Every spring, skis come into our shop in Howard Beach with the same set of problems — dead batteries, gummed injectors, cracked fittings, seized cables. Most of these problems are avoidable. They happen because riders park the ski in October intending to deal with it "later," and later turns out to be May, after the damage is already done.
New York winters are real. Temperatures in Queens and Brooklyn regularly drop into the teens. If there's residual water anywhere in the cooling system, it freezes and cracks. If the battery sat discharged for four months, it's often not recoverable. If the fuel wasn't stabilized, it phase-separated and now you have a gummy mess in the injectors. Winterization is not optional in New York. It's cheap insurance against expensive spring repairs.
Here's what actually needs to happen — and what to watch out for if you're doing it yourself.
1. Flush the Cooling System
Salt and minerals accumulate in the cooling passages over a season of riding. A proper end-of-season flush clears this out before it sits and corrodes over winter. It also ensures no saltwater is left to freeze in the passages, hoses, and fittings.
You need a garden hose and the ski's flush port — most modern Sea-Doo, Yamaha, and Kawasaki models have one. Run the engine while flushing with clean freshwater for several minutes until the water runs clear. Then run the engine briefly after shutting the water off to expel remaining water from the cooling circuit.
What we see go wrong: people flush with the garden hose but don't run the engine long enough to actually clear the entire system. Residual saltwater pockets sit in passages and cause pitting corrosion through the winter. Take the time to do it right.
2. Fog the Engine
Engine fogging is one of the most important and most skipped steps in winterization. Fogging oil sprayed into the intake and cylinders while the engine is running coats all internal surfaces — cylinder walls, piston rings, intake valves — with a protective film that prevents corrosion during storage.
Without fogging, bare metal cylinder walls exposed to residual moisture over winter develop rust spots. When the ski starts up in spring, those rust spots act like sandpaper against the piston rings and the ring seals start to degrade. It happens slowly, and riders usually don't notice until compression starts dropping a season or two later.
On a supercharged Sea-Doo or Kawasaki, you're fogging through the air box intake. On naturally aspirated Yamahas, same process. Use a quality fogging oil — this is not the place to cut corners with a generic spray. Run the engine, spray in the fogging oil per the can instructions, kill the engine while spraying for the final coat. The idea is to leave the cylinders coated when the engine stops.
3. Treat and Stabilize the Fuel
Modern ethanol-blended gasoline has a shelf life of roughly 30 days before it starts to degrade — much shorter than the 4–6 months most skis sit in storage. Ethanol also absorbs moisture from the air, which leads to phase separation: the ethanol and water sink to the bottom of the tank as a separate layer, leaving the remaining fuel depleted of the ethanol content it was originally mixed with.
Add a quality fuel stabilizer to a full tank of fresh fuel before the last ride of the season. Run the engine long enough to circulate the treated fuel through the entire fuel system — injectors, fuel rail, and all passages. A full tank minimizes the air space above the fuel where condensation forms.
Skipping this step leads to varnish deposits in the injectors and fuel delivery issues in the spring. An injector cleaning costs more than a bottle of stabilizer. Do it every year.
4. Service the Battery
A battery that sits discharged through a New York winter often doesn't come back. Lead-acid batteries sulfate when left discharged — the lead sulfate crystals that form on the plates during discharge harden permanently if the battery isn't recharged. By spring, you're buying a new battery.
Before storage: check the battery's current charge state. If it's low, charge it fully. Then connect it to a battery tender or smart charger that maintains the charge without overcharging. Most modern battery tenders have a maintenance mode designed exactly for this. If you can't leave the ski plugged in through the winter, at least store the battery indoors in a warmer environment and check the charge mid-winter.
Disconnecting the battery from the ski is a good idea — even a small parasitic draw from electronics can discharge a battery over months of storage.
5. Lubricate Everything That Moves
Cables, pivots, steering joints, and throttle mechanisms need to be lubricated before storage. Things that are dry going into winter often come out seized. Throttle cables that are sticky or stiff in spring are a safety issue and usually avoidable with five minutes of proper lubrication in October.
Grease all grease fittings. Use a waterproof marine grease on anything exposed. Apply a light coat of corrosion inhibitor to any exposed metal components — battery terminals, ground straps, electrical connectors.
6. Inspect and Cover Properly
Do a visual inspection before the ski goes away for the winter. Anything that needs to be fixed — a hull crack, a damaged fitting, a worn impeller — is easier and cheaper to address now than in April when we're slammed and lead times extend. If something looks wrong, note it and deal with it before or early in the storage period.
Cover the ski with a fitted cover, not just a tarp. A fitted cover keeps moisture from accumulating, keeps pests out of the engine compartment, and protects the hull and gelcoat from UV during late-season sun. Store on the trailer in a position where the ski drains forward — you want any residual water to run toward the bow, not pool in the bilge.
When to Bring It to Us
If you're not confident in any step of this process — particularly the engine fogging or cooling flush — bring the ski to us for a full winterization service. We do it correctly, every time, and it costs a lot less than what we charge to fix the things that go wrong when it's not done right. We're in Howard Beach, Queens. Call us at (347) 225-5113 — we get busy in October, so reach out before the end of the season rather than waiting until the last minute.