2005 Mercury 150 XR6 \ MAX RPMs @ 4800

Good Morning,

Recently purchased a used 2005 Nitro 288 with a 150 Merc XR6. I have had it on the water 3 times now and the engine appears to run very well - no obvious signs of trouble to the ear - gets right up on plane. The engine does have some difficulty starting after sitting but does not exhibit those signs once warmed up, cranks right up.

Recently tried my buddies 23p prop and found the RPM's couldn't get above 4800. So we put back on my 19p and found the engine couldn't go above 4800 RPM. This doesn't seem right to me.

Is there anything between the throttle and engine that could cap max RPM's @ 4800? This outboard is rated for 5600.

I've seen some talk about a faulty CDM module but haven't found much information on this thing.


Thank you so much!

Re: 2005 Mercury 150 XR6 \ MAX RPMs @ 4800

I was able to get 5400 RPM with only myself in the boat. Also, I had it trimmed high but I managed to get 51 mph with my 19p LASER II prop. Ordered a 17p High Five last week - will post those results after test.

This is a 21 foot boat weighing about 1807 lbs dry. The 150 gets the job done but unless you wind it up with high trim - she likes no more than 4800 RPM. I'm learning - thank you.

Re: 2005 Mercury 150 XR6 \ MAX RPMs @ 4800

The 17 should get you were you need to be to not lug the motor...you need to be on the high side of max rpm and not low side... i.e. should hit 5500 with no problem with one person and lightly loaded...how high or low you have motor on the transom will change your speed...The 5 blade will give you a huge hole shot but you will lose top speed...less blades the faster you will go...

Re: 2005 Mercury 150 XR6 \ MAX RPMs @ 4800

Also chances are going to a five blade is not going to help get you the higher rpm that you are trying to achieve.

Good luck.

Re: 2005 Mercury 150 XR6 \ MAX RPMs @ 4800

Probably in your "set up". Motor height, prop, offset. Dealers tend ta "bury" tha motor pretty deep and pay little attention ta a "good set up". Being an 'lectronic motor there are other possibilities though since pitch changes don't make any difference.................

Re: 2005 Mercury 150 XR6 \ MAX RPMs @ 4800

setho,

I used to own your boats little brother the 04 Nitro 188 Sport. In fact mine was the same color as yours. Mine was powered by a 07 Optimax 150. I ran a 6" Jack Plate with a 21P Tempest Plus set at 4" below the pad. It would run 56-57MPH (5600-5700RPMS) on the GPS any day of the week with 3 people and 30 gallons of fuel and 57-58MPH (5700-5800RPMs) with just me and the wife on it. It also had one heck of a hole shot. The 288 is only 125 pounds heavier than the 188 BTW.

To get the most out of it you need to duplicate my setup but use a 19P Tempest Plus. The 6" Jack Plate is a must so you can get them motor height right and so is the Tempest Plus. You need the bow lift the Tempest will provide. Setup right I don't see why you can't get 54-55 out of your rig.

Re: 2005 Mercury 150 XR6 \ MAX RPMs @ 4800

You have other problems. You should be able to hit the mid 5000 point or higher with even the 23 pitch.


Try disconnecting the idle stabilizer and setting the max timing to 24 degrees. Then take it for a run. If it runs OK set your idle speed with the idle timing adjustment and call it a day. Throw the stabilizer int he garbage or put it on a shelf somewhere.

Re: 2005 Mercury 150 XR6 \ MAX RPMs @ 4800

wired247 said:

You have other problems. You should be able to hit the mid 5000 point or higher with even the 23 pitch.


Try disconnecting the idle stabilizer and setting the max timing to 24 degrees. Then take it for a run. If it runs OK set your idle speed with the idle timing adjustment and call it a day. Throw the stabilizer int he garbage or put it on a shelf somewhere.

Click to expand...

That definitely may help, but no way will a XR6 turn a 23P prop to mid 5000s on that hull. It's just a slow and heavy hull. Although he did say he got it up to 5400RPMs with just him on it.

When I first got my 188 Sport it was running a 21P Laser 2 and the motor was mounted to the transom as low as it would go. It would run 51-52MPH and turn 5100-5200 RPMs (at the low end of WOT range for a Opti). I picked up 200-300RPMs and 2-3MPH by just installing the jack plate and getting the motor height right.

My experience with the Laser 2 on that hull is that it can't carry a load very well. Put some weight on it and you loose bow lift and performance big time. The Tempest on the other hand carries a load like a Mac truck. I could load mine up and only loose 1-2MPH with that prop. The Tempest would also let me trim the motor up as high as it would go without cavitation and that hull needs the trim if it's ever going to get up on the pad.

Re: 2005 Mercury 150 XR6 \ MAX RPMs @ 4800

Boats a little underpowered.. a good 19 pitch should work fine...

Re: 2005 Mercury 150 XR6 \ MAX RPMs @ 4800

Nitro Set-Up's
2005 Nitro 288 Sport
Optimax 225
24P Trophy
5650 WOT
68 mph
No Jack Plate
3.5" below pad
2 passengers, total Gross weight about 3,450 lbs.
Full tank

Re: 2005 Mercury 150 XR6 \ MAX RPMs @ 4800

Guys, I appreciate all the info. The 17p High Five looks very cool installed and performs VERY well when it comes to getting the boat on plane and smooth operation. There is little reverse torque so I had to put the trailer in a bit further to get the boat unloaded compared to the 19p Laser II. Top-end is sacrificed, as we knew, by about 7 mph.

However, I was able to run 5200 - 5300 WOT @ 44mph with very little trim. The engine load sounds a ton better.

@Dan02gt - I will definitely consider replicating your setup on my rig. Thanks little brother!

@Wired247 - my old boat had the idle stabilizer removed. I've ready forums where dudes have killed engines because that thing malfunctioned.


Thanks for everything!!