Yamaha 70hp stops dead at 5500

[Jakalwarrior]

This is a 98 motor. <br />Done this since it was new. Gets to 5500 real quick then stops dead. I can see the only dif between the 60 horse and the 70 is that the 70 does 500 more rpms but mine dosent. What gives? Is there any kind of rev limiter removal kit available?

 

[rodbolt]

Re: Yamaha 70hp stops dead at 5500

try a run with test wheel YB-1620. if it will turn 5250-5450 the motor is capeable of making the correct power. use a known good shop tach not the hull tach.

 

[Jakalwarrior]

Re: Yamaha 70hp stops dead at 5500

Have no idea what that is

 

[rodbolt]

Re: Yamaha 70hp stops dead at 5500

then toss parts at it. ya dont even know if you have a problem yet you wanna spend money just not on what needs to be spent. most any dealer should have the correct test wheel and inductive tach. may cost an hours labor or so. 5500 is the middle of the reccomended RPM range. the propeller will act as a govenor if its set up correctly.

 

[rodbolt]

Re: Yamaha 70hp stops dead at 5500

maybe I misunderstood your reply. a test wheel is a speacial "propeller" that is designed to place a specific load on a specific motor and turn a specific RPM. very handy in testing,tuning and troubleshooting as well as isolating motor problems from prop and hull problems.

 

[Jakalwarrior]

Re: Yamaha 70hp stops dead at 5500

Ahh so it's a specialty load testing tool kinda like a dyno except with a specific application. Mostly I was just worried the motor had some sort of electronic rev limiter at 5500 since it gets there quick like it has more in it then stops at exactly 5500. Unlike my old boat with a mercury 200hp that would slowly creep up to its absolute limit (note, bought it used with the rev limiter already removed). I guess if the onboard tach is off it could really be hitting the limit and 5500 is just what the tach is showing.

 

[ivar]

Re: Yamaha 70hp stops dead at 5500

Could be that your tach is off. On many 2-strokes, when past the power peak, the power drops off rather quickly.