Hello I’m brand new to the forum. I’m the second owner of a 2015 FJ-09 and unsure of the maintenance history. Bike has 13,000 miles on it. Made myself a sync tool using clear tuning and tranny fluid. Synchronized the throttle bodies last night and all 3 air bypass screws were turned all the way in as far as they would go. The white baseline adjustment screw is on throttle body #3. #3 vacuum was much stronger then #1 and #2. The fluid was WAY higher up the tube on #3 compared to #1 and #2. Turning the #1 and #2 adjustment screws out made it way worse. I marked exactly where the #3 baseline screw was set and went ahead and turned it out about 1/4 turn and then I was able to get all 3 throttle bodies synchronized while leaving #1 and #2 screws turned all the way in. So yeah I turned the forbidden white screw out almost 1/4 turn. Today I will put the bike all back together and go for a ride and see how it goes. So now what? What’s going to happen now that I turned the forbidden white screw? Why does the manual say not to touch the white screw? Can I harm my engine since I’ve adjusted the forbidden white screw out a little bit? I found it crazy that all 3 screws were turned all the way in. Also I know I should have checked my valve clearances prior to doing the TB sync but I didn’t. I don’t know how and don’t have the time right now because I’m going on a long road trip with the bike in a few days and didn’t want to get into learning and doing the valve check with the minimal spare time I have. So my question is this. Why shouldn’t you touch the white screw and what can happen now that I’ve adjusted it? The bike seams to idle better now then it did before since I’ve adjusted the forbidden white screw and got the throttle bodies in sync. Please any advice is appreciated. Thanks.
All throttle body sync screws seated / bottomed out
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Oh, and don't waste your time checking the valves at 13K but don't let them go until the recommended 26K.
Best time seems to be about 19 or 20K.
Now, with all this new information why were you doing the TB check and concerned about the valves?
Is your bike not running well?
And in closing, welcome to the forum.
Best time seems to be about 19 or 20K.
Now, with all this new information why were you doing the TB check and concerned about the valves?
Is your bike not running well?
And in closing, welcome to the forum.
Thank you. I wanted to do the throttle body sync because Im not sure if it had ever been done at all and it’s a frequent part of the maintenance schedule. It also had a slightly rough idle and didn’t start instantly like it should a couple times recently. The overhaul manual also mentions checking valve clearance prior to doing the throttle body sync so that had me concerned.
Got the bike all back together and went for a rip. There is a noticeable difference. The bike idles smoother, vibrates less, and the power delivery at initial throttle input isn’t jerky anymore, it’s much smoother. I also adjusted the throttle cables and took out most of the slack while I had the gas tank off which is nice. The recommended slack was way too much in my opinion and I didn’t like the feel. The bike starts up instantly, runs smoother and better then it ever has since I got it at 4600 miles. I’m sure it’s been way out of sync the entire time I’ve had it. I should have done this adjustment a long time ago.
Well I adjusted the forbidden white baseline air bypass screw and it’s running better then ever. Still what the hell is
With that screw and why does the manual say not to touch it? In my situation I had to turn it out in order to sync the throttle bodies, nothing else worked. And in my case all 3 air bypass screws were turned all the way in which very weird. Maybe the tech at the factory was hung over and baked when he test ran the engine and “tuned” it. Maybe it’s been improperly synched by the original owner. Who knows but it’s running good now and I hope moving that white baseline screw doesn’t mess anything up.
Got the bike all back together and went for a rip. There is a noticeable difference. The bike idles smoother, vibrates less, and the power delivery at initial throttle input isn’t jerky anymore, it’s much smoother. I also adjusted the throttle cables and took out most of the slack while I had the gas tank off which is nice. The recommended slack was way too much in my opinion and I didn’t like the feel. The bike starts up instantly, runs smoother and better then it ever has since I got it at 4600 miles. I’m sure it’s been way out of sync the entire time I’ve had it. I should have done this adjustment a long time ago.
Well I adjusted the forbidden white baseline air bypass screw and it’s running better then ever. Still what the hell is
With that screw and why does the manual say not to touch it? In my situation I had to turn it out in order to sync the throttle bodies, nothing else worked. And in my case all 3 air bypass screws were turned all the way in which very weird. Maybe the tech at the factory was hung over and baked when he test ran the engine and “tuned” it. Maybe it’s been improperly synched by the original owner. Who knows but it’s running good now and I hope moving that white baseline screw doesn’t mess anything up.
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2,841 Posts
Stop worrying about the white painted screw...You have done no harm to the bike or throttle bodies ! I just did mine at 26,000 miles after a valve job and mine would not balance out at all until I closed the dreaded white screw a 1/4 turn then everything could be lined up and she runs great ! Never put another thought about the forbidden screw..... Your done and she runs great and all is working so just forget about it and stop over thinking it ! I do the same thing at times over thinking but learned to let it go !!
That’s good to know. Sounds like the exact situation I was in with all 3 screws turned all the way in. Well I’m going to stop worrying about it. It’s nice to know others have had to adjust the forbidden screw as well lol. Thanks guys!
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