100LL aviation fuel (AvGas) serves as the primary high-octane fuel for turbocharged aircraft piston engines and is also suitable for use in smaller, naturally aspirated engines. You can run AvGas in your 2-stroke outboard engine. 100LL AvGas has a similar lead content, distillation curve, and specific gravity to some racing fuels. Many use blends with pump gas to get to the right octane rating. First, your baseline must be correct and we understand which octane rating is being used for your specific fuel. In the U.S., we use the average of RON plus MON, also known as AKI, (or RON+MON / 2 = AKI). This equals the minimum octane rating for unleaded motor fuels and is the number you see at the pump at your local gas station. In the example pictured, we are using aviation fuels, since this is a common and affordable way to increase the octane of pump gas by blending. Here you can see, for example, 100LL AV GAS is the equivalent of 105 AKI, so a 50/50 blend with 91 from the pump gets you 98 AKI octane (105 + 91 / 2 = 98). In Europe (EU), the octane rating on the pump is simply the RON figure. EU 95 octane = US 91 octane and EU 98 octane = US 93 octane. You can apply this simple math to any fuel once you know the octane rating method. You might be able to find a local airport to buy 100LL fuel. Be sure to bring your 5-gallon jugs or some may allow you to pull in your boat. https://www.airnav.com/fuel/local.html

When installing bolts, you can lubricate the threads and underside of the head with 2-stroke oil. You can also snug the bolts in a box pattern, starting in the center. The cylinder head, exhaust plate, and crankcase bolts on the Mercury 2.5 Liter 200 HP should torqued in a series of passes, increasing in torque from just tight to final torque. The pattern is circular, starting in the center and moving outward toward each end. If the head bolts aren't torqued properly, the head gasket may fail. This can lead to several issues, including Loss of compression, Mixing of oil and coolant, Exhaust gases in the cooling channels or oil ways, Cylinder head erosion, and Cylinder head overheating and warping. Here are some steps to check the torq on your cylinder head bolts on a Mercury 2-stroke outboard motor block: Run the outboard for 30 minutes to an hour to warm the block Let the block cool for two hours When the engine is cold, follow the torque sequence and tighten each bolt individually Loosen the bolt a quarter turn and retorque it to 30 ft-lbs.

Numbered drill bit sizes range from 80 (smallest) to 1 (largest). The numbers on numbered drill bits relate to wire gauges, so larger numbers indicate smaller drills. Mercury 2-stroke outboard carb jet sizes, on the other hand, are related to thousandths of an inch which matches typical jet sizes found in both main and air jets in WH, WMV, WMH, and other carburetor types. A jet size primary passage bore in diameter indicates flow rate. Larger main jets (which carry fuel) are "fatter", while, larger air jets (which carry air) make those circuits "leaner". While jets should be reamed or bored (not drilled) to ensure a consistent diameter, drilling jets can be an affordable way to make bigger jets to save or tune a motor that is too lean. This numbered drill bit chart is correlated with typical outboard carburetor jet sizes. Numbered drill bit kits can be purchased at your favorite tool stores. We've created this chart as a convenient reference with the most common numbered drill bits sizes (39 to 59) used to enlarge more common smaller jets to larger sizes when otherwise not available to purchase. To drill a jet with numbered drill bits, you can try these steps: Run the engine with the stock main jet, and determine if too lean If lean, use a drill bit that's one size larger to drill out the jet Run the engine again and take another read Repeat until jetted properly

This is a free online resource to find mostly out-of-production, no longer available OMC (Johnson and Evinrude) Racing Parts Diagram Manuals with specifications for 2-stroke outboards. All are in PDF files making them available for online download to your laptop or as a file to your mobile phone. 2-Stroke Parts Catalogs OMC A-Stock APBA Hydro Outboard Parts Diagrams OMC SST-45 APBA Tunnel Boat Motor Parts Diagrams OMC SST-60 APBA Tunnel Boat Motor Parts Diagrams

Instructions: 1. Connect one lead to the yellow/red wire on the terminal of the solenoid. Be careful as these connections are close to the hot terminal! 2. Connect the other lead to the 5/16" terminal on the solenoid with the HOT battery cable. This is the heavier gauge RED cable coming from the positive side of your battery. 3. Once clear of the powerhead, moving parts, propeller, and opened gas fumes, push the Remote Outboard Starter Switch to crank over the motor.

We've included free instructions that can be downloaded here in PDF on how to install our SeaStar Hydraulic Steering Cylinder Seal Rebuild Kit with the proper required Pin Wrench included as well as new end caps. Free PDF Install Instruction Here: This Replacement Parts Rebuild Kit is compatible with Multiple Sea Star Marine Hydraulic Steering Systems including Part Numbers: HC5345, HC5347, HC5348, HC5358, HC5445, HC6345, HC6750, HC6751, HC6752, HC6753, HC6754, HC6755, HS5167

This is a free online resource that contains every Mercury Serial Number Series for every 2-Stroke and 4-Stroke Outboard Model built in the USA and Europe. The PDF file below has all outboard motor models produced in 1963, 1964, 1965, 1966, 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, and 2005. It includes engines with horsepower ratings from 2.2 to 300 HP such as the 135hp, 150 Black Max, 150 Blue Line, 150 XR2 XR4 XR6, 175 EFI, 200 XRI, 200 EFI, 200 Carb, 225 Pro Max, 250 Optimax, 300 X, and 300 XS. Click on the PDF file below to download online free.

