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How Do I Adjust The Valves?

Remove the valve cover.

Remove the spark plug, put finger on plug hole and turn over the engine until you feel the compression stroke air pressure.

Turn the flywheel to close both valves.

Insert a narrow screwdriver into the spark plug hole and touch the piston. Turn the flywheel clockwise past top dead center until the piston has moved down 1/4". Use the screwdriver to gauge the piston's range of motion. PLEASE NOTE: This procedure must be performed for each cylinder on V-Twin engines.

Check the valve clearance by placing a feeler gauge between the valve head and the rocker arm. Clearances differ for the two valves and typically range from .002 - .004" to .005 - .007". Valve clearance specifications for your engine series are available by viewing our Engine Specifications Chart (pdf).

Adjust the clearances as required by turning the rocker screw. Once adjustments are completed, tighten the rocker nut.

Install the valve cover, using new gaskets, as required, and make sure the cover is secure.

I Have Excessive Vibration, Loose Bolts, Cracks & Gaskets Leaking

The one most single thing you can do to prevent your motor from shaking to pieces, loose bolts, cracks and gasket leaks is to ensure your propeller is not worn, bent or out of balance. If so, replace it immediately. Check by revving the engine to full throttle in a safe manner. Observe the skeg and front of the engine. If it begins to vibrate excessively after 2500 rpm, and especially at 4300 rpm, change the propeller immediately.

My Engine Stalls At Idle, Or Cuts Out At High Speeds

Several basic items should be checked. First, is the fuel tank full of fuel and vent open? Water in fuel or excessive amounts in water separator? Your engine should idle between 1250 and 1450 for stock motors and 1000 to 1200 for Mikuni aftermarket engines.

Is the fuel line pinched from a heavy object sitting on the line, or is a tight connection restricting flow? Are there cracks in the line or connections, allowing air to leak into the fuel system? If you placed your fuel tank near the front of the boat, did you use a recommended 5/16โ€ or 3/8โ€ fuel line? If you added a quick disconnect to the fuel tank, especially OMC type, you may be restricting fuel.

Do you have rope, weeds or wire wrapped around your propeller? Is your fuel filter dirty or plugged? Is your engine oil low?

Tip: If you use an in-line primer bulb, do not over pump the Mikuni carburetor aftermarket engines. These carburetors have very small needle and seat valves and if you over-pump the bulb, you can push small particles of debris past the fuel filter element and into the needle and seat where it will plug the carburetor. This can stop the engine or restrict fuel during acceleration or at full throttle.

Also, the Mikuni carburetors have a low speed idle jet on the side of the carburetor. (brass screw). If your motor experiences hesitation at throttle-up, turn the screw in. The idle screw is normally set at 1 and a half turns out, but it can be run as far as all the way in. Each engine and carburetor are slightly different.

If you are in a state that is using 10% ethanol and you aren't using our fuel tank and new fuel lines, the ethanol can deteriorate the older system and cause particles to enter the fuel system, plug up fuel filter, etc.

What Gear Ratio Should I Use?

We are proud to say that we are the only manufacturer that offers a wide selection of motors, drives, engines, performance components and gear sets. In order to get the best forward motion from your engine, whether stock or modified, light or heavy boat, sea level or high altitude you need the correct gear ratio.

Here is the recommended gear set for our short tail models:

14 and 18 Vanguard - 28 to 32 tooth top sprocket and 50 tooth bottom sprocket. (1:1.471 gear ratio) These models have low power and are sensitive to loads. So we gear them according to customer need.

23 Vanguard - 34 tooth top clutch/sprocket and 50 tooth bottom sprocket. (1:1.471 gear ratio) On some models we put a 52 tooth on the bottom for more low end power.

27 Kohler, 29 & 31 Vanguard - 36 top and 50 bottom (1:1.389 ratio). On some models, we put a 52 tooth on the bottom or 34 tooth on top for more low-end power.

35 Vanguard - 38 top and 50 bottom (1:1.316 ratio)

HD 4000 - 38 top and 49 bottom (1:1.289 ratio) HD 4400 - 38 top and 49 bottom (1:1.289 ratio) HD 45 Mag - 38 top and 48 bottom (1:1.263 ratio) HD 5000 - 38 top and 48 bottom (1:1.263 ratio) HD 6000 - 38 top and 46 bottom (1:1.210 ratio) HD 7000 - 40 top and 46 bottom (1:1.15 ratio) Black death 4500 - 38 top 48 bottom (1:1.263) Black death 5500 - 38 top 46 bottom (1:1.210)

If you hit the rev limiter, go to the 40 top.

Comments: If the customer has a large load, we would decrease the top sprocket by two teeth or add two teeth to the lower sprocket. This causes the engine to spin faster/prop to spin slower for more bottom end power. When the motor is new, it is easy/no expense to change the top sprocket/clutch ratio. Afterwards it is easier and less expensive to just change the lower sprocket size.

Performance Engines: When a customer adds power to his engine we use the above chart to change the gear ratio. Small 100 to 150 rpm changes can be made with one tooth changes such as our 47 and 49 tooth sprockets. Only a few of us use these.

Load: When a customer changes boat and/or increases load we make small adjustments by increasing the size of the lower sprocket by two teeth. Example, increase from 50 to 52 teeth will add 100 to 150 rpm. This can be done on all models except the mini 23 and 27 because the largest lower sprocket that will fit in the outdrive is 50 tooth.

All our lower sprockets are aluminum with an anodized hardened finish. They are interchangeable between Hyper, Sport, Hunter, Lite and Mini models by use of a mounting bushing. Specify when ordering the Hyper busing which has (7/8" drive) or the Sport/Hunter/Lite (25MM) drive shaft size. The cost of replacement sprockets is about $85 plus shipping.

What Spark Plugs Should I Use?

Our large block Vanguard engines come with a Champion RC12YC spark plug.

Although the gap can vary from .030 to .040 on new motors, they should be at .035. We have found that the AP3923 spark plug is a good upgrade. It is an Autolite Platinum plug and comes in AP and APP -the later being double platinum and lasts longer. It is a slightly cooler plug and although the details regarding why we use this are long, we like to use this plug on performance motors and/or when replacement time comes.

Don't underestimate the value of having fresh and well performing spark plugs. For starting, acceleration and top speed - good plugs, produce good results. They are the heart of your engine.