1989 Mercury XR4 Black Max 150 Upgrade Capabilities

[skeletor6]

Hey all,

First post here, been reading around for a while and figured I mind as well join the community.

I recently just purchased a 1986 stratos 179v with this motor on it and everything about it so far has been great. I have been reading through some threads here and I was wondering if there is anyway I could get more HP out of this motor. The guy I bought it from said something about it getting 175hp, but I read a thread here about a 1990 version that puts out about 165 at the prop. http://forums.iboats.com/mercury-mariner-outboards/1990-xr4-black-max-547836.html

Also, in the thread they were designated differences in design between the motor I have and a 200hp version. Is there anyway I can get this boat to run faster, it goes 55mph measured by gps on my fish finder and my phone and I have read of others with this motor getting low to mid sixties.

I had the impeller and water pump in the lower unit replaced by a marine mechanic and the compression check on the motor all were in the range of 119-122.

Any help or comments would be appreciated.

Thank you,

`Skel

 

[ryanskeeter]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

you might could change plugs to like a NGK or maybe get a lil bigger fuel pistons

 

[skeletor6]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

you might could change plugs to like a NGK or maybe get a lil bigger fuel pistons

Thank you Ryan, I will check into doing that. New plugs were put in, but not the NGK's. Is it possible to change the reeds to vertical instead of horizontal and make any carb changes or modifications which were some differences pointed out between the 200 and 150 in the link I provided?

Thanks for your help

 

[glenn property of pam]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

i hate to be the spoil sport as i like fast things but isnt the max power for the 1986 stratos 179v 150hp? If you plan to over power a 27 year old boat i would have the transom checked first. Then i would post the rpm with the motor trimmed lifted to get max speed so the prop guys can see if you are getting the max power from the motor you have already.

Max speed gps
rpm at max speed
prop size and pitch
prop material
prop style (cupped)
number of blades
(skip the last 3 if its a named prop)
do you have a jack plate and is it adjustable?

 

[skeletor6]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

i hate to be the spoil sport as i like fast things but isnt the max power for the 1986 stratos 179v 150hp? If you plan to over power a 27 year old boat i would have the transom checked first. Then i would post the rpm with the motor trimmed lifted to get max speed so the prop guys can see if you are getting the max power from the motor you have already.

Max speed gps
rpm at max speed
prop size and pitch
prop material
prop style (cupped)
number of blades
(skip the last 3 if its a named prop)
do you have a jack plate and is it adjustable?

Its not spoiling anything, I greatly appreciate the information. In fact, I have had trouble finding much information on this motor.

I have had it looked over by a certified mechanic and, for whatever its worth, he said it was in excellent condition after the impellor and water pump was changed.

-There is a jack plate that is adjustable
-Max speed gps is 55mph confirmed on 2 different devices
-prop has 4 blades

The size, pitch and material I do not know at the moment. Also, I still need to get it on the water to find which rpm it is at at max speed, I hadnt paid attention to that detail.

In theory, to get the most out of the motor I have at the moment, would the process begin with getting a specific prop and spark plugs? Or what is the normal order of progression when tuning a motor?

Also, my boat is rated at 150 and I am aware of the dangers of overpowering. Unfortunately, I still want to lol

Thank you for your help and as soon as I get the other information I will post.

 

[Faztbullet]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

Is there anyway I can get this boat to run faster

Dump the 4 blade and go to the bigger gearcase, play with jack plate heights and settings. Draw back is once you get best setup it will only be good for go-fast and fishing as doubt you will be able to ski/tube unless you change settings...

Is it possible to change the reeds to vertical instead of horizontal

It vertical to horizontal and will require motor to be disassembled,line up pins in block removed,new front intake,200 hp cowlings if you have the 2 piece cowls,new front air box,175/200hp carbs,new throttle/carb linkage and you not going to gain but about 25hp unless you port block to 200 specs as port timing is lower. Cheaper to get a 150 SuperMag motor and install...

In theory, to get the most out of the motor I have at the moment, would the process begin with getting a specific prop and spark plugs?

Its a start.....

Or what is the normal order of progression when tuning a motor?

1) plugs
2) Timing and advance module removal, ensure throttle plate are open at WOT
3) dumping none used items from boat example rods,spools of line, plastic & rubber baits, only take what you going to use for that region/season
4) jack plate setting
5) props
What hurts you most is the small diameter gearcase as your limited to blade diameter...

 

[skeletor6]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

Dump the 4 blade and go to the bigger gearcase, play with jack plate heights and settings. Draw back is once you get best setup it will only be good for go-fast and fishing as doubt you will be able to ski/tube unless you change settings...

