Q: Engine stalls sometimes but not all the time

Hello, Unfortunately, without additional information as to the make, model and year of your motorcycle it may not be possible to suggest what may be causing it to stall. Depending on whether or not it is fuel injected, or not will determine the approach to consider as this can be very different depending on your application. You will want to check basic things to start with such as spark plugs, fuel filters, be sure the air filter is clean and flows freely. Beyond this, you may also want to check the ignition coil(s) to be sure they are producing spark to the spark plug(s). I would suggest taking your motorcycle to your local dealer to have it looked at to determine what may be causing this. If this is a new motorcycle, it may also be covered under warranty as well.