96 sportster capabilities?

[larrybr45]

I am new to boating as of yesterday with a 96 sportster. Seemed well maintained, he has a rebuilt engine in 2009, stainless impeller etc., seats new. He got rid of an injector for oil and has it setup for premix amsoil and then there is a container he put in too that is just amsoil.

My question is, we had 3 adults and 2 kids and it took awhile but went to "high speed".

We then went down to 2 adults and 1 kid. It was tough getting to get engine to wind into high speed, even with throttle all the way full. Seems that it would finally kick in. We had more luck when I would turn boat a little then it would kick into high speed.

We then took child and put on a tube. We could not really get going fast at all, the engine never really got to the high rpm level.

Any suggestions, am I doing something wrong? I am worried I got suckered into something.

thx

 

[Dr Honda]

If the engine is not reving up... you have serious fuel issues, and need to fix them before you roast your engine.

BUT....

I think what you have is cavitation, and your engine is reving up to it's limit, and bouncing off the rev-limiter. So... are the RPM's coming up, and sounds like the engine is bouncing, or cutting out?

 

[larrybr45]

I dont know all the technical terms, but it seems I need to start slow and the front of the boat lifts up and then all of a sudden it is like the boat hits high gear (even though i did not move the throttle) and we go sailing across the water very fast.

I was never able to get this speed towing a tube though. And one time we had to go around a lake lagoon a couple times before it kicked in high speed with 3 adults and 2 kids.

I am worried I have huge problems now.

 

[RFoster130]

Sounds like you are just experiencing cavitation. It is normal with these boats. The boat is propelled by water being thrusted out the back through a nozzle. To get maximum thrust, the tolerance between the impeller and the wear ring around it must be very small. As things get sucked through the pump, they cause the wear ring to get damaged. The ring then has a bigger gap between it and the impeller. When you put the boat under a load, it loses thrust and you dont move as fast as you should. This problem is multiplied like 10x when you increase the load in the boat. Dont overlook the fact that you have the boat severely weighed down. That boat is rated for 650 lbs or 4 people. Sounds like you are probably very close to that or over.

I bet if you take the boat out by yourself, you notice a difference. The good news is that it is usually a simple fix you can do yourself for about $100. Everything you need is here.

Some tips for ya.....When you are taking off the front of the boat will lift high up. The boat is trying to get going enough that it levels out. That is called getting on plane. Once up on a flat plane, it will be a lot easier to maneuver. That is where you need the boat to be. Usually it takes a lot more throttle to get the boat up to plane. Once there, you can back off the throttle. If you go out and practice you will learn the point to where you can back the throttle down and still keep the boat planed out. If you slow down too much, you basically start all over again. Only way to learn it, is to get out and practice a lot. The weight in the boat makes a big difference though.

Read up here on things like cavitation. Go look inside the intake on your boat and see what the impeller and wear ring look like. I am guessing it needs some work.

Also....dont overlook safety. Like i said, that boat is rated for 650 lbs or 4 people. Dont go over that. Not only is it illegal, it is dangerous....especially with kids.

 

[larrybr45]

Is there a ballpark idea what a dealer/mechanic might charge to fully fix the cavitation? Beyond changing oils, sparkplugs I am not much of a mechanic.

 

[RFoster130]

Depends on what the problem is and how honest the mechanic is. If it is something as simple as a wear ring and they dont try to hose you...i would guess $300. If it is something else, it could cost a lot more. That is why it is best if you just read up here and listen to people that have been in your shoes. Changing the wear ring is very simple and can be done in a about an hour with minimal tools. There is an entire thread on how to do it. You need to find the problem first. Look inside the intake...it may be very obvious, or take the boat out by yourself and see how it handles with less weight in it. Give it full throttle from a dead stop...see if it revs up before it moves. See what your max rpm's are. Once we diagnose the problem, we can get you fixed up. Another reason to do it yourself is most shops are backed up for weeks this time of year.

 

[larrybr45]

Thanks for taking the time, I will get back in it mid week. Just so I am clear, push throttle all the way up (max) and see if it fires to max engine speed? I have no tachometer on my version.

Also, can any of the repairs and looking at intake be done with the boat in the water?

thx

 

[RFoster130]

To properly look at it, you need it out of the water. When you do have it on the water, from a stop push it to full throttle. Does the engine rev all he way up and you are just sitting still like a slipping clutch or transmission in a car?