On my '03 GTX SC, I just replaced the pump (aluminum pump housing, new wear ring, bearings). I also replaced the impeller with the Solas recommended one for stock engines (Concord SR-CD 12/20). I also replaced the driveshaft, thru-hull floating hat, carbon seal, PTO bearing and bellow. The oil and filter is new (10w-40). The spark plugs are new and are the recommended plugs. The supercharger was just professionally rebuilt too. All the hose clamps were replaced with new stainless ones and they are all tight. My ride plate and intake grate are stock and the bolt holes are not filled. OPAS is not blocked up yet. Acceleration feels good, but the problem is...I just took the ski out today for the first time and it will only hit about 7,050 RPM and about 61 MPH on the speedometer, which we all know is really only about 56-57 MPH on GPS. It was 80 degrees outside running in nearly flat salt water with no real current in a cove area. Why are my RPM's so low? From what I read on here 7650 is the rev limit and the sea doo service manual says RPM's should be 7300+/- 50 RPM. There are no sc leaks at the connections, there is no water in the hull and the oil looks fine with no water in it. Any ideas?
'03 GTX SC 185hp - Low RPM problem...need answers.
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If nothing else., swap the impeller back to the OEM impeller. You did so many things that it is hard to start somewhere. By swapping the impeller it may give you an instant answer.
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mkov608
Active Member
Funny! I was just chatting with Ski-doo on the message side about a similar problem. I have identical skis, and I serviced both jet pumps (along with everything else) last Nov; I used all OEM parts, and the impellers look good. I took the skis out last week, and one runs right about where yours does ... 7K RPM. The other runs at 7.3K RPM. The difference is noticeable! Ski-doo suggested swapping the jet pumps to see if the problem moves. Looks like a project for this weekend. The more I think about it, the more I wonder if the original owner changed the impeller; the slower ski has always run slower.
Coastiejoe...Unfortunately, the old prop was chewed all up along with the pump and wear ring due to the previous owner sucking up a rock. The stock impeller was toast and cannot be re-installed to test it. The Solas prop I installed is the one Solas recommends for a stock 2003 GTX SC (185HP) engine. It is supposed to increase performance slightly not lower it. Also, I just bought this ski recently with the bad pump and impeller so those things had to be changed before my first use. The rest of the driveline was replaced after one ride because I had 4" of water in the hull do to a broken clamp on an exhaust water line. This revealed a bad PTO seal bearing that allowed water to enter the engine oil. I have changed the oil 6 times to flush the water out and put the all new driveline in from the PTO seal to the pump assembly. Everything on the engine and hull is water tight now and the oil is honey colored. I haven't done a final oil change to a JASO MA1 or MA2 oil for SC engines. I currently have regular Valvoline 10W-40 in the engine and it was full to the top notch. I changed the plugs too. The engine runs nice and smooth and the supercharger is definitely working. Could the oil being at the top notch and the fact that it is not the right oil for a wet-clutch application cause the engine to lose some RPM's? I can live with the speed where it is, but I would like for the ski to at be able to go as fast as it should. Any more ideas? mkov608...let me know if you get an answer from ski-doo to your question regarding your slower ski.
One thing the 4-tec engines hate is having the engine oil over-full. It MUST be between the marks. If to high it puts pressure in the crank case and you WILL lose performance.
When it comes to impellers, generally speaking, any impeller that will give you increased low end performance will decrease the top end speed. And,, any that give a better top speed often give a decreased lower end performance. So,, this could be your issue. If you have notice a great out of the hole performance and better low end responsivness, it may be as simple as having a different impeller..
When it comes to impellers, generally speaking, any impeller that will give you increased low end performance will decrease the top end speed. And,, any that give a better top speed often give a decreased lower end performance. So,, this could be your issue. If you have notice a great out of the hole performance and better low end responsivness, it may be as simple as having a different impeller..
Thanks Coastiejoe. I will do another oil/filter change with the proper type of oil and make sure the level is between the marks and hopefully that will help get me another 100 RPM or maybe more. We shall see. The out of the hole performance is really good so yeah, I might have to sacrifice a little top end, which is ok with me because I like to play around and do 360's and jump waves more than going WOT.
mkov608
Active Member
Well said! When I moved from Phoenix to Utah, I put a high altitude impeller on my '95 XP since the higher altitude will decrease engine output. I also put a stage 1 performance kit on the engine. I did notice a decrease in top end, but the ski would jump right out of your hands if you weren't holding on tightly! However, my max engine RPM didn't change.
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