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Idle adjustment , need help !!!


Vernon

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So I have a 2002 BMW R1150 RTP , I think it is idling too low, and want to adjust it up where it should be. How is this done ? It is idling at 800rpm and should be around 1150 or so, according to BMW specs, I don't want to have to take it to the dealer just to have the idle adjusted, Please help !!!!!

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So I have a 2002 BMW R1150 RTP , I think it is idling too low, and want to adjust it up where it should be. How is this done ? It is idling at 800rpm and should be around 1150 or so, according to BMW specs, I don't want to have to take it to the dealer just to have the idle adjusted, Please help !!!!!

 

 

Vernon, the quick & dirty way is to just back the idle air by-pass screw out about ¼ to ½ turn on each throttle body.. They MUST be kept even as far as total movement is concerned.. You can do that by watching the screw slot angle..

 

You will probably need to remove the plastic Tupperware on the L/H side to expose the TBI unit but there is an access hole in the Tupperware on the R/H side that you can insert a long screwdriver through without removing the plastic Tupperware..

 

 

The above is not the best way just the easiest & quickest..

 

Now on the proper way—

 

More than likely your idle speed is low because the brass air by-pass screws (BBS) & their seats are full of carbon, gum or coking.. The proper way is to remove the brass screws & clean their tips & the seats down in the TBI units with catalytic converter SAFE carburetor cleaner then reinstall & adjust per the service manual so TBI balance is set correctly & evenly.. Those screws should be set using a manometer of some type (either a twin max,, carb stix,, or a homemade U tube manometer so the side to side intake air flow is balanced..

 

Another option is to turn each screw in until LIGHTLY seated while counting the EXACT number of turns & partial turns.. Then back them completely out & clean the seats & screw tips,, then re-install them back to exactly where they were.. If that restores the idle speed then OK,, if the idle speed is still low back each out a little but the same side to side..

 

If you don’t know the history of the bike or past maintenance history it would probably be best to clean the TBI (BBS) screws,, their seats, & clean the throttle bores around the throttle plates then do a complete idle & off idle TBI balance.. Might also be best to do a valve adjustment before the TBI balance as valve adjustment can effect the TBI balance..

 

Check the archives on this site (use the search function) as there is lots posted on TBI balance,, BBS cleaning,, valve adjustment, idle setting,, etc..

 

One last thing—If you have disconnected the battery or had a dead battery you should do a TPS re-learn.. To do that disconnect the battery or pull the #5 Motronic fuse for about 30 seconds.. Then hook the battery up or re-install the #5 fuse,, turn the key on (do not start),, then open & close the throttle completely twice (make sure the choke in NOT on during the re-set procedure).. That should teach the fueling computer where fully open & fully closed throttle is..

 

Twisty

 

 

 

 

 

Throttlebody.jpg

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I have the opposite problem; when the engine has fully warmed to operating temperature, the idle speed is ~1400 rpm, which strikes me as a bit high. Therefore, should I turn the idle air by-pass screw IN about ¼ to ½ turn on each throttle body? Followed by a re-balance, of course.

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