Seizure occurs when the piston expands and sticks to the cylinder, stopping the engine. Lack of lubrication, a major reason for PWC engine seizure, occurs when fuel and oil are mixed in the wrong ratio, or your oil runs dry. Problems can also be caused by using cheap or non-recommended oils that do not have lubricating qualities required by PWC engines, Failures of oil injection systems are very rare. Over heating is probably the most common cause of seizures. Other possible reasons for seizures are improper tuning of the carburetor; Advanced ignition timing; lack of cooling water; air leaks (causing lean mixtures) at the carburetor or intake manifold, head or cylinder gaskets, or crankshaft seals.
The way to prevent seizures is to have your carburetor adjusted properly by a professional mechanic then leave it alone, use good oil, and make sure your water cooling system is working. (keep an eye on the bypass-water should always be flowing when the engine is running). Tech Talk
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Making adjustments to the Jetski carburetor air/fuel mix is pretty easy. nearly all watercraft carburetors are fitted with high speed (30-100 percent throttle) and low speed 90-30 percent throttle fuel mix adjustment screws. In a stock application the screw closest to the mounting plate of the carb is always the low speed screw; The one nearest the air intake is the high speed adjuster. turning them out (from bottom closed position) will richin the fuel mix. Pop Off PressureThe relationship between pop-off pressure and low speed jets. " those two circuits overlap" although the low-speed jet continues past 1/4 throttle engine operation, whereas pop-off pressure has little to no effect due to increasing air velocity in the carb. also, one can make up for slight inadequacies in the other. "For example, if your pop-off pressure is a bit high, you can compensate by increasing the size of the low speed jet, The opposite is true, too: a slightly undersized low speed jet can be compensated for by using less pop-off pressure." When does it become necessary to adjust the pop-off? "Pop-off pressure refers to the pressurization of the needle valve with compressed air, through the fuel inlet," "this is a reference to the amount of pressure needed to open the needle valve-- or 'pop' it off its seat. The higher the pop off the more pressure required. "When personal watercraft or Jetboats come from the factory they have fairly high pop-off, due to the fact that they also have somewhat restrictive air intake systems that cause the engine to generate very high manifold pressures. The higher the manifold pressures, the higher the pop off pressure required to properly regulate fuel delivery to the engine" As you modify or change your flame arresters to a less re-strictive type ( meaning more flow), you are lowering this manifold pressure--- and are inadvertently creating a 'lean' condition in your engine. Changing the pop-off pressure--- which is nothing more then switching the Needle Valve Arm Spring in the regulator to a spring with a softer compression (gram) rating. "sometimes in order to achieve the desired pop-off pressure it's necessary to also change the needle valve size. Just remember its always better to use the smallest needle valve size to obtain the correct pop-off" Tools Use Pop-Off Gage Carb Performance TrickRemove the choke and replace its function with a primer kit. Though most PWC enthusiasts tend to regard the use of a carburetor primer as "band aid" for an ill tempered engine or comp device, it offers benefits for virtually any watercraft.The single biggest limitations to a carburetor operation is airflow; anything you can do to improve the flow (and velocity) of air through the carb will usually result in increased performance. Choke assemblies, which incorporate regulatory devices similar in appearance to throttle plates (but located at the top of the carb) are an obvious impediment to air flow. Basic Mikuni Super BN CalibrationThere have been a number of diffrent carburetors used to for feeding PWC over the years, primarily by mikuni, with the end result being the popular mikuni super BN carb. It is designed specificaly for watercraft -- meaning it is essentially a sealed unit that canot vent its fuel chamber to the atmosphere (which would allow fuel to leak into the hull in rollover situations).
Though accurately tuning this (or any) carb for your application is limited by other possible weal linmks in the engine, Use this procedure for calibrating tune-able circuits during testing - 1 - Low Speed Adjusters: to adjust for smooth idle 2 - Pop-Off Pressure: just off idle to 1/4 throttle ( in conjunction with low-speed jet). 3 - Low Speed Jet: just off-idleto 1/3 throttle 4 - High-Speed Jet: 1/3 -to 3/4 throttle 5 - High-Speed Adjusters: 3/4 to wide open throttle Learn how to change your Sea Doo pump oil in this easy to follow video. For Sea Doo pump oil change you will need tools such as a 10mm open end wrench, 10mm socket, 13mm socket, Jet Pump Oil , Grease and O-ring if yours is damaged. If your o-rings are in good shape you can re-use them. This Sea Doo pump maintanance should be done once a year. The following video will work for all Sea Doo 2-stroke pumps. And Lonnie we thank you for posting video. NOTE: If you find water in your Sea Doo pump oil? That means you have a bad pump seal and that the pump should be rebuilt with one of our jet pump rebuild kits
By Robert Boop When the weather outside gets chilly, it's important to take proper care of your watercraft to make sure it is in shape for when the water gets warmer and it's time to ride the waves again.
