87 Yamaha 90 hp Float adjustment

I rebuilt all 3 carbs with a serria rebiuld kit and the motor idles fine but once under a load the motor has trouble accelerating and also will die our when you come off the throttle. I notice if I trim all the way down the motor runs real rough but if I trim it half way it will idle and run nice and smooth.

I have heard the floats need to be adjusted. Could someone tell what kind of a tool to use( feeler guage?) and what is the proper adjustment? And I guess how to also.

I dont quite understand the princple of adjusting the float?

Re: 87 Yamaha 90 hp Float adjustment

i use a dial caliper to set my float heights

Re: 87 Yamaha 90 hp Float adjustment

brewmister,

My book says a 14mm +-1mm. Dial calipers are great but for the problems you are having I would think they would be way out.

To check the level, take out the carbs and take off the float chamer lid. Turn it over so the float closes the needle and seat valve. Roughly speaking they should all look the same and be flat. Check the height from the top of the float to the side of the lid. A metal rule with zero right on the end works ok for a +-1mm measurement.

If the float is out you need to bend the tab hitting the needle. Take it out and do it with needle pliers so you don't damage the needle. If you adjust it and it doesn't look flat you are probably taking the incorrect measurement.

Re: 87 Yamaha 90 hp Float adjustment

Thanks so much for the response! I am giong to give that a try along with a diagram I found posted on this great site.

I will let you know how I make out!