Optimal RPM range for Yamaha 30 HP 2 stroke

[Mallards Only]

[QUOTE=Bill Van Steenwyk;146948]

Sorry for the delay. So, it appears that the TT was on the wrong setting as my idle RPM's were running about 2050. Problem now is I'm not sure what setting is the correct one. The TT has settings for SP ARK PER REVOLUTION. If it's a 3-cylinder motor, do I need to have it on 3P1r or 3 sparks per revolution? Or is it based on 2-stroke and therefore 2P1r? If someone knows what the idle RPM's should be, that would help me as well.[/Q


Mallard:

A two stroke motor fires ONCE each RPM (revolution per minute) for each cylinder. Three cylinders, one firing impulse each revolution per cylinder = 3 firing impulses per revolution for this motor.

Hope this helps. When you get it (the TT) adjusted correctly you should read 5000-6000 RPM at WOT depending on prop pitch.

Thanks. Exactly the information I needed. At that setting on the TT, RPM's are 650-700 at idle. Sound about right? Haven't taken it out and run it WOT yet but what's interesting is that WOT on the hose in neutral is only giving me 3500-4000 rpm's. Do these motors have a "governor" that won't allow you to take it to WOT unless in gear?

[FrenchPhil]

Avoid over-idling on the hose.

[Bill Van Steenwyk]

[QUOTE=Mallards Only;146949]

Thanks. Exactly the information I needed. At that setting on the TT, RPM's are 650-700 at idle. Sound about right? Haven't taken it out and run it WOT yet but what's interesting is that WOT on the hose in neutral is only giving me 3500-4000 rpm's. Do these motors have a "governor" that won't allow you to take it to WOT unless in gear?

Mallard:

I am not intimately familiar with your motor to be able to answer the question about idle speed, although is does seem to be about right.

BUT, as French Phil states, you should not rev the motor without a load ( i.e in the water and with the motor pushing the boat) as you might do damage to various components. It sounds as though there may be some sort of interconnect between the CPU on your motor and the gear shift lever so as to prevent it from reving past 3500-4000 RPM's unless it is in gear or a load on it. I would strongly advise you not to try to bypass these features AND put it in the water to check your WOT revs.

Glad to try to help, but you can't cure stupidity if you know what I mean. If the motor won't rev past the RPM you state then there is a reason for it. I realize you want to solve the problem as easily as possible, but the motor was made the way it is to protect it from just what you are trying to do. NO LOAD AND EXCESSIVE RPM'S WILL TEAR THE MOTOR UP!! You have your tach set correctly now, so go to the lake to check it further.

Not calling YOU stupid, just you have gone about as far as you can go with what you have done. Now you need to go to the lake!!


Good Luck!!

[Mallards Only]

Understood. That was my plan. I only took the throttle up briefly to see how high the readings were. I didn't run it there without a load for more than a few seconds. I'll take it out on the water for the next test. Thanks.

[Bill Van Steenwyk]

Understood. That was my plan. I only took the throttle up briefly to see how high the readings were. I didn't run it there without a load for more than a few seconds. I'll take it out on the water for the next test. Thanks.

Mallard:

I seem to remember that the older motors (before EFI and computer controls) had a simple carb linkage that unless the motor was shifted into "forward" would not allow the throttle to be advanced to WOT, or blocked it until the lever was in forward. Perhaps yours has something as simple as this.

Let us know whether this solved the TT problem as there are many posts about this tach on this and other forums. They can be frustrating if not set right.

[Mallards Only]

Will do. Thanks for the help.

[Tiller guy]

[QUOTE=Mallards Only;146949]

Thanks. Exactly the information I needed. At that setting on the TT, RPM's are 650-700 at idle. Sound about right? Haven't taken it out and run it WOT yet but what's interesting is that WOT on the hose in neutral is only giving me 3500-4000 rpm's. Do these motors have a "governor" that won't allow you to take it to WOT unless in gear?

My Yamaha 30 has nothing to prevent over revving in neutral. Nothing has been removed or played with as far as I know. The cdi doesn't have any way to detect gear position either.

[Fastjeff57]

Try wrapping the plug wires next to the one you're using with aluminum foil. That keeps the interference down and improves operation.

Jeff

[Fastjeff57]

Aluminum foil tape works even better.

Jeff

[Mallards Only]

Alright, finally got the boat back on the water to check the RPM's again. Something just doesn't seem right though. With the TT set at 3p1r as Bill suggested, my RPM's range from 400(idle) to 3200(WOT). With the TT set at 2p1r, RPM's are running 600-4800. Even at the 2p1r setting, that seems low and the 3p1r setting is REALLY low. I know it's not overpropped. If anything, the prop on it now is pretty worn and a little chewed on the edges--not enough to create increased drag on the RPM's though. Now what? I'd take it to a Certified Yamaha mech to have them check it but I don't have one within 100 mi.