I have a stock 1995 Kawasaki JS750 SX Jet Ski. It performs flawlessly and currently there is nothing wrong with this boat.
I am toying with replacing the OEM impeller with an aftermarket Kawasaki performance impeller. I have purchased a service manual. Should I notice a performance improvement with an aftermarket Kawasaki Impeller? Given that I am more mechanically inclined then average, is this a impeller removal job I should be undertaking myself, or should I seek professional mechanic assistance? I heard that it could be quite difficult removing the oem impeller from the jet pump impeller shaft. If I do this impeller job myself, should I expect the need to replace any pump bearings, pump seals, ect?
Changing your original impeller to an aftermarket Kawasaki performance prop will help, but you also should check the jet pump housing and make sure it is in good shape and not worn out.
As for changing the jet ski impeller yourself, If you have more then average mechanical ability and think you can handle it, Then just do it ( but make sure you have impeller removal tool).. If you ride in fresh water it should be no problem to get impeller off shaft. If you ride in salt water sometime the salt water impellers are a little more difficult and You might have to add some heat to impeller. I would recommend changing your pump seals & bearings with a Jet pump rebuild kit since ski has been in use for many years. Follow your repair manual and You should be fine.
Ski Maintenance Pro
I own a stock 89 Kawasaki 650 SX Jet Ski, except for a stainless SOLAS impeller. I usually ride on the rivers and lakes in Virginia. Every now and then, I get to do a little ocean riding at Virginia Beach. Im looking to squeeze a few more hoursepower out of my Jet Ski. Im hoping you can help. I noticed you frequently recommend air filters for better flow. I took a look around and there are many sizes, shapes and designs to choose from. Also will advancing the timing help my performance? And Should I mill my head?
The best performance you can do is add a performance exhaust system. It will improve performance all through out the power band.
For timing your ski is fitted with an adjustable stator plate assembly. The timing can be changed (advanced) simply by rotating the stator plate assembly counter clockwise. Be careful not to advance your ignition timing to much from factory setting . Only 3-4 more degrees are needed to help improve low-speed response.
You can safely cut your OEM head to get more compression. I recommend Removing .070 (seventy thousands) from the surface, then open up/machine the squish band area to your exact bore size. be sure to keep stock chamber angle too. This will give you approximately 170-175 cranking compression. You will still be able to run pump gas 92.
After market flame arrestor filters are all pretty equal. The main point it to improve flow.
I think I need more low end torq. Im a smaller rider, weighing in at only a 150lbs. I ride a 1994 Yamaha SuperJet 650. I love performing various tricks & freestyle on it and I'm getting to the point where more low-end kick will really help me out. With all this impeller pitching and Yamaha impeller choices, its hard to figure out what would be best for me. Which can you recommend for my type of jet ski riding? Thanks in advance.
You only need a 175-180 psi head. You can have your head machine or buy an aftermarket head. Flame arrestors will help letting engine breath better and remove the choke plates and install a primer kit for better flow.
Impellers, if your looking to just replace the OEM set up for now, Go with a Solas I or PRO. They give excellent better low end acceleration and even a little more at top.
I have a 2002 Sea-Doo GTX DI, It ran perfectly, and then I winterized it, and, after taking it out of storage, it lost approximately 5 mph. The engine only gets to 4000 rpm until its been run across the lake, then it loosens up and reaches 5500rpm. weird. Do you have any ideas? Do the exhaust ports need to be cleaned every so often?
Sea-Doo recommends annual cleaning of the RAVE valve guillotine to remove carbon build up. But a bad water regulator valve, low fuel pressure or a jet-pump problem can also cause this problem.
My 1999 Sea Doo GTX RFI has approximately 100 hours on its powerplant. The problem is that on initial acceleration, either while I'm alone or when pulling a wakeboarder, the machine does not have smooth, crisp transition through the powerband. on take off, it appears to be labored acceleration. However, when the machine begins to plane, everybody is happy. Is there an easy fix for this?
The GTX RFI has a Rotax Adjustable Variable Exhaust (RAVE) system. If the RAVE valve gets stuck open, you can experience a rough take off Sea Doo recommends annual cleaning to remove carbon, However, other things, like clogged injectors and the need for TPS adjustment, can also cause the problem you described.
