1987 XR2 150 Q's

**croSSed** · 08-19-2010, 06:03 PM

This thing runs perfect, however it can be kind of finicky in that it is hard to keep it at specific throttle position at times, like skiing speed. Eg., it doesn't want to hold a steady speed at about 3400-3600 rpms. It will settle below this (3000-3200) or above this (3800 and above). Is there ANY thing I can do to get it to settle in at that throttle setting? There are other settings it doesn't want to hold too, like just barely on a plane. Doesn't want to stay there, and doesn't SOUND like it wants to stay there.

Also... I'd like this thing to have more TORQUE. I'm a slalom skier, and a big guy (6'6", 240+). It will pull me up, but I have to wait longer than I'd like. Are there any bolt on mods I can do to get more pull out of the hole? Thanks folks!

TG

**fyremanbil** · 08-19-2010, 11:28 PM

You'll have the best luck trying different props. An afterplane, like dolefin or one of the many others, can really help plane a boat.

**croSSed** · 08-20-2010, 04:22 PM

Originally Posted by fyremanbil

You'll have the best luck trying different props. An afterplane, like dolefin or one of the many others, can really help plane a boat.

Thanks for the reply. I have tried different props. I tried a 20 and a 21P High Five and the issue I described above was REALLY bad! The boat came up on a plane so fast I could feel the g's, but couldn't ski with it because it wouldn't hold a steady speed AT ALL. A 25 pitch High Five might help w/ the steady speed issue, but I doubt my boat would pull me up with one of those, or at least it would take a loooooonnngggg time. Frankly, I would never put a dolefin like product on any boat I own. I think it mutilates your motor, and it causes you to lose top speed. There's got to be a different way to get more pull out of the hole. Well, I could slap an XR6 drop-on powerhead on my motor, but the budget won't allow for that.

TG

**sschefer** · 08-20-2010, 04:49 PM

There are two things, neither of which are prop related, that can cause your problem. The first is fuel delivery issues (which I doubt) and the second is ignition systems. A failing high speed stator ignition coil. The low speed coils carry over into the high speed coil range quite a way's but eventually stop producing adequate voltage to fire the spark plug coil. If the high speed coil is not comming on until later than normal there would be a very small but often consistent point where there's just not enough voltage being sent to the switchbox to fire sparkplug coil. When this happens it's usually just one of the high speed coils and only affects one switchbox.

The only way to test this is in the boat under power with two DVA's. You need to watch the low speed coils and the high speed coils at the RPM's where this is occuring to determine if it is the problem or not. Hard to say which is easier, the test or just swapping it out with a known good stator.

**TEXAS20225** · 08-20-2010, 05:05 PM

I believe the XR2 is a 2.0 liter motor they do not have much torque you need less pitch not more pitch try a 17 or 18 5 blader you will be surprised. dole fins are ugly but they dont slow you down they are out of the water when on plane

**transomstand** · 08-20-2010, 05:54 PM

Your problem is not the engine, except for being a bit underpowered. The "problem" is the hull. Every hull wants to take a "set" at planing speed, it will always "seek" it. The best way to change it is, as mentioned, with a doelfin type device, or a major change in balance to the hull.

You cannot force the engine to maintain a transitional rpm, the hull wants to go faster or slower, and the engine cannot overcome that, no matter how powerful. It's like setting your car's idle at 2000 rpm, then try to maintain it on a hilly road, you just can't do it.

**croSSed** · 08-20-2010, 08:34 PM

I believe the XR2 is a 2.0 liter motor they do not have much torque you need less pitch not more pitch try a 17 or 18 5 blader you will be surprised. dole fins are ugly but they dont slow you down they are out of the water when on plane

Yes, it is a 2.0L motor. You miss the point about the speed issue. Like I said, with a 20 or 21P High Five the boat was UNREAL out of the hole, but... I could not get it to hold a steady speed at skiing speed to save my life. I imagine that if I went even smaller on the pitch that issue would be even worse.

