I am getting a ST 90 converted to ch igninton and a gas carb. The crank and rod are stock. The TT 120 on this http://tech.flygsw.org/ttpro120conversion.htm page is running on 16:1 ratio which is 8 ounces to 1 gallon of gas. Does anyone know who did this conversion.

Is this enough oil for a gas conversion with stock bushed rod ends?

If iam not mistacken I beleive this engine blew up after 40 flights I will look and see if I can find the article on it. But it could have been a different one.

Plenty of oil, 6.5oz/gallon would bring you into closer to 20:1 which I think is ideal.

Bill

With a stock rod on that small of an engine 10:1 mix (12 oz per gal)

That's enough oil for sure.

Bill

I just purchased a converted homelite 24 cc. The seller recommended a 32 to 1 ratio. I forgot what the ' 1 " was?? Is it outboard motor oil or what? Does 32 to 1 sound reasonable? thanks Rich

I will try 10:1 or 12:1 . Have any of you run these enignes like this? How bad is carbon build up running high oil content?

10:1 (10% high quality oil) would be my guess as well with bronze bearings.

edit:
more oil not necessarily means more carbon. Lean oil and fuel settings are much worse! With plenty of oil, and the correct carb adjustment (not rich, not lean), carbon formation will be minimal if a good modern synthetic two stroke blend is used.

deleted.

Jack

Whcih is better to use heavy weight like 50 weight motor oil or regular 2 cycle oil?

32:1 is safe 5.5 - 6oz per gallon (128 oz) is where I like to be - 20:1 or 21:1. Any good quality brand name two cycle oil will be fine. Twenty (20) parts fuel to one (1) part oil.

Bill

Two cycle which is, I think, straight 30 weight. I'm not sure what effect muti viscosity oil would have. heck, in the 50s and 60s we would just use 30 weight engine oil in our outboards.

Bill

Bill

Use 30 weight oil if synthetic, and 40 - 50 weight in mineral oils. Synthetics have a much higher wedge film strength, and that is why they are called "light running" oils.
Do not listen to, or try to compare the two stroke with the 4-stroke, nor use outboards with needle bearings as example. This thread is about a plain bushed conrod bearings in a small two stroke engine. The smaller the engine, the larger it's craving for oil, because less fuel passes through. With less fuel, also less oil is provided.

Pe,

So the motor oil is a better oil than plain outboard 2 cycle oil for my purpose? Will the synthetic motor oil blend with gasoline?