Guys,

I have a Novarossi NSR12S5, and all through its less than 30 tanks of fuel already I have had two pistons with the lower skirt broken. While I was running the engine I did not lean it, and the engine keep running under 100F. What gives? Did I had a lemon, or am I wrong in setting the needles? I am running NR CTF6 plug, 30% nitro, on a FW05. Needle setting is a tad less than 5 turns main, 3.5 turns idle. Should I call a quit with this engine, or should I get the piston/liner, conrod and piston pin again and give it one more try?

Also, now I have two liner perfect without scratch, anyone knows where I could get just a piston so that I could save some $$$?

30 tanks is alot I think,and plus 2pistons I think its time to let it go . Set her loose in the nitro pasture on your shelf,,,

30 tanks isn't that much. It's gotta be less than a gallon. Did you add a .1mm copper shim to the head? You may have to do that running 30%. TopGun???

I was curious when was the last time you changed your Conrod? My experience similar to this was the cause of a loose bushing on the rod. Do to the play everytime it rotates the rod seems to move around inside freely causing it to hit. If you think about it the slightest millimeter off can make your piston head extend itself going to far or down making the travel of your piston & sleeve a little longer either way. I don't know but this is what I experienced so thought you might want to know if it will help.

I was curious when was the last time you changed your Conrod? My experience similar to this was the cause of a loose bushing on the rod. Do to the play everytime it rotates the rod seems to move around inside freely causing it to hit. If you think about it the slightest millimeter off can make your piston head extend itself going to far or down making the travel of your piston & sleeve a little longer either way. I don't know but this is what I experienced so thought you might want to know if it will help.



Hope you can get this problem resolved.

Sorry guys.

Actually I use 2 .1mm shims on the head to break in the engine. The conrods on both cases are like new, with the bushings sitting fit on both sides....

Chances are, the sleeve is grooved or slightly warped. This will caused the piston to chatter at high RMP and shatter the skirt.

did you mean 100C ?