This is a printable Mercury V6 Outboard Single Trim Tilt Ram (Long) Assembly​ and exploded view parts diagram.

Here is a simple way to check the condition of a 12-volt outboard marine battery in your boat with a simple battery checker. The motor is off: 1. Connect the battery checker to the battery terminals. The red connector goes to the positive terminal and the black connector goes to the negative terminal. 2. The light that illuminates under the "battery condition" will indicate the battery's approximate voltage charge. 3. A fully charged and healthy battery should read 12.6V. A partially discharged battery that needs recharging would have a 12.1V to 12.5V level. The motor is running: 1. Connect the battery checker to the battery terminals. The red connector goes to the positive terminal and the black connector goes to the negative terminal. Make sure it is safe to run the motor. 2. The light that illuminates under the "charger output" will indicate the stator's approximate voltage charge. 3. A healthy charging system should read 13.2V to 14.5V. A charging system that may need attention might read under 13.1V or over 14.6V at idle. Please note, as a reference, a 12-volt lead acid battery will deliver about 12.7 volts when fully charged, but only about 11.6 volts at 20% capacity. Meanwhile, a lithium battery will deliver 13.6 volts when fully charged, and 12.9 volts at 20% capacity.

The mechanical fuel pump on 1976 to 2005 Mercury 135, 150, 175, 200, 225 HP 2-Stroke V6 outboards (Black Max 2.0 and 2.4 Liter and 2.5 Liters) is a crankcase-pressure-operated, diaphragm-type pump. Crankcase pulsating pressure (created by the up-and-down movement of the piston) is transferred to the fuel pump by way of a passage (hole) between the crankcase and the fuel pump. Some symptoms of a bad fuel pump or restricted (lean) fuel flow include: 1 - Loss of fuel pump pressure 2 - Loss of power 3 - High-speed surging 4 - Preignition/detonation (piston dome erosion) 5 - The outboard cuts out or hesitates upon acceleration 6 - Outboard runs rough 7 - Outboard quits and cannot be restarted 8 - Outboard will not start 9 - Vapor lock Remove, Clean, Inspect, Rebuild, Install: 1. Clean fuel pump housing, check valves, pulse chamber and pump base in solvent, and dry all but check valves with compressed air. 2. Inspect each check valve for splits, chips, and proper sealing against the pump housing. 3. Inspect boost springs for weakness or breakage. 4. Inspect the fuel pump housing, pulse chamber, and base for cracks or rough gasket surface and replace if any are found. 5. Inspect the fitting on the fuel pump housing for loosening or any signs of fuel or air leaks. Replace or tighten the fitting if a leak is found. 6. Insert new retainer from the rebuild kit through plastic disc and rubber check valve. 7. Install new check valves and retainers into the fuel pump body. 8. With the new retainer installed in the pump body, break the retainer rod from the retainer by bending sideways. 9. Install the new rod into the retainer cap and, use a small hammer and punch to tap the rod down into the retainer until flush with the top of the retainer. 10. Place the boost spring into the pump body and place the cap onto the boost spring. 11. Assemble the remainder of the components as shown and install retaining screws thru to align. 12. Install the rebuilt pump onto the powerhead. Torque to 55 Ib. in. (6.0 N·m). 13. Install hoses onto proper fittings and secure them with straps. 14. Make sure you run the engine and check for leaks before launching the boat.

Detonation in a 2-cycle outboard engine resembles the “pinging” heard in an automobile engine. It can be otherwise described as a tin-like “rattling” or “plinking” sound but most of the time you can't hear it to due to the engine, wind, and water noises. Detonation is an explosion of an unburned portion of the fuel/air charge after the spark plug has fired. Detonation creates severe shock waves in the engine and these shock waves often find or create a weakness that can quickly destroy the top of a piston, cylinder head/gasket, piston rings or piston ring lands, piston pin, and roller bearings. A few of the most common causes of detonation in a marine 2-cycle outboard or jet boat powerhead are as follows: 1. Over-advanced ignition timing. This could happen simply by the top throttle arm or the linkage becoming loose and moving the timing adjustor. Or the timing advance box malfunctioning, all unsuspectedly. 2. Use of low-octane gasoline. The lower the octane the faster the fuel burns, and if the fuel burns before the piston has a chance to reach top dead center, it pounds the top of one or more pistons. 3. Propeller pitch too high (engine RPM below recommended maximum range). AKA lugging the motor. 4. Lean fuel mixture at or near wide-open throttle. 5. Wrong or bad spark plugs (heat range too hot, incorrect reach, gap, or cross-firing). 6. Inadequate engine cooling (deteriorated cooling system, or bad water pump). 7. Combustion chamber/piston deposits (result in higher compression ratio). There are other reasons for blown outboard motors, stuck or melted pistons, and broken rods; feel free to email STVracer @yahoo.com photos and we can help you identify what went wrong.

These are the factory Mercury V6 Torque Specs for rebuilding a 1991-2005 2-stroke outboard. Block stamps could include AA, BB, CC, EE, F, FF, NN.