I can't tell you exact, because I was not paying that much attention but the 26 runs at about 5500 at about 55 mph (GPS) and the 21 runs at about 5800 at about 46 mph (gps)
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What's wrong?
- Thread starter camoto
- Start date
BullittBen
Member
My 17' V-Mate II with a '75 115 (only 90 hp by later ratings), no power trim, a 19p Vortex aluminum prop (which was too much) and a 6" manual jackplate (plus 1" spacer) raised about 3" will pull a skier up with baggy pants on a wake skate. I've never tried anyone on regular skis, but that was a pretty bad combination. We don't ski much.
The jackplate isn't hurting you much, but it may scoop some water when all the way down (hence the need for those "holeshot plates"). That may be why some boats do better with it up a little.
Something isn't right. Boston said sometimes he had to lean over the windshield to get on plane. I don't even have to do that with mine loaded to the gills and no power trim. If I stomp it, it's on plane even with neutral trim.
The whole problem may be setup, because like you said, if it will run top end I would think the motor is OK. My boat is lighter than yours, but even with a dead cylinder, you should have more power than me.
The jackplate isn't hurting you much, but it may scoop some water when all the way down (hence the need for those "holeshot plates"). That may be why some boats do better with it up a little.
Something isn't right. Boston said sometimes he had to lean over the windshield to get on plane. I don't even have to do that with mine loaded to the gills and no power trim. If I stomp it, it's on plane even with neutral trim.
The whole problem may be setup, because like you said, if it will run top end I would think the motor is OK. My boat is lighter than yours, but even with a dead cylinder, you should have more power than me.
That's good info, thanks. Although I am leaning even more towards a motor/power issue after hearing that.....
groucho
Member
Propping a boat correctly is not an exact science as you are finding out. More of an art really. Your top end #'s w/the 26" are pretty much in the range both speed and RPM -wise for what you might expect for your rig, set-up and prop.
So are your #'s for the 21". Which you are now saying " tell me something I don't already know".
Based on your need Here is what I would try. See if you can find a Mercury dealer in your area that has " Demo" props available. I know that sounds like a bit of a stretch but here's my thought. You need about a 20" pitch 4 blade ( Merc calls them an Alpha prop) to see what results you might have pulling out a skier. It will allow that cross-flow V6 to wind-up more quickly and punch out of the hole. It will also allow you to test a prop without buying it. Just ask them to put an OMC hub in it.
The other case would be a 5 blade "High Five". It WILL come out of the hole but your top end is greatly diminished. Plus it only is sold as stainless steel.
The simple rule to remember in propping is...for each blade typically that you add you gain in acceleration but lose in top end. But some props might work wonders in both.
I have a 20" 4 blade on my 175 Merc ( 18.5 ' Eluder ) for cruising and skiing and a 24" Yamaha drag prop for holeshots/speed and a 24" Chopper for top end.
So are your #'s for the 21". Which you are now saying " tell me something I don't already know".
Based on your need Here is what I would try. See if you can find a Mercury dealer in your area that has " Demo" props available. I know that sounds like a bit of a stretch but here's my thought. You need about a 20" pitch 4 blade ( Merc calls them an Alpha prop) to see what results you might have pulling out a skier. It will allow that cross-flow V6 to wind-up more quickly and punch out of the hole. It will also allow you to test a prop without buying it. Just ask them to put an OMC hub in it.
The other case would be a 5 blade "High Five". It WILL come out of the hole but your top end is greatly diminished. Plus it only is sold as stainless steel.
The simple rule to remember in propping is...for each blade typically that you add you gain in acceleration but lose in top end. But some props might work wonders in both.
I have a 20" 4 blade on my 175 Merc ( 18.5 ' Eluder ) for cruising and skiing and a 24" Yamaha drag prop for holeshots/speed and a 24" Chopper for top end.
So it sounds to me that your belief is that there is nothing wrong with the engine or how it is tuned?
