I had a shocker today. Before I start I have broken in about 10 .21 engines and never have had this problem or any other problem.

1. Started to run in my new sirio. Heated it up to 120c with a heat gun. Started it up it was having trouble idling. Had a look inside engine and noticed a big chunk broken from piston.


2. After some cursing I took out a new nova rossi that I had spare in a box. The run in process wet o.k. Ran about 750 ml of fuel with no problems. Took the back plate off to put some after run oil on the rear bearing and again in the same spot a huge chunk of piston was stuck by oil on the backplate. Strange thing is that the engine was great during the run in process. Hotest the engine got was 113c. It remained steady between 90 and 113c during the run in process.


I use the method outlined in the run in bible in international rctech offroad forum. I have always used this process with great success.

Question would these issues be due to lack of lubrication in the fuel?

pics ?

Did you try taking the backplate off with the piston down?

what fuel u running ?? was it idled on box or driven ??

sound like a classic case of removing back plate with the piston not at TDC . been there done that.

think so.

if you look in the off road forum, he has admitted he did do it by the back plate removal. expensive mistake, but will be the last time i hope.

Yep after running Go engines for many years I was ignorant to the fact about those backplates. anyhow that's the way it is. I'm over it now but I tell you what its not a good feeling seeing two new engines destroyed in one day.: lol:

thanks for the support ADRO

anytime buddy.