[andrez]

Hi,
I trully hope sombody can help as down here the only advice people have got is bring it in ....and your cedit card
first off rev counter from where does it connect
seconed my motor starts and runs well till top end however at 3/4 throttle it seems as if it goes to two cylinders intermitently if i play with the throttle full and back to 3/4 it surges foward only to pull back it does seem not to be revving to a full throttle as i say it pulls well i get her to plain well but feel the engine is not getting 100%.
my boat is4.5 rubber duck with a center consol

[BruceAML]

It would help if you post the year and model number of your motor.

[andrez]

Hi again,
thanks for the reply.....
my motor serial no is y30dm/658/s/003866
I am not sure what year but believe it is a 1999 model

[BruceAML]

What country are you in? The North American models are different from the "world" models.

[andrez]

I am from South Africa.......

[Ray Neudecker]

An engine which surges on the top end normally has a fuel restriction.
Many of the three cylinder models in the states required a conversion kit for the tach to operate.

[BruceAML]

Are you using an external portable gas tank? If so, what kind of fuel line assembly? The factory Yamaha line is far superior to any other fuel lines.

[andrez]

Guy's thanks for the reply's
i think my pipes do need replacing!

[rodbolt]

if its electric start then tap into the green wire from the stator to the regulator/rectifier. if its manual start most still had the wires but not the regulator/rectifier. without the rectifier the factory tach wont work.
your describing a fuel issue, carefully check the fuel lines,filters,tank connections,tank venting and carb fuel bowls for debris.

[andrez]

guy's can one over-rev a engine and or can you hold a engine at full throttle for a period of time

[rodbolt]

I dont know if your model has an RPM limiter built into the CDI. the US models usually did not on the 2 strokes.
normally as long as the cooling system is top notch and the fuel system has no restrictions and the correct amount of oil is added,or the precision blend is properly adjusted,that motor can spin 5000 longer than you can sit on the seat.
if any of the subsystems degrade then all bets are off. kinda like a formula one race car running on 2 year old tires with year old gas and last seasons spark plugs, its just not gonna work.