hi guys and gals, need some advice on what to do, i ran my engine way to hot and there is some serious pitting on top of the piston, in the center of the piston its fine but anywhere around that has alot of small pits, more being towards the exhaust port, the piston also has a deep scratch in the side towards the top, the head button or conical head also has a huge amount of pitting, both the piston and the head button have a huge amount of pitting and there surfaces are like sandpaper. this engine is not that old as it was due for its first new con rod, it has around 5 liters of fuel through it from new, the sleeve just has a few scratches on the inside, my question is should i replace the parts that are damaged hoping that the rest are ok or buy a completely new engine, the engine is a IDM RCW, the same as a picco torque, so parts would be cheap but i still dont know what to do. i am almost certain the damaged was caused by the engine operating at to high of a temperature, but could this happen in just one race day?, i cleaned out the engine about 2 weeks before the race day and it was fine

I had a similar thing happen with a Nova, but my trouble came from using a higher nitro percentage. The advice I got was: change the button head and use a small amount of metal polish on the top (only the top) of the piston to polish out most of the pitting.

You also want to replace the conrod and may consider adding a .05mm or .1mm of head shims. I did this for my engine and it ran well, as fast or faster than before. Engine still runs and raced 5-7 liters after the pitting(detonation).

Not sure how big the scratch on the side is but if not too big should not be an issue.

Thanks HHH for the reply, for some reason i dont thing the pitting will come out of the piston, the pitting is really bad and the pits them selfs look quite deep into the piston, im running 0.30 mm head shims witch is the standard for the Torque, i am also using 25% fuel

Feel the bearings with your finger. If they are smooth, then I would recommend a new piston/sleeve/rod/button. Make sure you have at least .50mm of head shims. That makes a head clearance of .50mm. I run .55mm of shims in my picco based engines. .12, and .21 engines.

The picco .21 engines including the idm come with .40mm of shims. That's too low for 25% nitro. It's too low for 20%. The stock clearance is ok for 16%.

thanks for your input, tryed using a small amount of metal polish on the top of the piston, made it abit smoother but there is still those deep pits in it, really at this point it needs a new Rod/liner/piston/head button, the bearings are not the smoothest, but seem to be ok

New engine time!