XR2 Help for more power

[1quickET]

Ok i have a 1987 XR2 150hp on a 16ft carlson the boat has a 19pitch quicksliver prop and runs about 6000RPM at wot. The boat will only run about 50mph acouding the speado on the boat. What can i do to get a little more preformance from it. Motor is all stock. I removed the oli injection and left the punp and gear in place. Should i remove the gear from the oil pump? Also below 3000rpm the motor runs rough and has no power. Dont know **** about boats but posted on yellowbullet and said you guys were the people to talk with. Thanx for the help. Also compression on the motor is 115-120

[Sonik]

Welcome to S&F!! First and foremost, you need to remove that pump and replace it with the appropriate blockoff plate...sorry I don't have the part # in front of me at work. This plate supports/retains the inner bushing and keeps it from making a mess of the rotating assembly if it were to fall out. I suppose the first things you want to ensure involves motor health....which apparently is an issue with a rough midrange. Your problem could lie in quite a few places.....fuel pump, carbs, stator, switchboxes...etc. Did the motor sit for extended periods of time without use?? Was it properly stored over winters??? Have the carbs or fuel pump ever been gone through??? At what height is your propshaft in relation to the bottom of the boat??? Are you running a jackplate or is the motor bolted to the transom??? The best $ I ever spent was buying a Mercury Service Manual when I knew nothing and now I know just enough to be dangerous!! :thumbsup:

The manual will give you test procedures on ignition and fuel system components that will get you pointed in the right direction. The motor will turn 6k rpm so you may have a low speed stator starting to dump on you. We need more info about your setup and history of the motor to really be of any good help. There are quite a few factors that may contribute to your problem.

I think once you solve your runability issue, that motor will do everything you really want it to do on that hull. I assume your carlson is a round bottom (no pad) and things can get interesting in those hulls over 60-65mph. Seeing speeds in the high 60's with that motor isn't unreasonable given the motor is healthy and the boat is set up properly. :cheers:

Jeff

[1quickET]

I know i brought this to the right place. Some history I just purchased the boat about 4weeks agow. I have no idea about how it was stored but it didnot sit for long a long time. It was at the lake all this year. The carbs and pump prob have never had any work done to them. Info from the seler the motor has very little time on it. The motor has no jack plate and motor is all the way down on the transom.

So i need to measure from the bottom of the boat to the shaft? I will get on that. What height would be good?

Also where would i go to look for a oil pump block off plate.

Another question is about an above water exhaust is it worth it. Seen a boat on the lake with two holes drilled in the mid section and it sounded sweet. Is there any tech on how to do this?

And last question i was going try a prop from a frends XR6 buth the ODs of round part of the prop were different. My prop has a larger section on the foot that the prop from the XR6 what is up with that?

[Sonik]

I know i brought this to the right place. Some history I just purchased the boat about 4weeks agow. I have no idea about how it was stored but it didnot sit for long a long time. It was at the lake all this year. The carbs and pump prob have never had any work done to them. Info from the seler the motor has very little time on it. The motor has no jack plate and motor is all the way down on the transom.

I would start with the standard "check everything" over. "Very little time" doesn't necessarily equate to "in good shape" as we all know. Look for fuel leaks, frayed, torn, or rotted hoses, wires, or bleed lines. Spend the $10 and buy a fuel pump kit for it...it takes 10 minutes to throw a set of gaskets and diaphragm in it....cheap insurance....trust me...I just found this out. Check your fuel lines, quick disconnect if you have it, and squeeze bulb for servicability. Check all the lines leaving the fuel pump to the carbs. Ethanol plays havoc on older stuff and the inner lining deteriorates then flakes off and is carried down stream to clog filters, screens, carb seats, low speed circuits, etc etc.


So i need to measure from the bottom of the boat to the shaft? I will get on that. What height would be good?

With no jackplate you obviously are limited to the adjustment in the clamp assembly. Assuming you have side water pickups, you're still limited to a propshaft height of 2-3" below the bottom of the boat. A water pressure gauge is an invaluable tool when doing setup work with motor height becuase it will tell you your limit. I can't imagine that you will have a water pressure problem running the motor higher on the transom BUT, get a gauge, get a gauge, get a gauge!! :D Every little bit you raise the motor has an effect on how the boat runs and handles. One way, (level boat and propshaft) is to just use a 4 or 6ft straightedge along the bottom of the boat and use a tape to measure the vertical distance between the straightedge and propshaft center..... Another is to level the boat/trailer on a hard surface like a concrete garage floor and measure from boat bottom to ground, then propshaft to ground and since your propshaft is below the bottom....... (boat to ground in inches) - (propshaft to ground in inches) = propshaft height below pad/bottom of boat.


Also where would i go to look for a oil pump block off plate.

You need Part # 43453 - oil injection blockoff plate
Part # 43454 - o-ring for blockoff plate
Part # 43455 - bolt for plate qty 2

As to where, any mercury service facility or marina should be able to get you those parts but you'd get a better deal dealing with vendors here on our website.



