Throttle body synch

[andmoon]

I always sync at my fave cruising rpm. No scientific backup but I believe it is smoother.

[planet581g]

I did the throttle body adjustment over the weekend for the first time at 6900 miles. It hardly needed adjustment so I suspect I could have gone significantly longer without touching it. Out of curiosity I took the two non-standard screws (cylinders 1 and 3) out of adjustment to see what happens. It makes the bike idle rough. I'm not speaking from years of motorcycle maintenance, but it seems to suggest that if my bike is idling smoothly that the synchronization is probably not too far off.
 
The cap on cylinder 1 is difficult to reach. I used a pair of forceps to remove it and put it back on. At one point I dropped the cap and it was sitting between the starter and engine case. Luckily it has a metal clip around it so I picked it up with a telescoping magnet tool.
 
This maintenance task seems like a hassle to do every 4000 miles. I think that's what the manual suggests? However, I trust myself to do this much more than I do a shop mechanic. A lot of shops are rushed for time so I get nervous about them working on my vehicles.
 

 

 

 
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[2and3cylinders]

I noted one member state that they sync’d without the air box and filter installed. In reviewing the FSM (2015~2016 edition), on page 3-8 under paragraph“2. Remove:”, it omits instructing removal of the “air filter case” (an error?). Yet on page 3-9 under paragraph “5. Install:”, the FSM instructs installing the “air filter case” before the fuel tank and then checking the throttle body synchronization. Finally and after syncing, on page 3-9 under paragraph “4. Install:”, the FSM instructs reinstallation of the “air filter case”.
 
I have installed extension hoses to the carburetor vacuum ports on all my motorcycles (the FJ-09 is my first FI motorcycle) and synced with the air box and filter installed (at both idle speed and again at 3,000 ~ 3,500 RPM) because the air box and filter does effect carb and TB function. Further evidence the TB on the FJ-09 should be checked and definitely synced with the “air filter case” installed is the FSM recommending adjusting the bypass air screws using the “carburetor angle driver” tool, which appears not to be needed with the air filter case removed.
 
Am I correct here, or are the discrepancies in the FSM just confusing me?
 
I also wonder if the TB should be synced at say 3,500 RPM rather than idle.
 

[clint]

I noted one member state that they sync’d without the air box and filter installed. In reviewing the FSM (2015~2016 edition), on page 3-8 under paragraph“2. Remove:”, it omits instructing removal of the “air filter case” (an error?). Yet on page 3-9 under paragraph “5. Install:”, the FSM instructs installing the “air filter case” before the fuel tank and then checking the throttle body synchronization. Finally and after syncing, on page 3-9 under paragraph “4. Install:”, the FSM instructs reinstallation of the “air filter case”.  
I have installed extension hoses to the carburetor vacuum ports on all my motorcycles (the FJ-09 is my first FI motorcycle) and synced with the air box and filter installed (at both idle speed and again at 3,000 ~ 3,500 RPM) because the air box and filter does effect carb and TB function. Further evidence the TB on the FJ-09 should be checked and definitely synced with the “air filter case” installed is the FSM recommending adjusting the bypass air screws using the “carburetor angle driver” tool, which appears not to be needed with the air filter case removed.
 
Am I correct here, or are the discrepancies in the FSM just confusing me?
 
I also wonder if the TB should be synced at say 3,500 RPM rather than idle.

Several of us have checked the TB sync with and without the airbox installed. No difference was seen at all.  
I synced mine at idle and 3500 RPM paying close attention to the variance between the two. 

[2and3cylinders]

No difference at all?  What gauges were used, I have an old conventional mercury-filled 4-tube manometer made by MP, as well as an electronic "TwinMax".  The TwinMax only compares two cylinders at a time, so you have to go back and forth between the "standard" TB and the other two, which is a bit of a pain but not difficult.  Possibly the Twinmax can discern more of a difference, or maybe not. 
What was the variance you observed at idle and 3,500 RPM?
 
Also, was I correct about the apparent discrepancies in the FSM?
 
And lastly, am I also surmising correctly that without the airbox installed a 90 degree bypass screw tool is not required?  I have the old MP version of this tool but I have a D-head screw bit for my 1998 VTR1000F epoxied over the straight-blade screw bit and would prefer not to have to remove it. 

Several of us have checked the TB sync with and without the airbox installed. No difference was seen at all.  
I synced mine at idle and 3500 RPM paying close attention to the variance between the two.