Picked up a kd100 that seemed to run pretty good for a decent price for me and kids to play on. Runs pretty strong when cold, but after a few minutes it runs rough or won't run. Sometimes it backfires like crazy, usually have to hold it about 1/3 or 1/2 throttle to keep it and it slowly dies out or just won't stay running. I have mechanical ability but no experience on 2 strokes. Thank you in advance for any help.

 

Welcome to KF and congrats on the new ride.

My first thoughts are to test the plug wire and coil. Of course, a manual is necessary if you plan on keeping the ride.