Merc XR Tecknology

[CranberryRacer]

Can anybody discuss what is the major differences in the Mercury XR series of motors .I am going to purchase a used 150 XR and would like to know more about them. I know they are the " racing version" but can they be used on a regular boat without any perfrmance issues. What should I be looking for. I am going to put it on a Baja 210 sport. I have a jackplate on it now. What type of prop do you think would be right for the Baja. What king of speed should I be looking for. Iam not sure this is the right motor.

Thanks

[pyro]

Which "XR" motor makes a big difference.
150 XR2 2.0L with 2:1 gears
150 XR4 2.4L with 1.87 gears
150 XR6 2.5L with 1.87 gears
200 XRi 2.4L 1.87 EFI
200 XRi 2.5L 1.87 EFI

These motors are no less reliable than any other motor.


The 150 XR2 is completely different from the racing "XR2" motor, which was a Europe/Au export motor.
"XR2" vs. 150 XR2 are kind of like Ford GT vs. Ford Escort GT.
The 150 XR2 was a basic 2.0 150 with some very minor part upgrades with a little bit more RPM capability.

You really don't want to hang a 150 on a 21 foot boat. You'll be disappointed, even without the family aboard. Look for a good used stock 200 at the least. A 3.0L 225 would be ideal.

[CranberryRacer]

Thanks for the info this one is the XR4 and is in good shape. I am in a bit of a pickle. I have a 16 Starcraft ( fiberglass) Carlson racing series. With a New 115 powerhead. runs GPS at 62 . Its realy 2 seater and the wife and daughter also the dog wont go out in it unless its perfectly calm. So I picked up a Baja 210 with a running but worn out 235 Evinrude. This is a big wide skier and they all like the stability. The motor turns out to be low compression on one side, so I thought I would throw the XR4 on it.
Thanks again for info. Maybe Ill run the XR for a season and look for a 200.

Steve M.

[pyro]

Prop it down and let it spin, your ideal ski prop will be able to do 6500 rpm easily. Don't bog it down.

[CranberryRacer]

Ill be carefull with the prop. Ill just keep the rpm up. then look for the 200+
Steve M.

[j_martin]

With a few easy mods, that motor is a real work horse. A little more compression (and 92 octane gas), discard the timing module(s) (limiters) and time it right (23* I think), and it's a bit stronger than 150. :D Might be enough for a family boat. Make sure the LU is in good shape, it's a little smallish.

[pyro]

...or leave it stock and watch it run for a decade or two...

[props4u2]

The xr4's came stock with a small 4 1/4" gearcase with 1.78:1 gear ratio, not a good combination for a heavier boat. A 150 or 200 lower unit will fit in place of the lighter duty 4 1/4" gearcase and is much more durable. This engine also has a long small tuner good for bottom end torque but is only good for 5600 rpm's, install an older style 200 or 150 xr2 tuner, remove modules as stated above, set timming to 23-25%, makes about 175 hp.


Lee

[pyro]

He's talking about putting a tired 150 on a heavy 21 foot boat, and you guys are dead-set on recommending every possible modification in the book, for a motor that realistically only needs to have good bottom end and sub-6000 RPM top end with a 19 or maybe 21p prop. :confused: ...not a 7000 rpm, sick idling, high compression motor with no low end.

Gearcase, good point. If you have the small case, you could probably make a buck swapping to an ordinary case, and it will likely be stronger.

Wheh I made the 6500 reference, I was simply saying that it he was using a "ski prop", it's probably going to be able to turn more than its recommended range.