I have a question about CDK II carbs, I have found little performance info on these aftermarket carbs. I want to upgrade the carbs on my Ultra 150, but i dont want to spend a ton of money and have to change the fuel system on my ski. The changes have to be done with the 48-50 style carbs. I have a few mods done to the jetski , and I feel it is time to upgrade the ski. I have a Billet head 165psi, Inland Jet exhaust mod, flame arrestor, Solas DynaFly 16-20 impeller, Shredmaster ride plate, Solas Intake grate and Aggresser Sponsons.
The Mikuni 48mm Blackjack carbs with Inland Jet Manifold works great on the Ultra 150. I would also recommend V-Force Reed valves for extra rpm. Plus, a set of 1.5 inch air filters. Its not cheap but You will rule your local lakes....
Jet Tech Pro
I'm wondering if you can help me with winterizing my ski. I have heard to put fuel stabilizer in a full tank, partly full ect. Also make sure no water in system and put a bit of motor oil in each spark plug hole. Kind of a variety of efforts, and I'm wondering if you could help me in the correct way to winterize my jet ski?
Hi Henry, When winterizing a ski, I put fuel stabilizer in a full tank of fuel and run the motor to make sure that the fuel stabilizer gets into the fuel system completely. Then while ski is running, pour antifreeze into cooling system until it comes out at the exhaust, then squirt fogging oil into the carburetor until the motor stalls. This whole operation should take about 30 minutes with no water hooked up. Then you remove the spark plugs and poor about an ounce of motor oil in each cylinder and turn the motor over to make sure that the oil coats fully. Then you should check the pump for water under the cap and re-seal the pump if it has been exposed to water. Then you should lubricate all fittings and moving parts (steer, trim ect..)
Hi Tech, I own a 1994 Kawasaki 750Xi jet ski and its a great ski; however, I am looking for more power and speed. Ive talked to a local dealer about hop ups, but no dealer was really giving mean answer.
Im looking for a bolt-on kit. No major engine modifications (i.e. pistons, cranks, ect.). Some kind of package that will give me a good 4-6 mph increase in top speed and a real punch in acceleration. I was thinking of milling the head, How much psi for pump gas 92 fuel? An exhaust system what kind, brand? An impeller-what pitch? and what other modification must I make to retain proper operation and reliability (i.e. carburetor, ect)
Get a after market performance head 180 lb or have a machine shop mill your head .030 inch's, while retaining a .050-inch squishband clearance. This should bring your compression up to about 180-185 psi. Pump gas octane fuel will be fine. I suggest you change from your stock flame arrestor to an aftermarket air filter so the engine will breath easier. A factory pipe exhaust pipe works well on the Kawasaki 750. You can use the ski's stock water box. You will have to richin your carbs per factory pipes recommendations. Install a performance impeller.
The problem I am having is free reving. At least that is what Im told its called. My 94 Blaster is mostly modified to a "limited". OK, this is where Im getting confused, four different people told me four different possible solutions. One guy told me that a piston ring was stuck, so just richen the carb and go for it. The second guy said that I may have a bad crank seal. The third told me I had a bad CDI unit. The last guy said that the crank/flywheel keyway was sheared off. So who has the right answer? Is there a way for me to check myself?
The second guy is the one with the correct answer. I assume your free revving occurs when your Blaster is out of the water. There for an air leak of some kind is evident. You need to take care of this right away. Severe air leaks cause a lean condition, throughout the engine. This problem will lead to a top-end seizure. You need to have a mechanic do a pressure test on your engine. You can also look in the flywheel cover for oil seal leakage. If it is leaking you need to get a seal kit.
Hi Guys, I own a stock 1996 Sea-Doo XP with the 782cc RAVE motor. Although this machine is an excellent all-around performer, I have the speed itch and am always looking for the performance edge. The modifications I seem to hear discussed the most are Seadoo performance impeller, flame arresters, mill head or aftermarket head, and re-jet the carbs. What would you recommend?
The performance mods you mention are good starting point . First, change your Sea Doo flame arrestor and replace your choke with a primer kit. The next step is to have your watercraft's head milled or buy billet head.
A variable pitch impeller will help with acceleration and top speed. Also a intake grate will help with rough water riding.
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