Is there any way I could DEFINITIVELY rule out an engine problem or not and simply focus on the actual cause of the problem?
Before you even start with set up. Get that motor running properly.
First off, if all you have done if reeds and velocity stacks you have gained allmost nothing. No gain from slightly oversized pistons. If your motor was 150hp you probably have 155 now.
First off, as someone else said, check compression, leakdown, and spark etc first. As you've said it runs fine on top end I doubt fuel delivery.
Is the tuner stock? The 2.0l has a long tuner and lots of guys change them out for the shorter one for top end which kills the bottom end, much like the problems you are having. Velocity stacks are a complete waste of time. Take them off and put the stock air box back on and tune your carberation from stock as described in the Boyeson reed literature. (If all that is done is reeds..i.e no cut heads etc.) Depending on the year of the motor mid-late
80's V-6 Merc's had several other issues that could effect holeshot which were detailed in several service bulletins. Things like preloaded reeds, bleeder valves etc.
You will never swing a 26" with that setup, much less ski with it.
First off, if all you have done if reeds and velocity stacks you have gained allmost nothing. No gain from slightly oversized pistons. If your motor was 150hp you probably have 155 now.
First off, as someone else said, check compression, leakdown, and spark etc first. As you've said it runs fine on top end I doubt fuel delivery.
Is the tuner stock? The 2.0l has a long tuner and lots of guys change them out for the shorter one for top end which kills the bottom end, much like the problems you are having. Velocity stacks are a complete waste of time. Take them off and put the stock air box back on and tune your carberation from stock as described in the Boyeson reed literature. (If all that is done is reeds..i.e no cut heads etc.) Depending on the year of the motor mid-late
80's V-6 Merc's had several other issues that could effect holeshot which were detailed in several service bulletins. Things like preloaded reeds, bleeder valves etc.
You will never swing a 26" with that setup, much less ski with it.
groucho
Member
I gave you a bit of mis-information. Your first post said " OMC" and I had that in my head as kept reading on. Somehow I missed the 2.0 liter part. Sorry for the mistake. But my prop analysis is still the same. And frankly I doubt that a motor that's down on a bad cylinder would start, idle, or perform the way you describe.
A bad cylinder would give you rough idling, hard starting, and top end that would NEVER turn that 26" the way you are now.
So I still say try the 20" 4 blade before you start tearing apart an engine and switching tuners.
Also check your spark plug color. All of them should be a nice chocolate brown color. The sign of a motor that's dialed in right.
A bad cylinder would give you rough idling, hard starting, and top end that would NEVER turn that 26" the way you are now.
So I still say try the 20" 4 blade before you start tearing apart an engine and switching tuners.
Also check your spark plug color. All of them should be a nice chocolate brown color. The sign of a motor that's dialed in right.
Boston Predictor
Well-known member
My suggestion for the gas tank might not be "practical" in "your" case, but it sure isn't "plain" stupid.....It would help...
Xsive knows what he is talking about here. The motor was built for top end speed so the parts used may be killing the holeshot. I know it has a diffrent tuner as well.
Camoto, Ill PM you my mechanics cell # and you can talk to him about the work he did. He is a merc genius and will explain every detail of that motor....
The thing I find strange is I was able to turn a 28 chopper close to 6,000rpm and the holeshot was way better than ANY other prop I tried. Can anyone explain that???
Xsive knows what he is talking about here. The motor was built for top end speed so the parts used may be killing the holeshot. I know it has a diffrent tuner as well.
Camoto, Ill PM you my mechanics cell # and you can talk to him about the work he did. He is a merc genius and will explain every detail of that motor....
The thing I find strange is I was able to turn a 28 chopper close to 6,000rpm and the holeshot was way better than ANY other prop I tried. Can anyone explain that???
excellent posts, thanks to both of you. I am going to try the following and see if I get any results:
1.) Compression re-test (just to be sure)
1a.) plug color check
1b.) spark check
2.) Fuel delivery (possibly an upgrade to electric??)
