View Full Version : carbie adjustments

05-01-2011, 08:50 AM
I have a 115yamaha and reading an online forum they state 5/8 adjustment. Motor is 2008.

I have adjusted the idle screw so the motor will idle at 700rpm instead of 500( motor will splatter and die).

Any advice of 5/8

05-01-2011, 01:09 PM
Idle mixtures are generally a starting point.. several other things to concider.

Is the compression OK
Is there any fuel leaks and are the fuel filters clean
IS the throttle sincronization correct.
I like to drop each cylinder using the mixture screw to ensure each cylinder is functioning.. also it can take up to 15 seconds for a fuel mixture to take effect on the engine...

A good ear helps a lot :)

05-01-2011, 01:21 PM
Yeah, mixture adjustments are a pain in the date for multicarbs and are never what the book say.
As Gary nsays...they're a starting point and many, many other factors need considering beforehand and afterwards.
I use a stethoscope doing the VW and bikes.

Gon Fishun
05-01-2011, 10:53 PM
We used to use vacuum gauges on triple holden carbies, SU carbs etc to get them balanced. I have no idea if they could be used on an outboard. Perhaps Gary could enlighten us.;D