Yamaha F90 4 stroke

[Kanadakid]

My Yamaha F 90 runs at 4900 RPMs WOT. What are others getting (RPMs) from this engine ?<br /><br /><br />Kid

 

[WillyBWright]

Re: Yamaha F90 4 stroke

You should be twisting closer to 6000. You might have a prop with too much pitch, there might be something wrong with the motor, or your tach setting could be incorrect. Most marine tachs can be used on many different motors. There is usually a rotary switch to change to the appropriate setting. In some of the Yamaha digital gauges there are tiny switches inside the tach that need to be set correctly.

 

[bossee]

Re: Yamaha F90 4 stroke

Hi,<br />If You have a look at the Yamaha F90 Owners Manual You can se this (Maintenance, Specifications):<br /><br />Performance:<br />Full throttle operating range:<br />5000–6000 r/min<br />Maximum output:<br />F90TR 66.2 kW@5500 r/min (90 HP@5500<br />r/min)<br />Idling speed (in neutral):<br />700 ±50 r/min<br /><br />So You chould aim at approx 5500 rpm but up to 6000 rpm should be OK also at full throttle, assuming your tachometer is showing correct.

 

[mike paulson]

Re: Yamaha F90 4 stroke

When I was using a 13"x19" prop I was getting 6000 WOT. I then switched to 13"x21" and was only able to get 4900-5000 WOT. I then raised the motor 2" higher on the motor pod and now get 5300-5400 WOT with the 21" pitched prop.<br /><br />cheers...

 

[Kanadakid]

Re: Yamaha F90 4 stroke

Thanks for the replys. This is a jet outboard so it is a 90 /65. The dealer says he is going to order a new Impeller that will get me another <br />400 rpm. But this still seems far less than normal spec.<br /><br />The engine sounds and run fine. Starts in clod weather with a flick of the key. <br /><br />I have also been using mobile one oil usively in the engine. Used the normal oil for breaking and now on Mobile 1.<br /><br />Not sure why the engine is so far out of spec.<br /><br /><br />Kid