95 magnum 425 started missing out at high speed what could be causing this.

 

Start at the basics. Replace the plug first,fresh fuel if you suspect it as a problem.Clean air filter or replace it.Check for any leaks around the carb intake manifold.Plus you can draw
some gas from the bottom of the tank and check for any water contamination that may be causing problems. If it doesn't help,you may need to clean the carb,adjust the float level or may need a new carb kit.Plus don't over look things like rocker arm clearances and check out the cam as it fell into the group of year models where some had excessive wear along with the 500 engines. Beyond that it may be an electrical problem You just have to eliminate the simple things first and hopefully you'll find it. Plus here's a good manual with different trouble shooting guides. http://gh-ftp.com/ORV%20Manuals/Pola...e%20Manual.pdf

 

Did the problem suddenly appear, or did it start as a minor misfire and get worse?

I would also start with the basics....

Pull the seat, and air cleaner. Check for obsruction or clogged filter.

Pull the fuel line off the carb and drain about 10oz into a clear soda bottle. Look for water. Check to see if fuel filter is plugged. When in doubt, drain the tank and replace with fresh fuel. Replace the fuel filter.

Pull the plug, check for fouling. Check gap and do a compression test. Check plug wire for rubbing, check boot for proper resistance, trim back wire about an inch and reinstall boot.

Remove the tank, and the valve cover. Inspect the cam and rocker arms. Check valve clearances.

These things can be done for cheap/free, and should take about an hour.


If all this checks out, I would then clean and reset the carb. Replace the spark plug and drive again. If you can, install a tach and look at the RPM that the miss occurs at. You may have binding clutches causing you to hit the rev limiter.