Originally Posted by transomstand

Your problem is not the engine, except for being a bit underpowered. The "problem" is the hull. Every hull wants to take a "set" at planing speed, it will always "seek" it. The best way to change it is, as mentioned, with a doelfin type device, or a major change in balance to the hull.

You cannot force the engine to maintain a transitional rpm, the hull wants to go faster or slower, and the engine cannot overcome that, no matter how powerful. It's like setting your car's idle at 2000 rpm, then try to maintain it on a hilly road, you just can't do it.

This is interesting... I would not add a dolefin as stated previously, but I would be willing to add trim tabs to the very far part of the v's deadrise. This might solve TWO problems: Porpoising with a load, and the speed issue at skiing speed. The trim tabs would be WAY out of the water at full speed as the boat gets way up on the pad and there's probably only 12" or so of boat on the water.

Underpowered? Whew. This boat has a USCG rating of 125 - 125 CRANKSHAFT H.P., mind you. When I'm set up for speed this will do 72.6 on GPS, and wow is this little 17' pad-v boat a handful at that speed, even w/ hydraulic steering! In a boat this size 72 feels more like 92. I used to have an '87 Merc. I6 115 on this boat. It pulled me w/ a 20P High Five (not quite as well as this 150 does w/ a 23P), and it held a steady speed. I did not have problems with it holding a steady speed w/ that engine. Hmmm... Very interesting.

TG

**marquis4606** · 08-20-2010, 08:51 PM

my buddy had a problem like this and he played around with the engine height i think he lowered it 1 hole lost a little on top but was more stable haulin tubers/skiers

**transomstand** · 08-20-2010, 09:39 PM

Originally Posted by croSSed

This is interesting... I would not add a dolefin as stated previously, but I would be willing to add trim tabs to the very far part of the v's deadrise. This might solve TWO problems: Porpoising with a load, and the speed issue at skiing speed. The trim tabs would be WAY out of the water at full speed as the boat gets way up on the pad and there's probably only 12" or so of boat on the water.

Underpowered? Whew. This boat has a USCG rating of 125 - 125 CRANKSHAFT H.P., mind you. When I'm set up for speed this will do 72.6 on GPS, and wow is this little 17' pad-v boat a handful at that speed, even w/ hydraulic steering! In a boat this size 72 feels more like 92. I used to have an '87 Merc. I6 115 on this boat. It pulled me w/ a 20P High Five (not quite as well as this 150 does w/ a 23P), and it held a steady speed. I did not have problems with it holding a steady speed w/ that engine. Hmmm... Very interesting.

TG

Your experience with the engine change proves it, you changed the dynamics of the hull by adding 60 pounds to the back. Now it needs to go faster to stay on plane, your plowing a bigger chunk of water with the stern, you need to go faster to get over the "hump", or it will just fall back off plane.

**fyremanbil** · 08-20-2010, 10:24 PM

I had a friend with the same experience on an 25' inboard party boat...which he also wanted to use as a wake board boat. It had plenty of power and would pull your arms off out of the hole and do about 65mph, but you couldn't hold it at 20. That was right at the transition to planing speed and it would hunt back and forth. A dolefin fixed it, but you could probably do the same thing with trim tabs. BTW, the outboard drag guys use some pretty cool looking afterplanes that are attached to the lower unit. It doesn't have to be the same plastic dolefin used on fishing boats.

**transomstand** · 08-21-2010, 05:49 AM

Originally Posted by fyremanbil

I had a friend with the same experience on an 25' inboard party boat...which he also wanted to use as a wake board boat. It had plenty of power and would pull your arms off out of the hole and do about 65mph, but you couldn't hold it at 20. That was right at the transition to planing speed and it would hunt back and forth. A dolefin fixed it, but you could probably do the same thing with trim tabs. BTW, the outboard drag guys use some pretty cool looking afterplanes that are attached to the lower unit. It doesn't have to be the same plastic dolefin used on fishing boats.

Trim tabs would be fine, as long as they can stay wet at the desired speed, and there are aluminum ones that look much less cheesy than the doelfin.

Find the guy who bought Wizard's V-king, should be a free set of tabs in his trash can