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Throttle body sync r1100rt newbie question


Uncle Mike

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Well I took the 99 R1100RT out to test the brakes and get the engine up to running temp for the throttle sync. The bike would not hold idle and died coming to stops. Once warmed up you can see the idle is way low. The throttle bodies seem pretty even on the carbtune at idle but when I give it some gas you can see the left throttle body goes way down and the right doe not hardly move at all.  Is this a mechanical problem with the cables or internal to the throttle body? 

 

Just wondering if someone has seen this before and can make some suggestions. 

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25 minutes ago, Uncle Mike said:

Well I took the 99 R1100RT out to test the brakes and get the engine up to running temp for the throttle sync. The bike would not hold idle and died coming to stops. Once warmed up you can see the idle is way low. The throttle bodies seem pretty even on the carbtune at idle but when I give it some gas you can see the left throttle body goes way down and the right doe not hardly move at all.  Is this a mechanical problem with the cables or internal to the throttle body? 

 

Just wondering if someone has seen this before and can make some suggestions. 

 

 

 

Evening  Uncle Mike

 

Might be 2 or even 3 unrelated issues, the low idle could be anything from engine mechanical to junked up BBS air passages, or even someone has the adjustments all messed up.  

 

On the above idle throttle balance being off, that more points to a Throttle cable adjustment issue.

 

You just need to work your way through it & make sure all the adjustments are correct.    

 

Start by removing then cleaning the BBS screws then cleaning the air passages under the BBS screws. If that doesn't get your curb idle higher then back each BBS screw out 1/4 turn then re-check the idle RPM & balance. If still low then try another 1/4 turn out. (either count the BBS screw turns to lightly seated before removal or just reinstall both side BBS screws at 1-1/2 turns out from lightly seated), then adjust from there. 

 

On the above-idle cross side balance being off, your gauge shows the L/H  throttle valve opening before the R/H side so try tightening the R/H side throttle cable a little  (back the adjust out slightly) then recheck the balance.  

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Thank you! Took both BBS screws out and they were black with carbon. Hard to see how black in the winter sun going down. Cleaned them off with some throttle body cleaner and sprayed a bit in the holes. Reinstalled and 1 1/2 turns out from seated and I had idle! Most productive 5 minutes I ever had working on a bike or scooter! At least I have a starting point now. 

 

 

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  • 1 month later...

Mike,

 

It's not only the BBS itself but the small passages to and from it that need to be cleaned also.  A little bit of that black stuff in these small passages makes a BIG difference .  These are actually small air passages that bypass the valve plate in the closed position, with the BBS just adjusting the amount of air that can bypass so you can adjust the balance at idle.  Those passages need to be CLEAN, and it takes about a full can of TB cleaner for each TB.  

 

I had to remove both TB's, then remove each BBS and clean it.  Used the small red tube to squirt cleaner into the BBS hole, let it sit for a few minutes, and repeated several times.

 

You can see where the cleaner spray comes out inside the throat of each TB.  Should be two holes, an inlet and outlet.  Alternate putting your finger over each hole to give the full force of the spray to the other side.  When these are CLEAN it makes a HUGE difference in the idle of the engine.  

 

https://photos.app.goo.gl/Id4It7fgBCLEZyzE2

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