I am going to perform more tuning on my engine and I wanted to know what is a safe operating temp.

How hot is too hot??

Engine:
Ryobi 31cc
18x8 wood prop

If your used to glow, You'll find the gassers run a bit hotter (it seems) than glow engines.
You won't overheat with an 18x8. I've found that's the best size prop to run on my twin-ring ryobis.

The bigger concern for these motors is under propping and excceding max RPMs of about 9000 with the stamped steel con-rod.
(which you won't do with that prop)

One nice thing about the heat though...with the right muffler.......they SURE DO MAKE NICE SMOKE!!!

Sorry I don't have temps, but I'd like to see some readings on other people's temps too...

CrazyHerb

Just as an offhand guess for cylinder head temp, I want to say 400 degrees max, 350 good, 300 great! EGT temps would be around 1200 max, 1100 better. Just an educated guess you understand, but it should be close.

Good luck,
AV8TOR

This is all good to know--!

I think I have been running a bit rich which has caused my inverted engine to sputter under G's. It almost seem like the spark plug is getting fowled by excess fuel? In any case the problem gets more aggravated when I richen it up and seems to disappear when I lean it out.

But I am afraid of getting to lean so I want to monitor the engine temp. My engine seems to peak at about 7200 rpm when I back it down 200 the problem is bad enough that I don't like the way it flies- Curiously at mid range it runs great (no G' choking)

Still- I prefer this gas engine to my OS 1.20. Soooo much cheaper.......

Hi,

The gas engines are not nearly as critical about lean running as the glow engines, and do not like to be run real rich. You don't want to hear a reassuring occasional rich burble like is ok on a glow engine. It usually works best to adjust for peak rpms, and then just open the needle 1/8 turn or less. If you adjust it too rich, it will eventually carbon up, freeze the rings in their grooves and seize. You will sometimes notice a kind of a burble if/when the engine unloads in a dive; this is normal.

Have fun,
AV8TOR

Best way to set the carb is to read the plug. Best is a tan brown colour. Dark brown or black, is to rich. Light tan or white is to lean.

This is true, but you have to get close first. You also have to run the engine for a few minutes at full throttle, then shut it off without letting it idle. Then the plug insulator will be tan to chocolate brown if the mixture is right, and the outer shell will be black with no increasing deposits.

AV8TOR

Update-----

My operating temps are:
Outside temp= 50 Degrees
Idle= 180-200 @ 1700-2000 rpm
Full throttle= 300-350 @ 7000 rpm.

This is with a 18x6 prop and the engine fully cowled- Later I will try this same test without the cowl to see what the difference is.