counterbalancer is bad
Under the air filter box, above the engine crankcase, behind the belt/clutch housing.
The 1997 Polaris Scrambler 500 is a two-stroke ATV. It features a 500cc engine that is designed for high performance and quick acceleration, typical of two-stroke engines. This model is known for its versatility and capability in various riding conditions.
To determine the year of a Polaris Scrambler 500, locate the Vehicle Identification Number (VIN) on the frame or the engine. The 10th character of the VIN indicates the model year; for example, "A" corresponds to 1980, "B" to 1981, and so on, with letters skipping "I," "O," "Q," and "U." Alternatively, you can check the owner's manual or contact a Polaris dealer with the VIN for assistance.
Knocking is usually associated with worn main and rod bearings.
The drain plug for the crankcase on a 1997 Polaris Scrambler 400 is typically located on the bottom of the engine case. You may need to remove the skid plate for better access. Look for a hex or bolt-type plug, which is often positioned towards the rear of the engine. Always ensure to have a drain pan ready to catch the oil when you remove the plug.
The piston measurement for a 1995 Polaris Scrambler 400 typically has a bore of 82 mm and a stroke of 75 mm. This engine configuration contributes to its overall displacement of approximately 400cc. For precise specifications or replacement parts, it's always best to consult the owner's manual or a service manual specific to that model.
it could be your valves or your engine
Mine did the same, mine was a motor mount.
The Polaris Scrambler 400 typically produces around 40 horsepower. This ATV is known for its balanced performance, combining power and agility for both trail riding and recreational use. Its liquid-cooled, four-stroke engine offers a strong output for various terrains. Always check the specific model year for exact specifications, as they may vary slightly.
If your 1999 Polaris 400 Scrambler 4x4 has spark and is getting fuel but still won't start, there are a few potential issues to consider. Check the compression in the engine, as low compression can prevent starting. Additionally, inspect the ignition system components, such as the spark plug and ignition coil, for any faults. Lastly, verify that the engine timing is correct, as improper timing can also cause starting issues.
2 cycle engine oil. I prefer to use a synthetic designed for ATV's and Snowmobiles. It doesn't smoke as much and stinks much less.
Knocking as opposed to pinging or ticking, usually means seriously worn bearings of some sort. Time for an overhaul.