Winterizing your PWC will help protect it against the off-season elements during storage and get you on the water sooner when the riding season starts. If you don't take your Jet Ski, Sea Doo or Waverunner into a professional shop for winterization, here are a few tips on how you can do it yourself and save a little money in the process. (Be sure to read your owner's manual and all product instructions for proper safety and maintenance information.) Drain the engine Get ready to store your personal watercraft for the off-season months right after you take your final ride of the season. The first thing you'll want to do when you take your PWC out of the water is drain the water from the engine. The best place to do this is right at the loading dock when the craft is out of the water and the trailer is tilted so the stern is lower than the bow. Start the engine a few times letting it run for no more than 30 seconds to prevent the engine from overheating. While the engine is running, turn the handle back and forth. This drains any excess water out of the engine. Clean It Up Take extra care to thoroughly clean your PWC one last time. Wash down the exterior of the craft using the same kind of soap that you would use to wash your car. It might take some extra elbow grease to remove all the build-up, but removing the algae and grime now will be much easier than trying to clean it off after the storing period. When you're finished cleaning make sure there is no water in the hull, and the interior and exterior of the watercraft are completely dry. For extra protection on the exterior, finish your wash with a wax job and use a light coat of multi-purpose lube to coat any metal surfaces such as latches and hooks. Gas It Up Fill up the gas tank to prevent condensation over the storing period. Top off the fuel tank with the appropriate amount of gas stabilizer, according to the instructions on the container. Using stabilizer prevents the gas from getting gummy, which can eventually clog the carburetors and make for a messy problem. Start up the engine a few times for no more than 30 seconds. This not only allows the stabilizer to work its way through the engine and the carburetors but will drain any excess water out of the engine as well. Remember to be cautious of where you store the PWC with a full gas tank since gas is extremely flammable. Storage near any heat source or source of sparks is very dangerous. Oil It The next step is to spray fogging oil through the carburetors and spark plug cylinders. Begin by removing the air cleaners. This will allow you to spray the oil directly into the carburetor throat. Start the engine and spray the fogging oil into the throat of both carburetors while it is idling. Continue spraying until the engine stalls and then replace the air cleaners. Next remove the spark plugs, making sure the wires are grounded, and spray fogging oil into each hole for a couple seconds. Place a rag over the holes and push the start button of the craft. This will not start the engine but will allow the oil to coat and disperse internally. Clean any oil that may have dripped and then reinstall the spark plugs. Remove the battery Check your battery and battery chargers for specific safety instructions. Remove the battery by first disconnecting the negative terminal followed by the positive terminal. Store the battery indoors in a warm place such as a shed or garage. We do not recommend storing the battery in your house, as it can give off dangerous fumes. If the battery case is older, place the battery on a rubber mat for storage. Placing an older battery on concrete may cause the battery to conduct a current and eventually discharge it. Attach the battery to a trickle charger and remember to check the battery water level every month throughout the storage period. Storage Because your craft will have a full tank of gas, remember to be cautious about the location that it will rest. Put your trailer in a level position in the place where you intend to store the craft. The best way to prevent flat or corrupted trailer tires over the storing season is to take the tires off, store them indoors and use concrete blocks or a jack to hold the trailer in position. If you choose to leave the tires on, cover them with tarps or durable plastic bags. To prevent rotting, place boards under the tires if the ground is gravel or dirt. Once the trailer is in place, unlatch the seat of the PWC to allow air to circulate through and prevent any moisture from being trapped inside. Place steel wool or a rag inside the exhaust to prevent any animals or bugs from nesting there. Finally, place your cover over your PWC to keep it clean and protected while it's being stored. If you follow these simple winterizing instruction you will have a longer lasting life of your Jet Ski, Sea Doo or Waverunner. By Bobby Boop START EARLY: It's a good idea to get your Jet ski out of storage a little early and start it up. If you're taking it to a Jet Ski dealer to be summarized or get some PWC repairs, try to do it before the summer, when watercraft dealers tend to get overwhelmed.