Hopefully that yeilds something because it does not seem that setup is the issue as a 21p prop should have shown SOME sign of improvement (I would think)
1.) Compression re-test (just to be sure)
1a.) plug color check
1b.) spark check
2.) Fuel delivery (possibly an upgrade to electric??)
Hopefully that yeilds something because it does not seem that setup is the issue as a 21p prop should have shown SOME sign of improvement (I would think)
Sorry Boston, I didn't mean your suggestion was stupid, I meant that it would be stupid if that's what I HAD to do just to pull a skier.
Boston Predictor
Well-known member
I know, Im just as confused by this rig as you are
If you run the numbers that he is getting on that 26 it is 23% slip....Something aint right. On a V-6 often times a dead cylinder is almost impossible to distinguish at an idle. It will start and idle well, but when you put the coals to it..BBLLAA!!
You should not have to upgrade to an electric fuel pump. If you think it is a fuel delivery issue, check the pick up for an anti-syphon valve and either replace or turf it, replace fuel pump diaphragm, and use a genuine MERCURY primer bulb. Unless you are pulling fuel from 20' away (front of the boat, the regular fuel pump is sufficient. The mechanical fuel pump is simple and works, no wires, to pressure regulators to adjust.
Before you go beyond the basics wait until BP finds out this motor has for mods, then set a plan of action. Don't get the cart in front of the horse.
BP,
The reason why your 28" chopper worked better on the holeshot was because if what I suspect about the setup of this motor is correct, (Peaky power) the over-the-hub exhaust allows the motor to spool up quickly by creating slip. It goes from 1000RPM to 5500... like now!!!. You are spending almost no time in the 1000-3500RPM range to plane. A normal through hub prop, even using PVS vent plugs, still has to wind its way up through the RPM's.
Boston Predictor
Well-known member
What has been done to the motor:
Engine bored .30 over
New pistons/rods
Heads milled
ports raised
stage 3 reeds
Velocity stacks
changed from a 25'' to a 20'' mid
New tuner
bobs nosecone
compression-145 to 150psi
Im still confused why the 28hoss was MUCH better than the 26hoss out of the hole...maybe the extra cup in the blades? I understand about slip and rev time but im still baffled
Engine bored .30 over
New pistons/rods
Heads milled
ports raised
stage 3 reeds
Velocity stacks
changed from a 25'' to a 20'' mid
New tuner
bobs nosecone
compression-145 to 150psi
Im still confused why the 28hoss was MUCH better than the 26hoss out of the hole...maybe the extra cup in the blades? I understand about slip and rev time but im still baffled
Someone over at scream and fly suggested a sync and link while I am checking compression, spark and fuel. Does anyone know if I can get semi-detailed instructions for this online?
One new detail, probably nothing though:
I noticed last night when I took the covers off that there was a metal spring that looks like a big C that one side hooks into the block and the other side hooks into the linkage on the large pivot that was disconnected and just hanging there. I don't think it was affecting operation of anything, but I fixed it just to be sure.
I will be doing the compression and spark test tomorrow night, I have an extra set of hands coming over to help out.
One new detail, probably nothing though:
I noticed last night when I took the covers off that there was a metal spring that looks like a big C that one side hooks into the block and the other side hooks into the linkage on the large pivot that was disconnected and just hanging there. I don't think it was affecting operation of anything, but I fixed it just to be sure.
I will be doing the compression and spark test tomorrow night, I have an extra set of hands coming over to help out.
What octane gas were you running in it.....??? Could it be this simple? I should have my own compression numbers thursday night, but I know from dealing with dirtbikes for so long that if you get the compression high enough, a two stroke single will run like crap on working-man's gas.
I think I may have found the problem, but I am still stuck.
