7000 rpm 587?

[Brant]

Hey out there! Why do they set the rev limiter on the 587 motors at 6500rpm? Will they self distruct at 7000? I have a 657 mpem, stator and flywheel that would increase the limit on my GTS......Any thoughts??....

 

[Dr Honda]

nope... 7000 won't instantly kill the engine. But, raising the rev limiter won't make it faster... it will only put more wear on the engine.

during normal riding... your engine doesn't get to it's rev-limiter. It only hits it when the pump becomes unloaded.

So... unless you do some other engine mods... it won't do anything for you.

 

[Brant]

OK: so it won't kill it, so why does the MPEM for the 657 say right on it "do not use on 587 engines or immediate engine damage will occur"? The rev limiter seems to me to be the only difference???

 

[Dr Honda]

It's probably MOSTLY for liability reasons. But there is some truth to it. That engine, under normal operations will be at 6100 RPM. (full throttle, with the pump loaded) Now... if you have a 7000 RPM red-line... your engine will instantly jump 900 RPM when the hull comes out of the water, and it will have to decelerate when the pump loads again. This put's a huge stress on the entire drive system. The RPM itself won't hurt the engine... but the shock load will.


With that said... I'm not sure if there is an ignition timing difference between the two engines. I don't think there is, as long as you are using a 3 wire 650 stator... but I've never actually checked. If you are swapping the stator too... the timing shouldn't be an issue.


Now... as a final word... if you are taking a +15 year old engine, and raising the RPM... it won't live long. If you are taking a new/rebuilt engine... it shouldn't be an issue. (Put in the 159 deg rotary valve to take advantage of the higher RPM)

 

[Dr Honda]

After reading back though all of this.... LET ME SUMMARIZE:


1) Swapping the MPEM, flywheel, and stator will do NOTHING to the performance of a 587 engine, by it self. And, can cause drive train damage.

2) IF... you mod the engine, and get an extra 15 ~ 20 HP first... then the higher rev limiter will be benifical, but it will shorten the life over all.

 

[Dr Honda]

OK... I just thought of one more thing.....



Some of the early 587 (yellow) engines, didn't use an MPEM anyway. They had a stand alone CDI, and "Speed Limiter" box. So, depending on what ski you are talking about, it could be a moot point.

 

[Brant]

I don't quite understand why the extra rpm will shorten it's life. The 587 has the same bottom end as a 657 and less power pushing it. A 15+ year old 657 should be in the same danger or more than 587??? Or do the bearings get used to running at a certain rpm and get stressed if you increase it?? Or is it that the 587 will almost always live longer than another higher revving engine regardless of size?

I guess this all began with me thinking that 500 extra rpm means more MPH. Sounds like that might be flawed thinking!

 

[Chester]

OK: so it won't kill it, so why does the MPEM for the 657 say right on it "do not use on 587 engines or immediate engine damage will occur"? The rev limiter seems to me to be the only difference???

It has nothing to do with the rev limiter. The timing is completely different, that's why you must change all 3 components. If you were to change just the flywheel, your timing would be way off.

Chester

 

[Dr Honda]

I guess this all began with me thinking that 500 extra rpm means more MPH. Sounds like that might be flawed thinking!

More RPM does mean more top speed... but, you will never see that RPM, in the water, if you don't make more HP. SO... as above... all you do is allow the engine to rev higher when it becomes unloaded.

And now confirmed by chester... if you put that MPEM on a stock 587 stator, the timing will be wrong.