Thanks for the pros/cons. I won't be pulling anything, just fishing inland Michigan lakes and moving from spot to spot.

It vertical to horizontal and will require motor to be disassembled,line up pins in block removed,new front intake,200 hp cowlings if you have the 2 piece cowls,new front air box,175/200hp carbs,new throttle/carb linkage and you not going to gain but about 25hp unless you port block to 200 specs as port timing is lower. Cheaper to get a 150 SuperMag motor and install...

Sounds simple :faint2: Probably more efficient ways to get more HP

Its a start.....

1) plugs
2) Timing and advance module removal, ensure throttle plate are open at WOT
3) dumping none used items from boat example rods,spools of line, plastic & rubber baits, only take what you going to use for that region/season
4) jack plate setting
5) props
What hurts you most is the small diameter gearcase as your limited to blade diameter...

Made some comments above in red. That was an excellent reply, extremely informative and helpful. I appreciate you taking the time to answer every question I have.

1.) Plugs
-NGK plugs the way to go?

2.) Timing & Advance module removal, ensure throttle plate are wide open at WOT
-Is this similar to the throttle body on a car? Assuming WOT=wide open throttle (I'm terrible at acronyms)......anyways at WOT, the throttle plate should be straight up and down or at a 90 degree angle correct? Or am I just completely off here. If there is a throttle body, should I spray throttle body cleaner on it and scrub it with a toothbrush?

4.) Jack Plate Setting
- I am sure there are articles in regards to this. My jack plate is adjustable, but manually adjustable. Not sure if that makes a difference. I was wondering, in brief, how I would know if my jackplate is adjusted correctly?

5.) Props
-Probably an entire category in itself. In lieu of your opening paragraph, it seems I need to decide on how I want the boat to function. I will be using this boat for fishing only. Mostly lakes under 1,000 acres with the mean being around 500 acres. I love the idea of getting the boat running really well and fast, but is there any negative effects for choosing a prop that is designed for the top end? For instance, would I be fine moving about at 30-35mph, as I read my gps/chart overlay?

Questions

• Q1) Where can I get more information on this motor? As of now, I just have been searching the forums and reading experiences that others have. I cannot seem to find any information on Mercury's website and sense it is so old that is understandable.
• Q2) Is this a 2.4L or 2.0L?
• Q3) In regards to my opening post, if running correctly is this motor rated at 165HP at the prop?
• Q3) Are there any common issues with this motor or others similar that I should be worried about? In other words, is this engine reliable?
• Q4) Is getting a different motor the practical way to add HP to my boat? It is not a huge deal to me, but if there's a way I can get this going 65mph without spending a fortune I would gladly give it a shot.
• Q5) Does 55mph sound about right for my setup? As well as a compression range from 119-122psi?
• Q6) Should I mess around with the carburetor? I have read of individuals getting their carbs rebuilt and such. If the motor is running fine, is there any reason to do anything to it?

Thanks everyone for the help. I realize some of my questions are trivial, but I sincerely appreciate the time and help that has been given. This is my first boat, and I want to make sure that I take care of it well and give it the proper maintenance that it needs.

 

[ryanskeeter]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

okay i dont know why but i have a 17'5"skeeter bass boat and it has a 175 that is highly modified and it will hit low to mid 80's but trust me it is kinda scary going across the lake at those speeds

 

[ryanskeeter]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

i dont understand why your boat is in the mid 50's but it is a long process to get it built up remember Bet On Another Thousand BOAT lol

 

[skeletor6]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

Thanks Ryan. That is extremely fast. I am going to have to do the checks listed and figure out why mine is struggling. Brand new ngk spark plugs have been added and the ones I replaced were ngk plugs as well. Still can't find out the name brand or pitch of the prop but it is stainless steel.

With the correct positioning of the jack plate*and the right prop, how much performance am I likely to gain? And does 55mph for the motor and boat I have seem like it is under performing? Should I be getting higher speeds out of this?

 

[Chris1956]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

What is the pitch of the prop and the max RPM you are seeing? What kind of prop and what shape is it in? How high is the jackplate set?

 

[ryanskeeter]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

Thanks Ryan. That is extremely fast. I am going to have to do the checks listed and figure out why mine is struggling. Brand new ngk spark plugs have been added and the ones I replaced were ngk plugs as well. Still can't find out the name brand or pitch of the prop but it is stainless steel.