While I was checking the first cylinder, I noticed, no spark. So I checked the others:
#6 - No Spark
#5 - Spark
#4 - No Spark
#3 - No Spark
#2 - Spark
#1 - No Spark
I then noticed that the leads that go to the coils seemed dirty, so I took them off of 5 & 6 and cleaned them. Then, I got spark on #6. So then I go and clean 4 & 3 and no spark still on 4, so I recheck 6... no spark again. So then I move to 4, and I have spark....wtf. Then I check 1 and I have spark. At this point I have the blow torch ready. After cleaning contacts and fiddling with it, this is what I come up with:
#6 - Intermittent Spark but mostly dead
#5 - Consistent Spark
#4 - Intermittent Spark but mostly dead
#3 - Never any Spark
#2 - Consistent Spark
#1 - Intermittent Spark but mostly dead
Does this make any sense? What baffles me even more now is how it runs healthy when revved. Maybe something to do with low voltage somewhere? At the end of this before I almost lost my mind I even charged the battery back up and went back to find the original (at the top) findings. I was using a Ignition Spark Tool and had it gapped very small just to see if any of these were just weak. I don't think I could have got it closer without it being touching.
How does this motor even start?? What should I assume now?
While I was checking the first cylinder, I noticed, no spark. So I checked the others:
#6 - No Spark
#5 - Spark
#4 - No Spark
#3 - No Spark
#2 - Spark
#1 - No Spark
I then noticed that the leads that go to the coils seemed dirty, so I took them off of 5 & 6 and cleaned them. Then, I got spark on #6. So then I go and clean 4 & 3 and no spark still on 4, so I recheck 6... no spark again. So then I move to 4, and I have spark....wtf. Then I check 1 and I have spark. At this point I have the blow torch ready. After cleaning contacts and fiddling with it, this is what I come up with:
#6 - Intermittent Spark but mostly dead
#5 - Consistent Spark
#4 - Intermittent Spark but mostly dead
#3 - Never any Spark
#2 - Consistent Spark
#1 - Intermittent Spark but mostly dead
Does this make any sense? What baffles me even more now is how it runs healthy when revved. Maybe something to do with low voltage somewhere? At the end of this before I almost lost my mind I even charged the battery back up and went back to find the original (at the top) findings. I was using a Ignition Spark Tool and had it gapped very small just to see if any of these were just weak. I don't think I could have got it closer without it being touching.
How does this motor even start?? What should I assume now?
Chris E
Well-known member
so how do you like boats so far?????!!!!!!
ok - time to get out the service manual - need to have a look see at the electrical system - coils could be week - check that stator though - it was the last electrical part repaired - the absolute first place i'd look. also check the powerpacks - there are 2 one behind the other. don't go any farther until you have a multimeter and a service manual.
i hate to ask - but you did have a good ground when you were testing the spark right?
how was compression?
ok - time to get out the service manual - need to have a look see at the electrical system - coils could be week - check that stator though - it was the last electrical part repaired - the absolute first place i'd look. also check the powerpacks - there are 2 one behind the other. don't go any farther until you have a multimeter and a service manual.
i hate to ask - but you did have a good ground when you were testing the spark right?
how was compression?
groucho
Member
You seemed to have found the problem. But as for why it does so much, so well I too say...WTF.
Are the plugs themselves burning the right color or are they fouled? If they are fouled that will account for some or all of the " no" or part-time" spark.
I can't imagine an engine that will turn 5600 RPM that will run on 3-4 cylinders.
Try switching the plugs that have good spark with the ones that have none and see if you have the same results. I know this seems like grasping at straws but it's part of eliminating the basics.
What was your compression check results?
Are the plugs themselves burning the right color or are they fouled? If they are fouled that will account for some or all of the " no" or part-time" spark.
I can't imagine an engine that will turn 5600 RPM that will run on 3-4 cylinders.
Try switching the plugs that have good spark with the ones that have none and see if you have the same results. I know this seems like grasping at straws but it's part of eliminating the basics.
What was your compression check results?