1989 Stratos xr4 150

[Davidsr61]

Everyone telling me a 24 pitch should be about right for the boat. I have a trophy plus on it now and i can't turn 4900 rpm maybe 5000 if i try hard. The jack plate was set at 4 1/2 below the pad and i have raised it to about 3 inch below the pad and I think i have lost speed and didn't gained any on the rpms either. Is it something else i need to look at? The hole shot not bad and running half throttle pretty good too. with the motor down i was running 40 mph at 3500 rpms

 

[Silvertip]

Re: 1989 Stratos xr4 150

Ummmm -- yup! Is the engine properly tuned and making full power? Throttle opening fully? If the engine isn't making full power the jack plate and prop cannot be faulted for poor performance.

 

[steelespike]

Re: 1989 Stratos xr4 150

If your not having any ventilation(cavitation) issues the motor is likely too low.
You should raise the motor till it ventilates too easily then lower to a point where
venting isn't an issue.This may or may not solve your problem.
Is the bottom clean and smooth? What is your speed at 5,000?

 

[SparkieBoat]

Re: 1989 Stratos xr4 150

size and approx weight of your boat would help... also are you saying you have raised your motor 1 1/2 inches and no change?? you must be way too far down. keep raising it up like steel said. is it a 25" shaft motor?? you probably can get your RPMs to over 5500 once you get to the right height...assuming your motor is in proper running condition.

 

[Davidsr61]

Re: 1989 Stratos xr4 150

It is 1989 285 pro. the weight of the boat is 1398 boat only. the shaft is 20 inch long. At 5000 rpms i hit about 50 mph. The motor been rebuilt right before i got the boat. It sounds like it running good and no miss in it at all. Half to 3/4 throttle it run pretty good but after that it just don't do anything in speed or rpms. Before i rised the motor it would run 40 mph at 3500 rpms now after i risd it it does 40 mph 4000 rpms and that just a little over half throttle. Could it be in the timing or the prop just to much for the boat?

Thanks for any help at all

 

[SparkieBoat]

Re: 1989 Stratos xr4 150

before addressing prop issues you need to make sure your motor is in tip top condition...checking compression, spark, timing, fuel pump, carbs, lines, linkage...after that is all checked out ok then you can look at getting a lower pitch prop to get your RPMs to 5500-5800...I would also see if I could raise the motor any more, you want it as high as you can get it with out it venting.

 

[Davidsr61]

Re: 1989 Stratos xr4 150

Ok I just finished checking the compression and all are at 125 to 130. The timing was at 8 at idle and the fast time was at 17 btdc and the little box been removed. I set it at 11 atdc and 23 btdc. I will try it out tomorrow. I hope it make a difference.

 

[SparkieBoat]

Re: 1989 Stratos xr4 150

where did you get the timing specs?? make sure they are for your motor. the 11 ATDC sounds high..I thought that was supposed to be 4-8...also did you subtract 4 degrees on the WOT timing since you did that static??? you do not want to advance timing too much or you may pop a piston.

 

[Davidsr61]

Re: 1989 Stratos xr4 150

That what i found on 2 different broads for a 1989 xr4 150 with taking off the advance box.. I guess i better be looking more.

 

[Davidsr61]

Re: 1989 Stratos xr4 150

That one thread on here and it was that j_martin
Admiral post on this Thread: 1988 mercury 150 xr4 carb cleaning

 

[KDAVID1]

Re: 1989 Stratos xr4 150

I have a 1993 Merc 150hp black max--25p 3 blade on Ranger 354V-5500RPM top speed 68mph.
Boat is 18ft. But this may not be helpful as mine is XR6.

 

[Davidsr61]

Re: 1989 Stratos xr4 150

where did you get the timing specs?? make sure they are for your motor. the 11 ATDC sounds high..I thought that was supposed to be 4-8...also did you subtract 4 degrees on the WOT timing since you did that static??? you do not want to advance timing too much or you may pop a piston.

You are right it say 7 atdc on idle and it say 22 btdc and the advance module will take it to 26 btdc So does anyone know do i go to 26?

 

[SparkieBoat]

Re: 1989 Stratos xr4 150

you should be right with your timing then...but when setting it static you need to subtract 2-4 degrees...if you removed the idle control module, which is recommended to do, you should set WOT timing to 25 BTDC and 22-23 static.

 

[Davidsr61]

Re: 1989 Stratos xr4 150

Thanks...i guess i need to go down to 23 pitch at least. With all 3 of us in the boat it still only run about 49 and tuning 4900 rpms. but with just me it did 57 and tuning around 5400 rpms and im talking and about a short run

 

[SparkieBoat]

Re: 1989 Stratos xr4 150

that is a pretty big difference for 2 people. I usually only see a 2-3 MPH and 200-300 RPM difference with 2 adults added. you could drop 2 pitches from your current easily. but first you may want to try raising your motor a couple of holes up. as I mentioned in post 6, this could make a huge difference.

 

[Davidsr61]

Re: 1989 Stratos xr4 150

Well the 2 that got out was around 340 pounds. After they got out it like the boat came on top of the water and took off. the motor about 3 5/8 below the pad now. would raising it make that much differences

 

[Dhadley]

Re: 1989 Stratos xr4 150

A Stratos will benifit from a prop with bow lift. The Trophy will not supply much bow lift, you might try to find a bow lifting prop to try. Without the lift you might be dragging a lot of hull. That's why the weight difference was so apparent.

 

[Davidsr61]

Re: 1989 Stratos xr4 150

Which one would be a good prop for the boat? and would you still go with a 24 pitch or go down too
Thanks
David

 

[SparkieBoat]

Re: 1989 Stratos xr4 150

raising the motor could make a huge difference...it could change the pitch prop you need for sure..I would try raising it before ordering a prop, you might be real surprised with the results.

 

[Davidsr61]

Re: 1989 Stratos xr4 150

Ok i will give that a try. how high can i go before water pressure drops.
thanks for the help
David