With the correct positioning of the jack plate*and the right prop, how much performance am I likely to gain? And does 55mph for the motor and boat I have seem like it is under performing? Should I be getting higher speeds out of this?

all depends on the prop i have a 25 degree pitch 3 blade prop on next to highest setting on the jack plate its a Laser 2 guided prop and it works really well and its not that its under performing it is running well for size but as with any motor it has more power you just have to access it

 

[Faztbullet]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

Questions

Q1) Where can I get more information on this motor? As of now, I just have been searching the forums and reading experiences that others have. I cannot seem to find any information on Mercury's website and sense it is so old that is understandable.
Q2) Is this a 2.4L or 2.0L?
Q3) In regards to my opening post, if running correctly is this motor rated at 165HP at the prop?
Q3) Are there any common issues with this motor or others similar that I should be worried about? In other words, is this engine reliable?
Q4) Is getting a different motor the practical way to add HP to my boat? It is not a huge deal to me, but if there's a way I can get this going 65mph without spending a fortune I would gladly give it a shot.
Q5) Does 55mph sound about right for my setup? As well as a compression range from 119-122psi?
Q6) Should I mess around with the carburetor? I have read of individuals getting their carbs rebuilt and such. If the motor is running fine, is there any reason to do anything to it?

A1) get a factory service manual....
A2) its a steel sleeved 2.4
A3) yes its right at 165 and only issues are cooling and small diameter gearcase. Impeller needs replaced ever 2 year for this engine to live.
A4) best bang for buck is to replace it. It going to be hard to get a 150 to push that boat 65mph
A5) need to know prop type and pitch plus if small or large gearcase but if small gearcase and 20-22pitch prop that about right
A6) no but check linkage to ensure they are opening fully

 

[wired247]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

My 150 HP Merc pushes my boat to 65 MPH ( GPS ) no problem and its only a 2.0 liter. Your'e boat is a little longer and heavier but its a fast hull design.

1. Get the right prop. I get the best top speed out of a 26 pitch small eared chopper with a 2:1 lower. You'll have to find the best for your combo. Don't expect one prop to do everything. One for speed, one for low speed.
2. Cut your heads to get into the 145-150 PSI cranking compression range and use 91-92 octane gas.
3. Fatten the mixture up a bit.
4. Remove the timing module.

 

[Faztbullet]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

17'5"skeeter bass boat and it has a 175 that is highly modified and it will hit low to mid 80's

Must be highly modified and turn over 7000rpm with a 25pitch to get them speeds..... The 17ft Bullet that I sold was a balsa core boat, weighed 950 lbs, lightly modified 200hp, 14.5x28 Triton 2 prop that had been labbed. 18 gallons fuel,2 persons and medium load of fishing gear ran 86-88mph on GPS and out ran a ton of boats that owners boasted that ran 80mph

 

[skeletor6]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

A1) get a factory service manual....
A2) its a steel sleeved 2.4
A3) yes its right at 165 and only issues are cooling and small diameter gearcase. Impeller needs replaced ever 2 year for this engine to live.
A4) best bang for buck is to replace it. It going to be hard to get a 150 to push that boat 65mph
A5) need to know prop type and pitch plus if small or large gearcase but if small gearcase and 20-22pitch prop that about right
A6) no but check linkage to ensure they are opening fully

Thank you for your help. Impeller and water pump were changed this year. How can I tell whether I have a small or large gearcase?

My 150 HP Merc pushes my boat to 65 MPH ( GPS ) no problem and its only a 2.0 liter. Your'e boat is a little longer and heavier but its a fast hull design.

1. Get the right prop. I get the best top speed out of a 26 pitch small eared chopper with a 2:1 lower. You'll have to find the best for your combo. Don't expect one prop to do everything. One for speed, one for low speed.
2. Cut your heads to get into the 145-150 PSI cranking compression range and use 91-92 octane gas.
3. Fatten the mixture up a bit.
4. Remove the timing module.

R1) How can I tell the right prop to get? I am pretty sure I am going to need to get a new one in lieu of previous responses regarding the one I have. I am going to be using this boat for fishing ONLY. I do not have a need to pull anything, basically just going from spot to spot.

R2) Is there any risks involved by cutting the heads? And is this something that I could personally do or should I take it to a mechanic? Also, I've read that fuel with the lowest ethanol content is the best. Is 91-92 octane fuel usually the right choice for that? What will be the result of higher compression readings?

R3) This motor is oil injected. By fattening up the mixture do you mean to set it to mix more oil in with the gas?

R4) Same questions as in the "R2". What exactly will removing the timing module do to engine performance?

Thanks, I look forward to learning more about this engines and outboard motors in general since this is my first boat and I am getting my feet wet. I admire many of the setups that other individuals on this forum have and the help that has been given is extremely appreciative.

 

[wired247]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

Thank you for your help. Impeller and water pump were changed this year. How can I tell whether I have a small or large gearcase?



