Sparks from exhaust

I’ve never had that problem but it is pretty easy to imagine it.

Does your engine smoke excessively or do you run it at idle for extended times?

It is possible that the injection pump timing may need adjustment.

You could also try some form of fuel treatment. Look for one that addresses carbon buildup.

How does it start and run otherwise?

as the injection timing is concerned make sure to do your research on this before attempting to adjust factory settings. some engine injector  pumps have to be shimmed to change timing. any engine can product sparks thru the exaust that is why to get forrest rated engines have spark arrestor screen on outlet side of muffler to prevent fires. usally I notice sparks when a piece of equipment is used at night, I would think this is carbon burning up, it is tuff to say over the net if you have excessive sparks coming out of exaust, I would think if the engine is running well you should be ok, if engine is running ruff then when you figure out the issue ,sparks should go to what ever is normal for that engine..