250 Yamaha 4 stroke not looking good

[steplift20]

250 Yamaha 4 stroke only runs when you give it gas( push the throttle forward) stalls in neutral , won't run
Changed all the filters
Pulled the spark plugs ( this is where it gets ugly) the bottom plug ,the electrode is gone,broken off. Someone told my son that the motor is toast,
Is there anything that I can check? Anything I missed? I know he needs to replace a throttle cable but what happened to the plug? I'm all ears,thanks

[phatdaddy]

I d start with compression

Maybe put a borescope down in that cylinder

[spareparts]

compression test before you go any further, if that cylinder is low, youve probably got a dropped valve. Amazon bore scope that runs on your phone will show you the extent of teh damage. If its a salt water motor, its not worth fixing. Reman powerhead installed will run around $7000+

[steplift20]

Ok will do that but what if the compression is good? Should all the cylinders be around 110 psi? And if that cylinder is bad than we are screwed I guess. But before that I have to check the compression. One step at a time. Personally I don't like 4 strokes and definitely do not like electric vehicles. Sometimes progress is not good.

[spareparts]

compression should be around 175 depending on the gauge. If its good, take a look with one of those bore scopes, if you dont see any damage, throw plug in it and see how it runs

[steplift20]

Will do spare. When you relocate to New Jersey let me be the first one you tell.