mercury xr4 150

[rwchop]

i have a ranger 360v and it only does about 45 mph the boat doesnt get on plain very fast does any body now what the best prop is to run on mercury xr4 150 i think the motor is 1987

 

[douglas1978]

Re: mercury xr4 150

what prop are you running whats your rpm's at wot and is that gps or speedo reading?

 

[rwchop]

Re: mercury xr4 150

it is gps speed and i dont now rpms and what prop is on it the prop has no numbers on it like there should be just wondering if anybody had good ideas

 

[douglas1978]

Re: mercury xr4 150

rpm's at wot is a good way of making an informed decesion on buying a new prop to see if you need to go up or down in pitch. the numbers should be stamp some where between the blades unless you had some one rebuild it. rpm gauge can be bought for 20 bucks

 

[rwchop]

Re: mercury xr4 150

by chance do you no what prop should be on there or no

 

[Faztbullet]

Re: mercury xr4 150

You cannot set-up a boat & engine with speed data, you need a tach to get engine in its rpm/torque range. Also have you checked to see if engine is running on all cylinders? Is throttle/carbs opening all the way? Does it still have the original small lower unit?

 

[rwchop]

Re: mercury xr4 150

I am at 5000 rpm it is running on all cly and crabs are fine

 

[j_martin]

Re: mercury xr4 150

I am at 5000 rpm it is running on all cly and crabs are fine

Now, with a few other pieces of info, we can help.
1. Take the prop off and read the numbers on the back of it to us.
2. Do you have a jack plate, and how much if you do?
3. What is the height of the prop shaft centerline compared to the bottom of the pad?

With that we could discern if you are running OK and need setup help or a different prop. I'll tell you from the info so far, the engine is sick, or the setup is way wrong, or the boat is wet.

I'm glad the crabs are fine. Do you use butter on them?

That engine would like to be shed of it's "advance" module and set up for about 5900 - 6000 rpm. Should run mid 50's or better.

hope it helps
John

 

[SparkieBoat]

Re: mercury xr4 150

ditto to Martin..he is right on the money. do not forget to change the timing to 25 degrees at WOT after float testing the idle "advance"module.

 

[j_martin]

Re: mercury xr4 150

ditto to Martin..he is right on the money. do not forget to change the timing to 25 degrees at WOT after float testing the idle "advance"module.

Due to possible variations cylinder to cylinder, and today's relatively crappy fuel, I'd set it at 23?, which is the design max at 5000 - 5500 rpm. 25? tends to be a bit rattly at mid throttle, which is full advance, half carb opening. I've done a flip switch test to advance from 23? to 25? at WOT and back on the fly. There is a slight exhaust note change, but unmeasurable performance boost at 25?.

 

[SparkieBoat]

Re: mercury xr4 150

so when you set it on shore, you set it to 21 right??? (while turning engine over)

 

[rwchop]

Re: mercury xr4 150

took boat out yesterday got up to 50 mph on gps. prop has some dings think it pretty old has no numbers on inside or outside no jackplate i want to say its a 24 pich prop you can just barly make that out on prop i think thats what it says

 

[bk6010]

Re: mercury xr4 150

my 1988 XR-4 150 blackmax on a ranger 18' was sluggish, poor hole shot, sucked fuel. tried different props. I installed a Sting Ray XRIII Senior Hydrofoil Stabilizer a with the original lazer SS prop 24 pitch I was great improvment. however drill and attach to motor. hope this helps. BK

 

[CharlieB]

Re: mercury xr4 150

'Foils' only help hold a boat on plane at low speeds, they actually increase drag and loose top speed unless your set up is so high that you just about surface the prop in order to get the foil out of the water. NOT recommended.

Tune up your motor.