KDXRIDER.NET

Advice please on whether i need to strip down the bottom end of my 220 motor having found damage to the crank?
Owned the bike for around 5 years, recently started tearing the bike down to add some kx mods etc, recently started stripping the motor & came across the crank damage shown in the picture. My question is... do i need to break open the cases to investigate further or could this be damage from years ago, the reason im unsure of whether to strip is... the piston is in very good condition, no gouges no real scratches outside & underside, rings are fine too, underside of the head is undamaged & pretty clean,cylinder looks pretty good except a couple of very minor scratches (just about feel them with finger nail). Crank bearing feels nice & tight with no up & down movement on the con rod!
I intend to have the cylinder plated & a new piston kit anyway but if i can get away without touching the bottom end then thats great!
Just for info... the motor was running fine prior to taking it out the bike, no strange noises/no lack of performance/power, no oil leaks & good compression. Any advice will be great regarding stripping fully or what effect if any will leaving the crank like this & rebuilding the top end only have?

It's probably damage from the original piston going kaboom. If you have been riding it for five years, the crank seals are not leaking, there is no slop from the bearings, and you haven't found any parts, pieces, or otherwise unknown foreign objects in there, I would say you are good to go.

I would agree with SS109.

Just what i was hoping Thanks for the answer!

the "damages" must be normal I have 3 cranks from 3 different 220 motors (parts bikes) and they all have the same grinding you show in you picture, it's maybe just some removed material to balance the crank..

I also agree with SS109, you should be good to go, but depending on your budget/time you should think about opening the case and change the crank bearing and seals to get better peace of mind..

Yeah budget is an issue with splitting the cases, but i have also checked the left crank bearing with a grasp on the flywheel, this resulted with zero movement in all directions, also clean & dry behind the flywheel. No movement from main bearing!
Based on these facts i have now no reason to belive that splitting the cases would be of any benefit.
I intend to flush the engine through a couple of times just to see if anything appears while it's out of the frame.