Rovan 1/5 Baja 5B - Getting Started

[PaulFWI]

I've got the car now. I apologize for asking these newbie questions but I want more/current opinions:

- What is the best premix ratio to use *for this engine*? (This is the 30.5cc.) I read everything from 25:1 to 50:1.

- I really want to avoid flooding on the first start. Is the best procedure as in their video, to prime until there is fuel moving, then choke on, pull till it pops, choke off?

- The manual for the TX (FS-GT3B) is clearly not the correct one - and the online manual is the same. Both specify 4 AA batts while it requires 8. This is not a big deal but I find it extremely strange. Any comments?

 

[Tunedfrog]

Your first start probably won't flood. I did 4 or 5 tanks for the heat cycle break in and always used the supplied fuel mixture bottle that came with the kit.
I mix it equal parts oil and gas. The can is set up for mixing choices.
I know it's not the most accurate way to do it but for me, I just watch for a little smoke and tells me the engine is getting enough lube. and then lean it out a tiny bit for fine tuning.

 

[Grizz03]

Your first start probably won't flood. I did 4 or 5 tanks for the heat cycle break in and always used the supplied fuel mixture bottle that came with the kit.
I mix it equal parts oil and gas.
I know it's not the most accurate way to do it but for me, I just watch for a little smoke and tells me the engine is getting enough lube. and then lean it out a tiny bit for fine tuning.

Are you saying you run 1:1 ratio? I hope that's a mistake because that's unheard of.

 

[Tunedfrog]

No I'm not, the Rovan fuel can has two areas, one for the gas and the handle is a oil section. If you pour the oil in at the same level as the gas is, that will give you the correct mixture but off the top of my head, I don't remember what it is.
The oil side is a lot smaller than the gas side. So I see where you got confused. .
Tip the can with the lid on and you well see the oil drain into the gas side. It's mixed that way.
I tried to post a pic of the can but of some reason it won't let me.
Again, it's not the most accurate but my eye sight isn't what is used to be and I can see this better than trying to read the little numbers.

 

[Grizz03]

No I'm not, the Rovan fuel can has two areas, one for the gas and the handle is a oil section. If you pour the oil in at the same level as the gas is, that will give you the correct mixture but off the top of my head, I don't remember what it is.
The oil side is a lot smaller than the gas side. So I see where you got confused. .
Tip the can with the lid on and you well see the oil drain into the gas side. It's mixed that way.
I tried to post a pic of the can but of some reason it won't let me.
Again, it's not the most accurate but my eye sight isn't what is used to be and I can see this better than trying to read the little numbers.

Yes you are. You're confused as to what oil/fuel mixture is.
Using the measuring can like you are describing is different than a 1:1 ratio. 1:1 ratio would be 1/2gal of oil to 1/2gal of gas for a 1gallon mixed.

When describing oil fuel ratio it is about how many equal parts.

 

[Tunedfrog]

Exactly and no I'm not confused, I explained it the best I could without a pic of the can so OP would know what I am talking about.
I said absolutely nothing about mixing 1:1. Nor did I give you the definition of what oil/fuel mixture was.
The OP asked and I simply told him what I use.
This is what I use. the green cap on the right is the oil side. it's a lot smaller than the left side. When you put them level it gives you a fuel mixtured. What exactly that mixure is I have no clue, I don't remember. you can use less oil on the right and more fuel on the fuel side, it is marked as to what mixture it is.
I mixed it level on both sides because I can't see the lines that show me what the mixtures are.

Fuel mixture can.

 

[Grizz03]

You did! That's why I asked for clarification.
What does equal parts mean?

...
I mix it equal parts oil and gas...

The OP was also asking about 25:1 and 50:1 which is a ratio and which one to use.

 

[Tunedfrog]

You did! That's why I asked for clarification.
What does equal parts mean?

My bad, fill them to the same line. Look at the link and you will see what I'm talking about.
Mistake on my part as far as writing it but rest assured, I'm not confused.
If you would have read the part of my post that I stated the oil side is a lot smaller than the gas side. You could have figured that out.
We are done here.

 

[Grizz03]

And I will agree. Those type of premix containers are a lot easier than measuring out each individually.
But they are only an easy way of making a pre-set fuel oil ratio. And NOT what different fuel ratios are.

...
- What is the best premix ratio to use *for this engine*? (This is the 30.5cc.) I read everything from 25:1 to 50:1.
...

I believe Rovan specifies 25:1

 

[Tunedfrog]

@PaulFWI , my bad, I didn't mean equal parts gas and oil, I meant to say fill to the same line if using a rovan mixing can.
I'll apologize to you though.

 

[Chubaka]

I'm just gonna add ethanol free gas will save you in the long run.

 

[tntpoof]

the ratio is whatever the engine manual says.....

 

[PaulFWI]

I was looking for real-world data points. I know what the manual says. And I have a great deal of experience with premix-using two-stroke gasoline engines in general - I raced motocross for ten years (before those horrid 4-strokes were mandated) and later in life flew full-scale light-sport aircraft with Rotax engines (503 and 582).

I want to know the ideal gasil ratio for these engines in particular. I suspect that 25:1 is not necessary - that is a LOT of oil and I've never run a ratio so high on any engine I can think of. 40:1 is more common.

I think I'll start with 32:1 and see how it goes. I don't want fouled plugs.

 

[Grizz03]

I don't know why the ratio is so high myself either. I don't have a zenoah rc but like you have experience with 2-stroke engines. In the past I ran the richer oil ratios in my small engine weed wacker/chainsaws/outboards up to my bigger sled engines and had that build up of carbon. With today's better quality oils (I use Amsoil synthetic) I don't get that carbon build up. But I do run leaner oil ratios in addition to the better synthetic oil. I also run high octane ethanol free gasoline.
I know the manual calls for 25:1. I've also read where others have run 32:1 (or even 40:1) without any issues. I might run the heavier mix for the first gallon for break-in then switch. Just be sure to retune when changing ratios.

 

[cbaker65]

I got two of those cans ,they are pretty cool!

32 to 1 is the most common mix for all these low budget engines an a safe mix ,itis 4 oz's per Gal.!
When I ran my gardening equipment I shaved the oil back to 3 1/2 oz's because the oil would cake
up at the exhaust port & clog the spark restrictors in the muffler can ,but I remove all of the spark
resisters out of my equipment do to the 32 to 1 was just a little too much oil ,but that ratio is safe
for break-ins ,40 to 1 was about right for gardening equipment but I would feel safer at 32 to 1
for RC engines!