My 1998 yamaha warrior atv isnt starting the starter is turning the crankshaft but the spark plug isnt getting any spark. My mechanic says that the catch coil in the magneto system could be junk but he needs to know the voltage that the coil puts out to check to see if its running right. Any ideas

The cold weather may cause your Yamaha Timberwolf to experience hard starting, several months and no use, or a stale fuel supply. Start by replacing the spark plug, if the engine still does not fire up, clean the carburetor and make sure all the hoses are connected tightly with no air leaks. If none of these strategies work, the carburetor may need to be adjusted or replaced. You may want to take it to an experienced mechanic if you are unable to get the engine started.

Sounds like a fuse. Yamaha uses a Negative start button. So start button shoul always be hot. When pressed it grounds circuit (closes) sending voltage thru solenoid. You should have power at solenoid on one of the small wires.

I'll bet there's a starter relay under the seat.

clean battery connections. still same replace starter selnoid (sp).

Sounds like you burnt out the starter Take it to Auto Zone they should be able to see if the Starters any Good a starter should not spin over more than 10 seconds copper windings are that good in jump Starter just about every starter is from Japan, as for the no starting sounds like the Carb has issues does your fuel smell like varnish

95% of the time it's the Stator / Pulser coil in the L.H. side of the motor.

Check spark plug, that sounds like it's running little too lean.

1. replace the spark plug with a new one...
2. check all your on/ff - kill switch(s)
3. If it still will not spark, you will probably need to find a pro with a service manual to start checking electrical system values...

Check the choke or motor compression.

Go on ebay and buy a new CDI computer those bikes are notorious for computer failure.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/brandon_79b580f5a99c4386