Constantly have to tune my .21 O.S, help!

[skimbum686]

I just put a new . 21 O.S in my SC8 and i broke it in fine and it ran fine for a lil while. now every time i start it i have to tune it and i can never get a good idle. ill get a good idle take it around the driveway and when i come back it is reving high sometimes way high . eny ideas?

 

[lesclaypool]

Have you checked out this tuning guide here? https://www.rcnitrotalk.com/forum/showthread.php?t=76808

Follow it exactly and you'll be golden. That is, providing you don't have any mehcanical issues, ie. air leaks, binding, not fully broken-in yet.

 

[Metalhead Matt]

I'd seal er up before going any further. Read the tuning tips and flow chart sticky at the top of the nitro forum. All the sealing info you need.

 

[2revo1maxx]

You probably have to richen the high speed needle. A well tuned engine should seem a bit sluggish and rich until it warms up. I'm gonna guess and say that you're trying to get it to perform well before it's up to temp. An engine will lean out as it warms up. By running lean the rpms will hang up a few seconds after you let off the throttle.

It should have a nice clean idle, which may seem high, but it's fine as long as the truck isn't trying to drive away at idle.

I would set the lsn at factory and never touch the mid range needle. Make sure you have a proper idle gap then richen the hsn until you know it's running too rich, then gradually lean it back to good performance.

What's the weather like outside?

---------- Post added at 5:35 PM ---------- Previous post was at 5:33 PM ----------

And make sure your throttle linkage is set properly.

 

[Extreme RC Mods]

Just wait until the engine is fully warmed up before you start tuning. As mentioned, a properly tuned engine will run rough and sputter until it's warmed up, at this point it will naturally lean itself (from cold to warm) and run the way it should.

 

[skimbum686]

thank you ill try that i live in key west so it is about 75-80 out every day and 100% humid

 

[olds97_lss]

How old is the engine? Has it sat for a long time without running (more than a few months)?

 

[skimbum686]

The engine is on the newer side never sat for more than a few weeks but i always use after run oil. I'm waiting to get more plugs so i can spend some time with it and try everything to get it to be tuned right and stay tuned