Thottle Bodies ....The Lentini Way

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Coxwain

Race Dog
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Nov 7, 2009
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BMW R1150GS
I've just spent a very pleasant morning setting up my Old Girls throttle bodies and she is now purrrring like a contented cat.
Some tips that might help you guys, are as follows. This is going to get a little technical, but believe me, if you do it right, the difference is astounding.

Step 1.
Remove both throttle bodies. (or you can do them one at a time.)  Check that the butterfly disc is centered in the throttle body bore. ("WHAT"  I hear you all shout....) Yes ..this is something I have just found out. If you have rebuilt your throttle bodies with new shafts, the butterfly's may not be centered. "How so" you ask. Well.....the butterfly's "float" on the spindle until the screws are tightened, if the spindle shaft is not in the fully closed position when you tighten the screws and nuts, the disc will be out of center and on the left throttle body this affects the TPS reading. Both of mine where out.
How to check ...take your cell phone and turn on the torch , find a dark place and place the TB , end up over the light. The light around the edges of the disc should be equal. If you have screwed out the dreaded throttle stops....and you should, there should be very little light coming through. This only applies to rebuilt TB, if it hasn't  been done ...don't worry .

Step 2   " Now we get down and dirty."
We are going to set up the left side TB first. 
Refit the TB to the motor (Duh...) and make sure there is 2mm free play on the cable
Loosen off the throttle stop screw fully.  (STOP SCREAMING ....its not that big an issue)  the butterfly is now in a fully closed position.
Connect your decent DVM  (Digital Volt Meter) to the TPS as follows.... Positive (Red Cable) to Pin 1... which is the right hand pin on the plug, negative to pin 4 ....left pin.
Loosen the two torque screws on the TPS....  wipe the sweat out of your eyes and take a deep swig on that beer. I know you're skeert , but don't worry, nothing is broken yet. 
Turn on the ignition ... stand back....Is there smoke ?? ...so far so good.
Gently rotate the TPS ...and I mean gently ....until you get a reading of 250mv on the DVM.  Easy does it ...its as sensitive as your lady at that time of the month. Once you have 250mv dialed in.... LOCK THAT SUCKER DOWN. Be careful to maintain the 250mv reading as this is the base reading for the Motronic to determine the angle of the butterfly.  See... I told you it was going to get technical.
OK ...you can grab another beer now , you deserve it.
Now.... its back to that very scary throttle stop screw.  With your DVM still connected .....you didn't disconnect it ....did you ????  Gently screw in the throttle stop screw until you get a reading of between
360mv and 400mv. At sea level a reading of around 380mv is good, at higher altitudes 360mv seems to be about right. When you have it , tighten up the lock nut on the screw ....stand back and congratulate yourself for going to the place where BMW said "No man should ever go"
Don't forget to pull fuse No 5 in the fuse box to reset the Motronic. Leave it out for a few minutes while you reflect on your amazing accomplishment in outsmarting the white coats at BMW.
Replace the fuse and turn on the ignition. Twist the pigs ear a few times to dial in your new settings. 
Check that the BBS is turned out two full turns from closed .....then step away from the left throttle body ....you are done with it.

Step 3    Its all plain sailing from here .....
First things first .....send the wife to replenish the beer supply.
While shes gone , Fit the right hand side TB. Once again make sure there is 2mm play on the throttle cable and the BBS is two full turns out.  Oh....did I mention ....BBS = Big Brass Screw.
OK ....here we hit a fork .....If you didn't unscrew the throttle stop screw (Skeertdy cat) and it still has the blue paint intact .....leave it as is.  If you unscrewed it .....I salute you sir, you are a brave man. Turn it in, until it just touches the stop plate. Don,t lock it just yet.
Now its time to haul out your trusty manometer.  No ...this is not an instrument to measure the length of your dick..... we are going to balance throttle bodies.  If you don't know how and where to connect it ....please close this page... NOW.

OK ...you're still here, so I'm guessing you are all hooked up.    FIRE UP THAT HOG..... shes going to be a bit lumpy at first, cause you haven't set the right hand TB. She should be idling at about 1100 RPM .....if not.... adjust the BBS till you get as close as possible to 1100 RPM.  Check your manometer and adjust to get a good balance. You will also hear when it is right. 
Now, crank up the revs to between 1500 and 2000 rpm (I hope you are on good terms with your neighbour's) and check the manometer. To adjust for balance, use the throttle stop screw ...ONLY ON THE RIGHT HAND SIDE !!!!!!  If you were a whoosy and left the stop screw alone ....use the adjustment on the throttle cable ....it all boils down to the same thing at the end of the day.

The above procedure is based on the Rob Lentini document ....except.....Rob based his ZERO on 010mv which is apparently incorrect. The correct value as calculated by a gentleman on ADV Riders is ZERO = 250mv 

Gentlemen ...I hope this helps. My Old Girl is running like a sewing machine after using this method. If anyone needs any help ....just shout.

I have attached a very comprehensive document and the Lentini procedure is in there. Just remember that the base setting is 250mv and not 010mv as stated in the document. 
 

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  • Oilhead_Maintenance_Manual_R850_R1100_R1150_R1200.pdf
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