Yamha 50 Operating RPM

[newtoon]

What is the normal operating RPM on a 2005 Yamaha 50 when under a load @ WOT? It is on the back of a 20 ft Cruise Pontoon with factory prop.

[norton383]

If it’s a 2 stroke 4500-5500, four stroke 5000-6000. If it’s a 2 stroke can you tell me what the numbers on the right side of the card just below / in front of the throttle linkage is? Should read something like BCP 63D20 R129, also can you tell me if they are all the same or different.

Thanks

[newtoon]

This is a new 2 stroke. Don't have numbers handy right now. But the most I can get , according to the factory installed tachometer is 2100 RPM's at full throttle.

[Ken]

newtoon,
Got back to the dealer - they should provide you with a prop that has less pitch to give you approx 5000 rpm on plane and full throttle.
Good luck,
Ken K

[norton383]

If your only turning 2100 something is severally wrong, either there is WAY to much prop for your boat, something is wrong with the motor itself, or maybe the boat just has to much drag. If you could send those numbers later I would greatly appreciate it.

Good Luck

[norton383]

Newtoon,
If you check the performance Bulletins on the Yamaha site they conducted test on similar boats using a 12 ¼ X 9 prop. With this setup all boats tested were able to obtain over 5000 RPM. The number is on the back of the prop, you might want to pull yours off and see what size it is.

Good Luck

[kingfish]

Newtoon-

Digital or analog tachometer? If analog, be sure your setting on the backside of the tach is correct.

[newtoon]

OK, the TACH is analog and the dealer thinks there is something wrong there. What setting on the back are you referring to? Also the dealer says that a 50 Yamaha on a 20 foot pontoon is only going to go about 18 mph, but willing to try a few props to see if helps.

[Ken]

newtoon,
18 mph for a 20 foot pontoon with a 50 hp sounds about right - get that tack fixed and then try to get your max rpms at approx 5000 with the right prop.
Ken K

[kingfish]

Newtoon-

I'm not as familiar off the cuff with the settings as I wish I was (memory getting shorter), but there is a small set screw on the back of your tach with 4 or 5 settings, each of which are identified with a number. The numbered settings are the same across all the tach manufacturers, so you need to find out from your dealer, or from someone here who is more conversant than I am, what the setting should be for your motor, then observe that your setting is correct.