'06 GTX SC tops at 55 mph

[zonzik]

Hello, everybody! Recently purchased 2006 Sea-Doo GTX Supercharged 185HP Jet Ski. It has only 36 hours on it. There were some parts missing, like the jet pump housing. I purchased everything and put it back together. The jet ski runs just fine but the top speed I was able to get was 50mph at 6800rpm. 1 person, 2 persons it didn't matter-50mph. I took it to the dealer to check what might be wrong. They tested the supercharger and inspected the pump. Was told that everything is fine. The oil level was 1 quart low (i changed it the day before) and lots of codes showing on their computer (which is probably normal because all the harnesses were disconnected when i bought it). They cleared them and when tested on the stand there were no more faulty codes. Next day I tested it on the lake and it got to 55-56mph at 7100-7200rpm. From what I found on the web it should go 60-65mph. at around 7500rpm. I should say that I put brand new jet pump housing but the impeller is old and not in perfect condition. Any help will be much appreciated. Thank you!

 

[lamajama]

I think 60 is around top end but it depends on so much else too....amount of fuel (weight), rider (weight), water conditions as well as impeller etc. I've flirted with 61 on an 04 SC 185. Your gauge could very well be off too. My previous 02 GTX DI speedo was about 8 mph low. Didn't bother to change it out..I'd be happy if all running good. After all at WOT you're going thru a tank of gas in about an hour....!

 

[lamajama]

BTW my 04 runs 91 octane. Your's might require that too and that would help.

 

[zonzik]

Thanks for the reply! Yes, I use 91 and added some injector cleaner as well. The gas tank was full but still I was expecting little more from it. I used to have Sea-Doo Speedster jet boat 170HP and it was doing 60mph. This one is a lot lighter and with 185HP... I just want to make sure it's normal and nothing needs mechanic attention.

 

[Coastiejoe]

To give you some comparisons. My 2010 GTX-155 no SC hits 55 in perfect conditions. My 09 RXZ-X with a SC hit 72 pretty easy. 75 trimmed out properly. In both case 2/3 tank of fuel.


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[zonzik]

So I thought. It should do at least 60-65. Is it possible to be the impeller?

 

[Tytan]

60mph is about the best you will get, I have a stock 05 GTX SC 185hp and I have seen 61mph under the right conditions. This is measured with a Garmin 76 GPS, not sure what the dreamo meter says.

What prop did you install ? If you're only getting 7200rpm then the prop might be too steep.

 

[zonzik]

The prop was really old and not in very good shape. The guy who sold it to me said that it needs to be rebuilt but "will do the job for now". I guess that's what it's doing...
So it is possible to be a bad prop? Tytan, what RPM do you get at 60mph?

 

[Tytan]

I'm at 7500rpm. The impeller, wear ring and pump veins have to be perfect if you want max speed. If the leading edges of the impeller are rough, one blade is slightly bent, wear ring is grooved or stator veins in the pump chewed up or missing, any of these will decrease the mph.

I had an 04 RXP that would GPS at around 74mph with a perfect impeller and wear ring I sucked up a rock and bent the trailing edge of one blade and the max speed went down into the high 60's.

Wait until you winterize then send your impeller to Impros for a clean up it will come back looking and performing like new for a fraction of the price of a new one, reinstall with a new wear ring and you will see a speed increase.

 

[zonzik]

Yes, one of the leading edges is really rough. The wear ring and everything else is new. Is it possible because of the impeller it can't get maximum RPM? Also what's that place Impros that rebuilt impellers? I was going to send it to SBT.

 

[Coastiejoe]

Impeller and wear ring are crucial to speed and performance.

The gap must be under the width of the dime from the impeller to the wear ring. If the impeller is rough, it can easily be the issue. This is especially true if a fin is bent.

 

[Tytan]

Yes, one of the leading edges is really rough. The wear ring and everything else is new. Is it possible because of the impeller it can't get maximum RPM? Also what's that place Impros that rebuilt impellers? I was going to send it to SBT.

Post a pic of the impeller.

Not hitting max RPM could be because of condition or you got an impeller with the wrong pitch.

www.impros.com

SBT probably do the same thing I have no experience with them I have used Impros in the past with good results.

 

[zonzik]

Thank you guys! Will try to rebuilt the impeller and will post the result. Hopefully will have time to test it before the snow hit Wisconsin...

 

[zonzik]

Took it off today. That's what it looks like.

 

[Tytan]

I have seen a lot worse, not the greatest condition if you're after max speed I would get it repaired. If you're OK with the way it runs now I would use it for the rest of the season then send it out for a professional repair over the winter.

You could buy a new one, send that out for repair and keep it for a spare then if you do damage an impeller mid season you have one on the shelf to minimize down time.

 

[zonzik]

Thanks! Do you think it's possible to be the impeller? I already ordered remanufactured one from SBT. They work on exchange basis. Once I receive the new one will have 2 weeks to ship the old one.

 

[red2blue]

Thanks! Do you think it's possible to be the impeller? I already ordered remanufactured one from SBT. They work on exchange basis. Once I receive the new one will have 2 weeks to ship the old one.

If it was me...and in your present situation...which I wouldn't have done....anyway.

I'd try the sbt retread...if it solved you prob...cool...I'd send them your old one. If not...I'd send it right back to them...reinstall my old one...ride the rest of the season and then send it to Dave at Impros.

Pic just loaded....it don't look that bad. ring don't look terrible either. How're you checking your oil level?

 

[zonzik]

Oil level is normal.

 

[red2blue]

I don't mean to be a dck. There is a reason I'm asking.

How exactly are you checking your oil level?

 

[zonzik]

Using the stick. I know if the level is low the engine might go in slow mode. If that's what you mean.

 

[red2blue]

nope....

With the ski level on trailer warm the motor for 30sec...shut off. Count off another 30 sec....oil should be half way between the bends.

In the water...with warmed motor...shut off...30sec check the stick...half way between the bends. You want some of the oil up top of the motor when you check the stick.

If it's over filled...even a lil...you'll lose rpm. I see people over-filling all the time.

Even when all is as it should be...a non ic'd ski will not crack 65...let alone 70...w/o some work. It can be done...don't get me wrong...it just ain't gonna happen straight from the factory.

 

[zonzik]

When it's cold it's maybe a little bit over the MAX, but that's how they filled it at the Sea-Doo dealership...:banghead:

 

[TplusR]

When it's cold it's maybe a little bit over the MAX, but that's how they filled it at the Sea-Doo dealership...:banghead:

I had this issue at the beginning of the season when I overfilled one of my skis. I removed a little oil to get down to the correct level and performance returned to normal. red2blue knows his stuff :thumbsup:

 

[ski-d00]

half way up the dipstick is where it should be. as soon as it gets to full or just a little over full on the dipstick you will start to lose performance. very sensitive to high oil level. most dealers are clueless.

in your pic of the impeller, you didn't show the trailing edge which is the biggest factor in top speed. a chewed up trailing edge will greatly affect top speed. a chewed up leading edge can affect take off and acceleration.

are you sure that is even the correct impeller for your ski? you should hit 7500 rpms, rev limiter is at 7650 for the 185.

your top speed will be 60 if everything is right. never will it get close to 65. maybe 61-62 on a good day with empty tank and a light rider. the 155 and 185 basically have the same top speed of 60 but the 185 will pull a little harder.

 

[zonzik]

I couldn't take picture on the other side because it's still mounted on the housing. I should get the removal tool and the new impeller this week and will post updates.