WARM UP: Coax your PWC out of hibernation. If you stored your Jet Ski with some fuel in the tank and did not use a fuel stabilizer, condition the fuel by adding a conditioner Fuel System Cleaner and Stabilizer or drain out old gas (that's what I do). However, if you experience a no start and the fuel seems stale, then take your pwc to a qualified Jet Ski technician where trained Sea Doo mechanics are equipped to drain and dispose of fuel. MAINTAIN LUBRICATION'S: If you own a 4 Stroke engine, and didn't do it last fall, now's a good time to change the engine oil and oil filter, and drain and replace pump oil. You will also want to add grease to all grease fittings to keep bearings and seals lubed. For those of you who own 2 strokes, top off the oil reserve with fresh two-cycle oil, then drain and replace pump oil. You would want to grease fittings too. SECURE LOOSE ENDS: Check for loose wires. Check throttle and trim cables to make sure they work properly. CHARGE YOUR BATTERY: Charge and reinstall the Jet Ski battery. These tip will help you get a good start to keeping you Jet Skiing on the water and out of the shop. How to tell if you need a new impellerIf your Jet Ski, Sea Doo, Yamaha or Honda has a problem when you take off from a dead start (slipping)? Then you need to check the pump area to see if you have an obstruction. First look through the exit nozzle with a flash light. If you see rocks or debris in the pump veins. Odds are that is the problem. You also want to look at the back of the impeller blades to see if they are damaged/dinged. If you see dings or it looks damaged the odds are you need a new impeller and possibly a new wear ring. If you don't see anything from the back, then look from the front of pump to see if you have any rope, string or weeds attached to the shaft in front of impeller.
If your impeller is old and worn out? this would also create a slipping feeling when you take off. Impellers For Kawasaki Sea Doo Yamaha Honda Mikuni and Keihin are the two primary manufacturers of carburetors used in modern PWCs. While I have experience with both, most of my practical carburetion experience has been with Mikuni carbs on Kawasaki, Yamaha, and Polaris watercraft, both stock and modified. The majority of current Yamaha and Sea-Doo models, as well as most Polaris triples, use Mikuni carburetors, while all current Kawasaki models (except the '96 750 SXi) and many new twin-cylinder Polaris models use Keihin CDK-II.
To help you understand the tuning of these diaphragm-type carburetors, I'll break it down into four basic categories: external adjustments, internal adjustments, jetting, and pop-off pressure. EXTERNAL CARBURETOR ADJUSTMENTS Idle Adjustment Screw Under your flame arrestor, you'll see three adjuster screws: idle adjustment screw, idle mixture screw (low-speed screw), and high-speed adjustment screw. Both Mikuni and Keihin carburetors have these three adjustment screws. The idle adjustment screw is used to set the idle speed of your engine by opening the throttle plate (butterfly) and allowing air to pass through the carburetor. This screw is typically located near where the throttle cable attaches to the carburetor. On dual- or triple-carb models, there will only be one idle adjustment screw for the set of carbs. Turning the idle adjustment screw clockwise, or in, will increase the idle speed of the engine, while turning the screw counterclockwise, or out, will decrease the idle speed of the engine. The idle adjustment screw's goal is to achieve a smooth idle around 1000-1200 rpm while the PWC is in the water. Idle Mixture Screw (Low-Speed Adjustment Screw) The idle mixture screw, also known as the low-speed adjustment screw, affects the low speed of the engine, usually from idle to about one-quarter throttle. However, it also contributes to the total fuel supply all the way to full throttle. The low-speed adjustment screw works in conjunction with the low-speed jet. Carburetor manufacturers make it easy to identify which screw is the low-speed and which is the high-speed adjuster. The low-speed screw is the lower of the two screws on your carb, while the higher of the two screws is the high-speed adjuster screw. Both screws run parallel with the throttle shaft, and their location on the carburetor may vary by model. With the engine not running, slowly turn the low-speed adjuster screw in until it lightly bottoms out, being sure to count the screw's revolutions. Repeat the process for the high-speed screw, but be cautious not to turn the screws in too far and damage the carburetor or screw. If you have a service manual, compare your adjuster settings to the factory specifications. If your adjustments differ by more than a half turn from the stock boat, adjust the screws to the factory specs. Otherwise, adjust both screws back out to their original settings, which you should have recorded in case things get worse during the adjustment. If your PWC has a rough idle, start the engine and turn the idle adjustment screw until it reaches a smooth, steady idle. Gradually open the throttle from idle to about half open. If the engine "gasps" and nearly dies, it is lean. If the engine "chugs" or runs like it does when the choke is on or after it has been run slowly through a no-wake zone, it is rich. If it revs up cleanly, it is in the right ballpark. To adjust the settings, turn the low-speed adjustment screw one-eighth of a turn at a time. A little goes a long way, |
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