synchronize yamaha carbs

[ssoileau]

I have a 1998 90 hp 2 stroke yamaha ( not oil enjected) Model C90TLRW. How do I synchronize the carbs.

 

[99yam40]

Re: synchronize yamaha carbs

Pick up a Yamaha service manual for that motor and follow the steps or wait for someone with that manual to try and type all steps for doing it

 

[drolds72]

Re: synchronize yamaha carbs

Get yourself a manometer/carb sticks. Basically what they do, is measure the vacuum at idle for each carb. Then you adjust the carbs so that they all match. I am not familar with the 2 strokes, but on the 4 stroke, each carb has a 6mm plug that gets removed, and an adapter screwed in. Then you attach each tube to each adapter. Start engine, and adjust. If you are using a mercury type, and the carbs may be way off, you might want to pinch off each line before you start it so the mercury does not get sucked into engine. Its not that hard to do if you have the proper tools.

 

[99yam40]

Re: synchronize yamaha carbs

There are no vacuum ports to hook up to on 2 strokes

 

[rodbolt]

Re: synchronize yamaha carbs

unclip the throttle cam and move it away from the roller,back off the idle speed stop screw about 3 turns.
loosen the carb sync screws,make sure all shutters are closed and tighten the sync screws,move the idle stop screw back to its previous llocation,reconnect the throttle cam.
test engine idle speed,adjust cam to roller so the cam contacts the roller when the engine timing is about 8*ATDC but the roller cannot touch the cam at dead idle.