bypass screw adjustment

[bigbandit]

Just had a question about adjustment of the throttle body brass screws.My bike runs better,more low end power with the screws out further.My screws were out about 1 turn each,i increased them to 1.5 turns and did the synch.The bike runs better,even shifts better with them out further.I may have lost a little fuel economy with them out further, maybe a mile per gallon.Reading one of the syncronization step by steps,it says to have the screws out as little as possible to achieve syncronization.Should i turn them back in or leave them out?Thanks for all replys. John

[Ken H.]

Reading one of the syncronization step by steps,it says to have the screws out as little as possible to achieve syncronization.

Not sure where you saw that as most all procedures, including the BMW one, say to start with them 1 to 1.5 turns out each. The caution is to have the difference between them as little as possible.

[bigbandit]

Hi Ken, it's in the oilhead maintenance manual,page 57.Written by Stephen Karlan.Thanks John

[T__]

Just had a question about adjustment of the throttle body brass screws.My bike runs better,more low end power with the screws out further.My screws were out about 1 turn each,i increased them to 1.5 turns and did the synch.The bike runs better,even shifts better with them out further.I may have lost a little fuel economy with them out further, maybe a mile per gallon.Reading one of the syncronization step by steps,it says to have the screws out as little as possible to achieve syncronization.Should i turn them back in or leave them out?Thanks for all replys. John

 

John, what year, model, & country bike are you working with?. That makes a difference on how the air by-pass screws effect the operation..

 

Twisty

[Tominator]

The screws (Air Bypass) have little bearing after idle....cable sync is the key

 

Tomas

[Ken H.]

The screws (Air Bypass) have little bearing after idle....cable sync is the key

 

Tomas

Sorry, but I beg to differ a bit. While they are primarily an idle adjustment, the definitely do effect sync at all RPMs.

 

Try it some time. With a sensitive sync measuring tool connected, hold a steady above idle RPM, say 3K or something, then twist on one of the LBS. You'll be surprised how much it affects the balance.

[bigbandit]

Hi Twisty, my bike is a 98rt.I thought i lost fuel mileage after turning out the by pass screws,but i think i gained mileage.My digital bars are dropping off quickly,but distance to low fuel light has increased.I think i bumped a harness when i had the fairings off.My last tank figured out over 53 mpg,combination city and hwy.The screws were out 1 turn,i increased them to 1.5 turns,then synched the throttle bodies.Lot more low end power and shifts better also. Thanks for the help

John