Apologies if this has been covered elsewhere,..after how many hours running should consider changing either the conrod or the crankshaft? I have Novarossi based engines .21 on-road engines. Conrods where changed after break-in but just wondering how often they should be changed now as they don't really show signs of wear?

Thanks in advance

Usually its good practice to check During regular maintenance, if it seems to have a hesitation in its operation (piston) of the conrod, like play then its time to replace it. I have had motors last 3+ gallons on a rod, and others got replaced after a race meet. When in doubt, change it out! Running conditions etc. Can vary from person to person and motor to motor. Is it an ISON .21 7 port? What are you running it in?

Thanks for that. Its a Mito WC engine.

I believe that has the new R4 conrod, which is supoosed to be more durable.

Novarossi has listed that you should replace it after the break in and then every 5 liter.

My experience is that it is no problem to replace it after the first 5 liter, that is about the break in and 1 or 2 races and then you can go for a longer period. But it is up to you to invest a 40 dollar rod from time to time or risk a 400 dollar engine....

Ok Roelof, i have been stung in the past with a perfect looking rod (no excessive play) only for it to snap!! Although i cannot be 100% sure how many minutes runtime were on it as I was not logging it in a book at the time

Actually in my research i came across this useful tool to help me keep track of my engine parts, (www.rcnitroenginetracker.com) as usually i loose the piece of paper i have written stuff down on. Hopeful it will help me

Play is no indication to replace the rod. The material itself is getting weak due the flex movement on it. You will not see it and if you could attach a sensor it well not measure it but it is continious bending.

ok thanks Roelof

Usually I have no idea of the runtime on my conrods as i always loose where I have written it or just even forget to write it down.
Thanks to the forum here I downloaded the rcnitroenginetracker and I find it's very useful.
Thanks guys.
Personally fer me I like to break in the engine do 1 meeting then replace the rod.
After that about every 5 hours runtime for me.

Just change the rod every 10-15lt, that would give you about 6-10h of running.
I can vouch for this, although basic it keeps track of usage.

Bit tricky when you are running 3 different engines though

I am going to try that app above. Seems like it will make it easier for me. Will let you know how it works out

You can change the Rod every 20 liters if you always preheat your motor to 220*F before startup...You might get to 25 liters if you use some NMF+bestline (anti-vibration additive) in your engine....

Whow 20 litres, that's a lot of run time on a rod . Is that for .21 on-road? I do use and engine heater each time before startup