Slow holeshot on a 96 xp

[brad]

I have a 96xp with a worx performance kit on it. I have recently been getting poor performance in the the low end. The motor seems to rev to the proper rpms, it just seems as if the prop is just not keeping up. For about 20 feet you go pretty slow, then when the prop catches it finally takes off progressivley. It acts kind of like there is seaweed in the prop. I have flipped the ski over and instpected the intake area. There is no obstruction there. I am not sure where I should start to diagnose this problem.

[Bryan Glynn]

See our article here to inspect your pump.

[kswaterbug]

What exactly is installed on your boat (Worx performance kit). I.E water injection, pipe, different prop, head, etc....

[brad]

A worx handling kit includes 2 high performance sponsons and an intake grate.

[kswaterbug]

Start with checking all the tolerances mentioned in the first response! Next, if this doesn't solve the problem you might have a combination of problems. First things first, Keep it simple. Start with the intake grate might be to progressive for your application. Have you tried reinstalling the stock application? Does this eliminate the problem? Maybe the new sponsons are set to aggressive, causing the boat to cavitate during initial acceleration. Has your new pump shoe been installed filling in all the voids with Marine grade RTV? Sometimes this can cause slight cavitation due to air being trapped here. Try some of these only if Bryan Glynns are unsucessfull in locating your problem. [img]smile.gif[/img]

[spx-performance]

do you have a stock prop or aftermarket? you may need a stepper pitched prop for low end power.the prop you have may be damaged.

[brad]

From what I understand the prop is stock. I am the second owner and I am pretty sure the original owner did not change props. How does a prop just "go bad". To help diagnose the problem, I should add that the lake I use the ski on has a lot of weeds. These weeds constantly get caught up in the intake grate, and I have to jump off to pull them out b/c the ski will not go anywhere. This may have some how ruined the prop.

[Bill O'Neal]

Funny,
I had a GTX come into the shop yesterday and the owner said it does what yours does.

It is called cavitation. The engine rev normally but the boat doesn't go like it should.

The reasons can vary from a poorly sealed pump, or support plate, or intake shoe, to a bent blade on the prop or a bad wear ring. Even a bad driveshaft seal up by the pto can cause cavitation if air is being sucked down the driveshaft.

I aksed him if he had sucked up a ski rope or something. He said no.

I pulled his pump and found no damages, but the ladies swimsuit that was stuck in the pump may have caused the problem [img]smile.gif[/img]

[brad]

Ok, I pulled the pump off and this is what I found. First I found there was play in the prop when I removed the pump. Second when I went to remove the prop off of the screw it was only hand tight.(I think that was the main problem) Third the prop has a few minor dings on it. My question now is, is there supposed to be any play in the prop? And is it possible to have the prop touched up a little while it is out of the ski?

Thanks for all the help.
Brad

[Bryan Glynn]

Send your prop to Dave at www.impros.com - he can fix it for around $80.

No there isn't supposed to be any kind of play - what kind of play do you have?

It was probably loose on there because debris, such as a rock, went through and got cought - it's self-tightening, and the only way it can come loose if from debris stopping it suddenly.

[brad]

I did suck a ski rope up in there! But I backed it out. This problem started occuring before the ski rope was sucked up. That is why I didnt say anything about the rope.

[Bill O'Neal]

If your prop has end play, back and forth, it is NORMAL. Without the cone in place it should move about a quarter inch, with the cone in place it should move between .020 and .040, back and forth (not up and down). The loose prop is not normal, but would not cause cavitation, as the prop tightens onto the shaft as the motor turns when the prop is in the water. Normally they are very tight on the prop shaft. Always make sure you have a few thousandsth prop end play before re-installing your pump with the cone installed. If you have no endplay, you have pinched the flat bearing and will need to replace it or terminal damage will occur to the pump housing. This is a very big and common mistake to make and will cost you plenty if you do not fix it properly before running the ski.

Check your wear ring for major grooves and excessive clearances. Over .025 clearance, and now is a good time to replace it. The absolute limit is .040, but I find over .025 to be excessive.

The older SD pumps need to be "glued" to the support plate with a big bead of silicone all around the diameter of the sealing surface where the wear ring meets the support plate. It needs to setup for 24 hours before riding. A 1996 SD pump uses a newer style wear ring with a built-in seal on the mating surface. You need a neoprene seal stuck to the pump support plate on the '96 model. They cost a couple of dollars each at SD parts departments and make removing pumps very easy.

In general,
Props can be touched up with a hand file, but only if the damage is very minor and no blades are bent. If you have an aluminum prop in a early model SD, get a stainless steel prop to replace it.

[brad]

I checked the wear ring to the prop. The gap is .025 - .035. I used a combination of .010 and .025 shim stock to check. If there is more than a .o25 gap cant that also mean the prop could be bent rather than the wear ring wore? Also what is the gap between the ring and the prop when both are brand new? Lastly do you think I should try buying a new wear ring for a start. One more question, could my sponsons being set to low be a cause for cavitation? Sorry for all of the questions. Thanks for all of the answers.

[Bryan Glynn]

Sponsons have zero to do with cavitation.

If you are at 0.035" you are right near the absolute limit and I would be expecting bad cavitation, yes. The clearance when new depends on the components. My aftermarket impellers have FAR less clearance than my stock one did. I would make sure your prop is in perfect condition, and if so get a new wear ring.

[Bill O'Neal]

The clearance is very little with new components, and may even rub in a spot or two, which is ok as long as you can still turn the prop. It will clearance itself if it drags a bit.

By all means, replace that wear ring while you are in there. .035 is excessive wear.