RPM limiter

[pstephens46]

I have heard that some Yamaha motors will drop cylinders to limit rpm at some max level? Anybody know if this is true?

[fairdeal]

I imagine any motor with "microprocessor" control

you have an F150? then this:

[pstephens46]

Thanks. I have a YDS but only hooked it up once or twice. I did notice the hours at rpm section showed 2 hours above 6200rpm! I have had it for half of the total life in hours and never ran above 5800. The motor would have to come out of the water to get there. To get it with trim the boat would slow down dramatically. Why would someone want that? Puzzling...can't complain, still runs good!

[fairdeal]

In the almost 900 hours I've owned the F225, I've never had it to 5,000 rpms.

Just no need or desire.

I bought a used F225 ECU last year on eBay, this is what it had on it when I got it:



almost half the hours at idle, the other half >5000

111 hours >6000 !

no wonder it was being parted out at 2000 hours....

[boscoe99]

Thanks. I have a YDS but only hooked it up once or twice. I did notice the hours at rpm section showed 2 hours above 6200rpm! I have had it for half of the total life in hours and never ran above 5800. The motor would have to come out of the water to get there. To get it with trim the boat would slow down dramatically. Why would someone want that? Puzzling...can't complain, still runs good!

Ever heard the term "barking the props". It is when the boat, motor and propeller leave the water and the motor over speeds for a second or so until the boat and motor go back down into the water. Motor may be running at wide open throttle, boat at top speed, in good size waves.

Customer then complains to Yamaha about his lower unit failing early, but at least it is under warranty. Or so he thinks. Yamaha knows what is going on but generally will authorize a new lower unit anyway. At least one time.

[boscoe99]

In the almost 900 hours I've owned the F225, I've never had it to 5,000 rpms.

Just no need or desire.

I bought a used F225 ECU last year on eBay, this is what it had on it when I got it:

almost half the hours at idle, the other half >5000

111 hours >6000 !

no wonder it was being parted out at 2000 hours....

How do you know that is propped optimally unless you run the motor at wide open throttle?

How do you know that the motor is outputting its normal power without doing a wide open throttle check?

[pstephens46]

In the almost 900 hours I've owned the F225, I've never had it to 5,000 rpms.

Just no need or desire.

I bought a used F225 ECU last year on eBay, this is what it had on it when I got it:



almost half the hours at idle, the other half >5000

111 hours >6000 !

no wonder it was being parted out at 2000 hours....

Testament to Yamaha that it lasted 2000 hours. Verado? Never....

[fairdeal]

How do you know that is propped optimally unless you run the motor at wide open throttle?

exact boat, motor, prop - I need to re-invent the wheel?

How do you know that the motor is outputting its normal power without doing a wide open throttle check?

from the same document :


when it matches through the peak of the torque /efficiency curve, I don't feel I need to wind it out any further...

[TownsendsFJR1300]

I usually run around 4,000 RPMs, (30MPH), but do run it up to WOT (5,900 RPM's) just to make sure the engine is operating properly.

Usually 2-3 seconds tops as its now at about 46 MPH and the boat gets VERY "skitchy" going that fast....

[pstephens46]

Have to ask. What is the make and model of this boat? We have seen bits and pieces over the few years.....

[boscoe99]

The motor needs to have a propeller that will allow the motor to turn at or near its red line RPM when the throttle is wide open and the engine is trimmed to the most efficient position. With the boat loaded and in summer time conditions. The closer it gets to 6000 RPM the better.

Without doing a wide open throttle check how can anyone ever know?

If the motor can only turn say 5000 RPM at WOT then the motor is being lugged. At all RPM's. It can be perceived as a dog. Which is what many perceive the F225 to be. Mostly because they are over propped.

Now from a health monitoring stand point it is good to know what one's healthy motor will turn when at wide open throttle. Let's say it is 5900 RPM. Year after year it turns this RPM. Now some years later the motor will only turn 5500 RPM. Something is not right.

[fairdeal]

Have to ask. What is the make and model of this boat? We have seen bits and pieces over the few years.....

mine or Scott's?

I have a Sailfish

[url=https://postimg.org/image/w7dk9z7ax/]

[fairdeal]

Now from a health monitoring stand point it is good to know what one's healthy motor will turn when at wide open throttle. Let's say it is 5900 RPM. Year after year it turns this RPM. Now some years later the motor will only turn 5500 RPM. Something is not right.

I'm sure you are right.

I recall some years ago, wanting to take up bicycling again after a long sedentary period,

I visited a cardiologist for a "stress test" to determine if that was OK.

As they were prepping me,

they explained there was a possibility I would die whilst obtaining the result...

[TownsendsFJR1300]

Just a side note(have posted before about it). While doing a WOT run sometime ago, I had a bad hesitation at 5,300, then it'd drop (on a test run).

Eventually I found the issue (Old spark plugs) and after replacement, back to 5,900. Now had I not done a brief WOT run, I wouldn't have known I even had an issue.

I agree, just a brief run WOT won't hurt anything (just don't over rev of course). Blow those injectors out too!!

[boscoe99]

mine or Scott's?

I have a Sailfish

[url=https://postimg.org/image/w7dk9z7ax/]

Damn good looking boat.