so I only can turn 5000rpm...

[stlcheckmate]

I have a 1987 150 xr4 with a 24 pitch 3 blade laser 2 prop on a 20 foot enchanter..and its only turning 5000 rpm and only doing 50mph..shouldnt it be turning around 6200? The tach only goes to 6000rpm anyway so I would need to upgrde tachs..

 

[jallen355]

I ran a 21P Laser II last weekend on my 18' Exciter w/a 89 150 and tunred 5900 @60 mph. I am not a Laser II fan.

I also ran a 23P Stiletto the had been reptiched to a 22P and was turning it 5300rpm @ 60 mph, also.

I'm currently chasing the "right" prop for my boat too. Be sure and post back with any you may get a chane to try. I'm thinking we may both be looking for the same prop.

Does the XR4 have the 2:1 gear case, too?

 

[Blizz]

That's alot of boat for a 150 even if it's a xr4 try raising the motor up a bit to see if you can get some more rpm's out of her. You should be at a min of 5800 WOT.

 

[topher312]

i thought that at WOT you wanted to be anywhere from 5000 to 5500 rpm's. maybe i am mistaken

 

[Boston Predictor]

Blizz is right. Im assuming your motor has no JP and bolted flat on the transom. One way to gain more rpms with any prop is raise that sucker up. Your best bet is a hydraulic jackplate with this motor since a 150 is pretty small for that heavy hull youll definitely need it (or a bigger motor)... Since Ive owned a Hydraulic jp Im never going back to a manual again.

 

[fiftyp]

Up is definitly the way to go. I spun a Laser II @ 5800, bought a jackplate, and came up a couple inches now same motor/prop combo will spin 6200 easy.

 

[Boston Predictor]

Just for refrence, I had a rebuilt 150 w/ a jackplate on a 17' Sportfire and spun a 28'' chopper no problem. When I burried the prop the RPM's went down signifigantly. (spelling???)

 

[Combat Rock]

those numbers sound about right for that combo

 

[Chris]

You guys realize of course that a XR4 is not rated from the factory to spin at 6200 RPM.

I would definitely double check your particular model, but I believe the factory max range is something along the lines of 5400-5800 RPM.

If you're not spinning that and everything else is in order, you normally would go down a notch or two in pitch size.

 

[Blizz]

Yes i realize this but you can spin pretty much any V-6 Merc into the low sixes all day with no problems.

 

[2benchanted]

prop

I have 78 enchanter with a 76 200 evinrude 2 3/4 inch under the pad 12 inch set back and spin a 24 pitch 4 blade with cupping to 4900 and get 57 mph with full load and two on board. Try a 21 pitch tempest and you will be very happy.

 

[JW]

You can spin the standard fishin' Mercs to 6200 rpms, but you're kinda wasting top speed by doing that. The motor is ported to make max power at 5400-5800 rpms, so for best top speed you prop the boat/motor combo so that the engine runs there when WOT.

The ONLY reason to run a fishin' Merc to 6200 is if you need to spin up a small pitch prop for drag racing/hole shot. Still losing your best top end numbers that way though......................