2012 KX450 Interesting piston marks...

[Chipper1012]

I recently did my first top end job on my 2012 KX450. Nothing was wrong, I bought the bike used with unknown hours and wanted to start fresh. The cylinder looked great and so did the piston. Well, on the bottom of the piston I noticed 4 places where it looked like there was some sort of contact. You can see where the aluminum was being "tapped". Has anyone seen this before?

 

Like I said, the bike runs fine and isn't noisy. I am about to install a new Wiseco piston. Should I be concerned this will happen to it, also?

 

I have attached pictures.

Thanks,

Chipper

 

 

[adam8781]

Thats a bit different.

 

few thins it could be. Crank play allowing the piston to drop to low

poorly cast stock piston (never seen that before tho)

the piston has become so worn it is rocking front to back in the bore making contact with the crank.

 

Be crazy to not replace

 

• crankshaft
• crankshaft bearings
• cam chain
• piston kit

I would also suggest new valves. I just built a 12 kx450f from scratch for a customer with all the parts I just listed plus new valves and a 490 big bore and tokyo mods remap. It has alot of hours and the valves tested very poorly with a leak down test even though it ran quite well.

 

check out the build if you like @403mx thing is a FRIKEN MONSTER now

[skorpan777]

Look if you can see any marks in the case/crank , if not there is probobly from manufaktur process

Edited January 29, 2017 by skorpan777

[Endoair]

I've never seen that before but I'd put it back on the crank and slowly work the piston up and down and see if you can tell what it might line up with. That would probably give you your next clue and point you in the right direction.

[skorpan777]

I Google a picture and there are marks there from manufacturer process 

[Chipper1012]

Update- thanks for everyone who replied. I rotated the crank a few times and looked for marks or any indication something was hitting. Nothing... Here and on another forum someone suggested that those were casting marks from the original manufacturing. I went ahead an put the new wiseco piston in and all is good. I haven't rode the bike yet, just let it idle for a few minutes to get a heat cycle on it. I can say that it idles much smoother than before and unless it's my imagination, the motor sounds a tad bit less noisy. 

Anyways, thanks for the input. If the bike grenades itself on the first ride, I'll let y'all know.