[wilder days]

anybody adjust the air/fuel mixture screws?
what is the ideal settings?

 

[Mike337]

What year? My 2012 is EFI so I let the computer do the adjusting.

 

[miken6mz]

I think all the 650s are fuel-injected and the mixture is controlled by the ECM (engine control module, i.e. computer).

 

[cliffyk]

There are no "air/fuel mixture screws" on the 650 throttle body, there are only two synchronizing screws are used to align (synchronize) the throttle plates.

I did this on a friend's '09 650; it is done by setting the idle to 1200 rpm using the idle stop screw, and then adjusting the synchronizing screws to get the same manifold vacuum in each cylinder. The adjustments are a bit interactive, I.e. the idle speed may change while adjusting the sync screws, if it does return it to 1200 rpm and recheck the vacuum balance.

In the last set the idle to 1200...

 

[wilder days]

well, I thought they where air fuel mixture screws, somi backed them out until I got the highest idle. scoit seemedbto have a bit more power, but I'm afraid that might mess upnthe engine over time. unfortunately I didn't pay attention tonhow many turns out I turned the screws.

 

[wilder days]

cliff,
how would I go about re adjusting the syncro screws?

 

[Buffalo]

There is a procedure but to do it you will need a multi port vacuum gauge. Basically you adjust it so that the vacuum is the same on both cylinders.