TBS air bleed screw bottoming out

[feejerkris]

I'm sure this has been covered before but haven't found any info on a late model FJR. I performed my second throttle body adjustment on my 2016ES. First I tried to use a two cylinder harmonizer and adjust one cylinder at a time against the master (#3) as I like how the harmonizer has no bounce in it and seems very accurate, however, I later read that making adjustments in one cylinder slightly affects the others so a perfect sync might be difficult. So I went back in with a Carbtune Pro and started over and found that everything was close but not in perfect balance, so I made the necessary adjustments and cylinders 1-3 were spot on but 4 was just a hair low so I went to turn the screw in and after just a slight turn the screw bottomed out. It seems within spec but is this normal? What happens when I do my next sync and cylinder 4 is low but there's no adjustment left?

I took a short ride today and the bike SEEMED to run smoother(probably a placebo effect), but still buzzy in the right hand. I'm also wondering if the Carbtune could be out of sync? Not worried about it, just curious if there might be someone who's also had this happen and what he/she did to correct it. Bike's running great so I'm not gonna fart with it until it's next service, just want to be prepared.

Thanks for any info!

FK

 

[escapefjrtist]

Gen IIIs such as yours have a air screw identified with white paint that is the master. Was that #3 on your machine? If so, adjust the remaining three cylinders to that screw. IIRC, seems a lot of our US spec bikes have #1 as the white painted master.

Later model FJRs are very stable regarding TBS adjustments. I haven't needed to touch my '15!

Good luck.

--G

 

[RossKean]

I can't comment on the screw bottoming out or the procedure for the TBS for a 2016 but you can check the carb tune a couple of different ways. With the hoses attached to the ports, make not of positions for the columns. Switch the hoses around and see if the same cylinder gives the same readings (on another channel) or if the readings follow the channels. Alternatively, you can hook all four lines up to a common vacuum source. They should all read the same.

 

[Fred W]

The "master" is the one that is/was already bottomed out. It was the one that had the least vacuum when all 4 screws were fully closed. They adjust the other 3 open as much as it took to match that one. The reasoning is that you want the least possible air introduced to get them all in sync, so that the Throttle-by-wire can open the throttle plates however much it needs to achieve the programmed idle speed.

 

[Carlson]

Are you sure the master is #3? On my 2016 the master is #1.

 

[Fred W]

See my post above yours. The master is NOT necessarily any particular number. It is whichever one has the lowest vacuum when they adjust them. Since it has the lowest vacuum, they can leave it fully closed and mark it with a white dot. The other 3 will be somewhat open (by varying amounts) to match the vacuum of the master with the dot.

If for some reason when you are adjusting the sync later on you find that one of the others have lower vacuum when fully closed than the one with the white dot on it, you should make that one the new master and open the other three up to match its vacuum. There have been some people that reported having 2 or more air screws fully closed. As long as their vacuums all match that is fine. The less bypass air that is going through the air screw orifices the better.

 

[feejerkris]

The "master" is the one that is/was already bottomed out. It was the one that had the least vacuum when all 4 screws were fully closed. They adjust the other 3 open as much as it took to match that one. The reasoning is that you want the least possible air introduced to get them all in sync, so that the Throttle-by-wire can open the throttle plates however much it needs to achieve the programmed idle speed.

The master on mine is #3 which has the white paint on it. I don't know if it's fully closed or not as the manual(and others) say not to adjust it. #4 is the one that's fully closed.

Are you sure the master is #3? On my 2016 the master is #1.

Yes, it has the white paint on it. 2016 as well.

See my post above yours. The master is NOT necessarily any particular number. It is whichever one has the lowest vacuum when they adjust them. Since it has the lowest vacuum, they can leave it fully closed and mark it with a white dot. The other 3 will be somewhat open (by varying amounts) to match the vacuum of the master with the dot.
If for some reason when you are adjusting the sync later on you find that one of the others have lower vacuum when fully closed than the one with the white dot on it, you should make that one the new master and open the other three up to match its vacuum. There have been some people that reported having 2 or more air screws fully closed. As long as their vacuums all match that is fine. The less bypass air that is going through the air screw orifices the better.

Sounds like a good idea. On my next sync I may try this if needed.

Thanks everyone for your advice!