...

We need to know exactly what they did (if possible).
The TB sync is done at the TB "block" (see below pic).

With 4 TB's, (#'s 1 &2, then #'s 3 & 4) there is an adjustment screw for the shafts (yes 2),
between them. That should not have been messed with. It's the physical "linkage" between the two in-line shafts.

(I had a shop adjust that on my FJR before I had a Carb mate. You could see where the factory paint spot on the adjuster
was obviously turned- I had to adjust that back then re-sync everything)).




Below pic is where that adjuster is located:
.

Part no: 27 (I guess it is a small O-ring? air screw O ring X 4nos, I think) They replaced a bunch of tiny O-rings (which resembles part no: 27), gave me the old ones in my hand, and told me this was the issue. They replaced them with some generic Carburettor jet O-rings of similar size. Will that be the cause of the vacuum leak?

Can you elaborate more on the shaft, which they should not have messed with?

 

[TownsendsFJR1300]

Can you elaborate more on the shaft, which they should not have messed with?

Post # 3 , picture #2...

You have TB 1 & 2 bolted together as well as TB #3 & 4.

To link those together is a spring (to keep tension) and an adjustable screw to sync the two sets.
Your physically linking the two separate shafts and can adjust them (ultimately the butterflies).

If they messed with them and their out of sync you can check with a feeler gauge down the TB's.
Measure between the closed butterflies and the bore itself. They should be spot on or super close.

.

.

 

[Gary in NJ]

All good input above. I would also try to replicate the vibration with the bike on the center stand to see if you have a sympathetic vibration because something unrelated is lose. The shop may have not re-tightened all fasteners or maybe didn't properly route an item (hose, cable, wire harness...). The FSM is very specific as to how items are routed under the fuel tank.

 

[TownsendsFJR1300]

Thinking about this, a newly induced miss-fire would cause new / different vibrations.

Just because the plugs are new doesn't mean their good.

Do you have access to a lazer temp gun? If so, check the temp at the header\tubes
just as they exit the head. They should all be relatively close.

If you don't have one, a little spritz of water, in the same area, should sizzle off about the same,
across the board.
If one cylinder isn't firing, the evaporation of the spritzed water should be noticeably less.


*Me thinks we need to focus on where any work was done and anything else (new parts) associated with it..

.

 

[Gary in NJ]

A dead cylinder wouldn’t be present at a narrow rpm range. It would always be dead and wouldn’t idle well.

 

[Abiram Menon]

I will try all those this weekend as more spare parts are coming. I'll let you know once I know about the issues in real

 

[JM87Sev]

I will try all those this weekend as more spare parts are coming. I'll let you know once I know about the issues in real

Good morning

Have you managed to solve the vibrations/humming at 7000 rpm? I've had them since I bought the bike without touching anything. I've done everything except synchronize the throttle bodies. I'm waiting for the Carbtune Pro 4. Regards.