1987 evinrude xp150 not getting all rpms??

[Doemaster62]

I recently bought a 1991 venture dominator w/ a 1987 evinrude xp150. when purchased the owner told me that he hadnt run the boat in approx. 6 months but knew the boat ran well... After purchase, i had the carbs rebuilt, and 1 of the power packs replaced being as the other had recently been done. plugs have been changed also. When i purchased the boat the owner told me that he had gotten speeds in the low 70's at approx 5800 rpms. I recently ran the boat and the best i could get was 55 mph(gps) at 5000 rpms. The motor is running a 14 1/2x22p prop (raker ss) and 4" jack plate (set closer to the bottom). I can hit the hot foot and it will tach out, but when im running it will not get over 5000. It also has a slight pull to the right when i run it (i was told this is due to engine torque). I also noticed that the jack plate had been adjusted and someone had attempted to re-drill hole to gain more trim. Is there anything i can try to get my rpms and speed back?

 

[Doemaster62]

Re: 1987 evinrude xp150 not getting all rpms??

i also replaced that power pack because it went out...forgot to mention that... thanks in advance

 

[emdsapmgr]

Re: 1987 evinrude xp150 not getting all rpms??

The engine is not turning the correct rpm's. You need to look at your setup. I'd prop that engine to run in the 5600 to 5800 rpm range. Either you have too much prop for the engine or it may be down on hp for some reason. Make sure the jack plate is raising the engine high enough. (are you running a water pressure gauge?) It is normal for higher hp engines to pull to the right with conventional steering cable setups.

 

[Doemaster62]

Re: 1987 evinrude xp150 not getting all rpms??

I had been told that my issues where probably with the prop and jackplate setup. This is the first boat ive owned but have been around them all of my life... I know several quality marine mechanics and they had told me to try prop and jackplate adjustments, but i am worried about making to many adjustments due to the fact that I am not running a pressure gauge... I will definatly be getting one now. I have also been told to invest in a good hydrofoil...I have looked into the stingray XRIII due to my boat being so light...Is this a worth while investment?

 

[wilde1j]

Re: 1987 evinrude xp150 not getting all rpms??

No. It will slow you down a few MPH.

 

[Doemaster62]

Re: 1987 evinrude xp150 not getting all rpms??

Thanks, thats what i needed to know...

 

[emdsapmgr]

Re: 1987 evinrude xp150 not getting all rpms??

Start by checking the engine height. When on plane and trimmed out, you want the water flowing under the bottom of the transom to be at, or just under the antiventilation plate of the lower unit. Note your speed and rpm and type of prop used. If the engine is lower than that, you will get excess water spray and excess drag. Testing some hi-rake props will permit you to raise the engine higher-reducing the lower unit drag in the water and gaining speed and performance. Each time you make a change, record your speed and rpm's and which prop you used. As you raise the engine up from your initial setting, you will need to keep an eye on your engine water pressure and temps. (you will need a 0-30 lb pressure gauge.)

 

[walleyehed]

Re: 1987 evinrude xp150 not getting all rpms??

Tell me a bit about your boat...hull design, intended use, length, etc...
I'll give ya a rule of thumb for heigth but I need to know the hull type first. (Pad-bottom bass, deep-V, etc)

 

[Doemaster62]

Re: 1987 evinrude xp150 not getting all rpms??

well the boat is an 1991 venture bass boat (18'), it is similar to a v-hull, but at the bow its almost like a tri-hull, but the tri never gets to the vee. I tournament bass fish alot so i need the speed (or as much as i can get) but also need decent fuel economy. I am running a 1987 evinrude xp150 (vro removed) w/ a 3x14.5x22p raker...the jack plate is like a 4-5", but not sure which. It has been drilled before and appears to be back in the original holes. it is set approx. 1/2 mabey a hair closer to the bottom(had previously said closer to top but rechecked this morning and confirmed placement). When i got the boat, it had a port side power pack out. After replacing this, at WOT i am running 5000 rpms at 55.4 gps mph. Also when i bought the boat it had ngk plugs in it, have now switched to the factory recommened champion plugs due to the ngks fouling constantly, but i have made 2 trips on the champs and the still look dry and pretty much new...

 

[walleyehed]

Re: 1987 evinrude xp150 not getting all rpms??

If the jackplate is a 5" or whatever...measure the distance from the transom where it meets the hull bottom (more forward if it has a step) straight across to the leading edge of the lower unit with the engine trimmed down to the "level" position. Post this measurement. You would want to measure the jackplate as well, from the transom-back, so we know what it is.