R1) How can I tell the right prop to get? I am pretty sure I am going to need to get a new one in lieu of previous responses regarding the one I have. I am going to be using this boat for fishing ONLY. I do not have a need to pull anything, basically just going from spot to spot.

R2) Is there any risks involved by cutting the heads? And is this something that I could personally do or should I take it to a mechanic? Also, I've read that fuel with the lowest ethanol content is the best. Is 91-92 octane fuel usually the right choice for that? What will be the result of higher compression readings?

R3) This motor is fuel injected. By fattening up the mixture do you mean to set it to mix more oil in with the gas?

R4) Same questions as in the "R2". What exactly will removing the timing module do to engine performance?

Thanks, I look forward to learning more about this engines and outboard motors in general since this is my first boat and I am getting my feet wet. I admire many of the setups that other individuals on this forum have and the help that has been given is extremely appreciative.

1. Big trial and error thing on the pumps unless you can find someone with a similar setup. Ive tried quite a few and the Solas Titan 4 SS 21 pitch 4 blade has pushed me well into the 60's because its probably more like a 23 pitch in truth. Good and inexpensive enough prop.

2. Risks? You will develop more cylinder pressure and you MUST use higher octane gas. Might be hard to find on the river . I dont buy gas on the river because its old and stale. I buy only 92 octane non ethanol . See what you can get locally and buy the best you can get then adjust your motor to run that if thats what you want. If not, buy the cheap stuff and build your motor to run that.

Buy a set of heads on ebay and have them machined at the machine shop. $200 for the work if you find an expensive marine specific shop that adjusts the cc's for you. 30-32 CC's chamber volume will get you gobs more top end and mid range power.

3. Richen up the A/F mixture a bit if you bump the compression.

4. In addition to stabilizing the idle, part of what the timing module does is reduce timing on the top end past 5200 or so. Screw that. You want full timing on the top end. That probably the first change you should make. Costs nothing but a few hours of your time adjusting the timing.

 

[skeletor6]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

Thank you Wired!

R1) Since it is trial and error, would getting the Solas Titan 4 SS 21 4 blade be a good "trial" for my first prop?

R2) I will try to find some sources of ethanol free fuel. I usually just fill up at the gas station and hearing that ethanol content is higher in premium gas I use the lower octane fuel. I have ran it with both to see speed differences. Roughly, what would this process cost?

R3) So should I adjust the timing, or remove the timing module all together?

Additional question, where do I find mercury service manuals for this motor?

Thank you for your help!

 

[wired247]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

Thank you Wired!

R1) Since it is trial and error, would getting the Solas Titan 4 SS 21 4 blade be a good "trial" for my first prop?

R2) I will try to find some sources of ethanol free fuel. I usually just fill up at the gas station and hearing that ethanol content is higher in premium gas I use the lower octane fuel. I have ran it with both to see speed differences. Roughly, what would this process cost?

R3) So should I adjust the timing, or remove the timing module all together?

Additional question, where do I find mercury service manuals for this motor?

Thank you for your help!

1. I just recommend that prop because in my experience it is a very smooth running efficient prop capable of better than expected speed number with little slip. I run a 150 and use mine on there and have used the same prop on a 225 and a 260. It would easily go 75 MPH with that prop and would probably go faster if my hull was good for it. It is the most drama free prop I have ever run. I have "errored" with other props. Many other props.

2. Some people really dont like ethanol fuel. I dont think it matters much if you cycle through the stuff fast enough. Old ethanol gas is crap but with good fuel lines you dont need to worry much with fresh gas. What will matter if you cut the heads is the octane and if you get in the 140 psi cranking compression range you WILL need 91-92 octane whether its 10 % ethanol or straight gas.

As far as price you can get a set of heads under a hundred bucks so you can keep our originals in case you want to go back or sell it later. $100-$200 for the head shaving. Mine cost $130 to have done but it was at the local NAPA machine shop and mine got down to 28 CC's as I have a 2.0 a had to take more off and cc them between cuts. Theres a number of vendors over on screamandfly that will cut your heads for $200 . You can often buy a set on their classifieds that have been cut already for $200 ish.

3. There is no adjusting the stock timing module. Remove it and set the idle timing and WOT timing with a timing light.

4. ebay

 

[Faztbullet]

Re: 1989 Mercury XR4 Black Max 150 Upgrade Capabilities

R3) This motor is fuel injected.

If its a Xr4 its a carb engine, if fuel injected the only way to fatten it up is to buy a adjustable ECU...

R1) Since it is trial and error, would getting the Solas Titan 4 SS 21 4 blade be a good "trial" for my first prop?

4 blades are slower than a 3 blade but handle better and add a little more lift to transom..sti;; need to know if you have small or big gearcase and pitch of old/new prop...