Another question is about an above water exhaust is it worth it. Seen a boat on the lake with two holes drilled in the mid section and it sounded sweet. Is there any tech on how to do this?

Drilling on the back or rear of a fishing type midsection will get all kinds of people fired up and start some controversy. Reasoning behind this is that the rear of midsection is a high stress area and removing material can be a bad idea so it is said. An acceptable practice is drilling 4-5 vertical holes directly above the cavitation plate on each side in the midesection ( must be done fro mthe inside) but this requires the removal of the powerhead and exhaust liner inside the mid to accomplish anything. the other option is to buy an offshore midsection which will most certainly satisfy your need for noise....and subsequent DNR tickets early in the morning. :thumbsup:


And last question i was going try a prop from a frends XR6 buth the ODs of round part of the prop were different. My prop has a larger section on the foot that the prop from the XR6 what is up with that?

The XR6 gearcase has a smaller bullet diameter than the XR4's and XR2's. As long as you both have the small propshaft (15 spline) in that XR6 case his prop will work. It will be like running an over/through hub prop....some exhaust will exit over the blades and allow it to slip when coming out of the hole....which is a benefit in some cases....no biggie....just make sure you use the correct thrust washer behind it.

[1quickET]

Ok i did some measuring on the boat. From the bottom of the boat to the center of the prop shaft is 10in. I can move it up 3in from the holes on the motor. Would it be worth it to get a jack plate to move the engine up 7-8in? And what is the best jack plate for the money?

[croSSed]

A jack plate was the single most beneficial thing I did for improving the top speed performance from my XR2 powered Cee Bee Avenger Mach II. You have to play with it some, but with my motor jacked as high as it will go before the water pump starts sucking air, I'm getting 72.6 mph on gps, running a small hub Laser II w/ blow out ring (26p) turning 6300 rpms. BTW, the extra set back of the jack plate improved overall performance. When I put my 23P High Five on, drop the engine down (it is still a lot higher than having bolted to transom), I have better out-of-the-hole performance, and better handling than I did w/o the jack plate. With the High 5 on there my boat performs like a Corvette on water: BEASTLY acceleration, tight handling, but... I lose the top end performance. Still, it is more fun to drive with the High 5 because of the way it handles/accelerates!

TG

[90 5.0]

A jack plate was the single most beneficial thing I did for improving the top speed performance from my XR2 powered Cee Bee Avenger Mach II. You have to play with it some, but with my motor jacked as high as it will go before the water pump starts sucking air, I'm getting 72.6 mph on gps, running a small hub Laser II w/ blow out ring (26p) turning 6300 rpms. BTW, the extra set back of the jack plate improved overall performance. When I put my 23P High Five on, drop the engine down (it is still a lot higher than having bolted to transom), I have better out-of-the-hole performance, and better handling than I did w/o the jack plate. With the High 5 on there my boat performs like a Corvette on water: BEASTLY acceleration, tight handling, but... I lose the top end performance. Still, it is more fun to drive with the High 5 because of the way it handles/accelerates!

TG


interesting, i'm having a ton of problems with my 23p high five blowing out in turns and blowing out with throttle /trim..

see this thread...


http://www.screamandfly.com/showthread.php?220269-Talk-to-me-about-this-prop-Mercury-High-five.



also, to the op, the xr2 is a great little motor, i used to have one. i don't know the weight of your hull but when you get it running right it should scoot, i'm guessing you should be able to turn a 23-4 pitch prop like the trophy when you get it tuned up and a j-plate thrown on there...

[90 5.0]

A jack plate was the single most beneficial thing I did for improving the top speed performance from my XR2 powered Cee Bee Avenger Mach II. You have to play with it some, but with my motor jacked as high as it will go before the water pump starts sucking air, I'm getting 72.6 mph on gps, running a small hub Laser II w/ blow out ring (26p) turning 6300 rpms. BTW, the extra set back of the jack plate improved overall performance. When I put my 23P High Five on, drop the engine down (it is still a lot higher than having bolted to transom), I have better out-of-the-hole performance, and better handling than I did w/o the jack plate. With the High 5 on there my boat performs like a Corvette on water: BEASTLY acceleration, tight handling, but... I lose the top end performance. Still, it is more fun to drive with the High 5 because of the way it handles/accelerates!

TG


interesting, i'm having a ton of problems with my 23p high five blowing out in turns and blowing out with throttle /trim..

see this thread...


http://www.screamandfly.com/showthread.php?220269-Talk-to-me-about-this-prop-Mercury-High-five.



also, to the op, the xr2 is a great little motor, i used to have one. i don't know the weight of your hull but when you get it running right it should scoot, i'm guessing you should be able to turn a 23-4 pitch prop like the trophy when you get it tuned up and a j-plate thrown on there...

[1quickET]

Ok got me a jack plate on the boat the prop shaft is sitting about 2-3in below the bottom of the boat. Now my question is what am i to do with my steering. The cable in the setup will not reach the rudder on my motro. Is this a good setup? If so can i just extend the rudder arm out and connect back up?