1991 Evinrude 150 xp...4500 max Rpm

[Bostonmatt]

I have a 91 150 xp. All three carbs rebuilt. New coils, power pack, and plugs. New fuel lines, and battery. Boat pulls strong out of hole, punches right up to speed. But seems to only make around 4500-4800 rpms. What is best way to check tach to make sure it is correct. Prop is a 14. 5 inch 23 pitch, went to a 21 pitch and nothing changed.Also What about best way to time engine? . Engine seems strong compression is equal @ 90 psi per cylinder. How tough is it to locate a test wheel so I can run engine in huge barrell so I can make apropriate adjustments? Thankyou in advance for any info.

 

[emdsapmgr]

Re: 1991 Evinrude 150 xp...4500 max Rpm

The compression is fine. Normally you will pickup about 300 rpm when you go down a prop size. Interesting that you did not. Is the tach set correctly on 6? Have you checked the carb butterflys to make sure they are full open at full throttle. When at full throttle is the timer base at full advance? You can check the timing on the trailer. Undo the link arm to the timer base and advance it to max, then check #1 and #2. This static test will usually yeild 3-4 degrees lower than the decal on the airbox cover.

 

[Bostonmatt]

Re: 1991 Evinrude 150 xp...4500 max Rpm

Thank you for your reply. I just readjusted the cab butterflies, lowered the maximum throttle screw, connected all six plug wires to sparker, pulled plugs and at wide open throttle the max spark advance was 26-28* above dtc. the book says 31-33... I moved it up to 32*. checked my idle timing at 6-8 dtc and was right on money. Book says max rpm is 4500-5500 Id love to see 5200. I will check everything else and run her this weekend. Does it sound like I missed anything or should change/add/subtract anything? Thank you again for your time.

 

[emdsapmgr]

Re: 1991 Evinrude 150 xp...4500 max Rpm

I'd recheck your timing. Remember that when you get the engine back on the water, the characteristic of that ignition system is that it will gain up to 4 degrees of timing at 5000 rpm over the static test max timing. Make sure you don't exceed your factory stated max advance and toast the engine when running down the lake. Next time you are running at your max rpm, turn off the key and immediately put it in neutral. Pull each plug and check them. Are they all the same color...are any of them washed in appearance? You need to get the engine up to 5500 to 5700. You are lugging it below 5400. Check your setup-is the engine too mounted to low on the transom? Is the tach set on the correct setting? Are the carb butterflys opening fully?

 

[d.boat]

Re: 1991 Evinrude 150 xp...4500 max Rpm

Are all 6 firing?

 

[Bostonmatt]

Re: 1991 Evinrude 150 xp...4500 max Rpm

I will retard the spark down 4 degrees, butterflies apear to be now opening fully, I am getting spark at all six plugs, all plugs apear equal in appearance. I will have to review tach set up. Motor is mounted on adjustable transom bracket... wide open she is just underwater...j water level ust below hydrofoil. If i trim her up she throws a roostertail, but rpms stay the same. I will down load tach manual and check that......is there a faactory rev limiter? I looked at tops of pistons with flashlight..all seem equal in apperance.

 

[emdsapmgr]

Re: 1991 Evinrude 150 xp...4500 max Rpm

The power pack will rev limit at 5800. A double check on the accuracy/setting of the tach is a good idea. Sound like you have the engine mounted about right. Marine tachs have an adjustable setting on the back. What is your set to?

 

[Bostonmatt]

Re: 1991 Evinrude 150 xp...4500 max Rpm

tach replaced and now we are getting 5200-5300 max rpm. Boat did about 55 with two guys full fuel, she runs great and strong wide open, she sounds a little ruff at 2500 rpm. She also sounds like she may be miss firing. WOT she runs great. Thought there would be higher rpms. Can ever get her over that

 

[emdsapmgr]

Re: 1991 Evinrude 150 xp...4500 max Rpm

Those engines have a lot of torque. You may be propped pretty close to optimum. Check the top end and max rpm's with just you in the boat and a light load of gas. You want to be right at 5500-5700 with a light load. If you can't get there, you may want to go down a prop size.

 

[Bostonmatt]

Re: 1991 Evinrude 150 xp...4500 max Rpm

will try. Can I use static timing to set low end timing...and if so should I set it at 10* TDC. The manual says 6-8tdc. But it seems static timing is 4 degrees ahead. Whats the difference btween a three and four blade prop, stainless and aluminium. Anyway to check the hieght of the prop in relation to the transome. Is this about what the boat would normaly do for speed. 175 nitro, with a evinrude 150 xp tracker pro series. Thanks again

 

[emdsapmgr]

Re: 1991 Evinrude 150 xp...4500 max Rpm

The factory idle timing is an estimate to use when first starting the engine. You need to adjust the idle screw yourself to set the idle timing at 650-750 in gear when the boat is floating normally in the water. Because different engines sit at different depths (on the transom) on boats, the actual idle timing will vary by boat applications. When you get into high rake stainless props, you have some setup options. These props will maintain their bite even if the engine is mounted slightly higher on the transom. Less engine in the water=more speed. 4 blades props are good for heavier boats like bass boats as they tend to increase bow lift (and perhaps speed) at top end.

 

[jonesg]

Re: 1991 Evinrude 150 xp...4500 max Rpm

I'd say prop, my 150 is propped with a 14x19.
With my prop you'd get 5600 if you wanted.