Temperature range for an OS 120 4 stroke
Greg Wright
toys to play with including a 9303 2.4 ghz radio with a bunch of JR
receivers to match. So I have been busy lately changing and re-
programming heli's & planes with the new receivers.
Here's where I need some help, I have a new funtana 125 I almost have
done and I put a new OS 120 4 stroke in it. I know that temperature
ranges can vary greatly but I was wondering if any one can give me
some ranges to try to stary within. I plan on breaking it in on the
ground at the house for a few tanks and know that the exit opening of
the cowl is very important for cooling but won't be a factor until
it's in the air of course.
I just want to make sure I have the engine all tuned in and steady so
I don't have dead stick issues with a brand new plane. Any advice on
this or "do's & don'ts" of 2.4 ghz would be helpful. I was hoping to
make the maiden voyage on January 1st, but it just didn't work out
that way.
Thansk guys for your advice.......Greg
Bob Richards
Greg,
I ran an OS 1.20 Surpass II for a few years in pattern planes. I'll bet I burned 100 gallons in three years with a couple of OS 1.20s. Don't know if the current OS 1.20 is the same or not.
The Surpass II had a gear pump and a special pump carb. With 10% nitro fuel, you could not set the idle mixture lean enough. 15% would work, but I had the best luck with 20-25% nitro. (more nitro requires richer settings). Also, with the lower nitro fuels, if the top end was too rich, it would load up in transition and would not smooth out until the hs needle was leaned out. For some reason, trying to adjust the hs needle on the rich side did not work well with this engine. Again, the higher nitro fuel made the setting much less sensitive.
All my experience with 4S engines taught me many things. For one, never EVER use four-stroke fuel (low nitro, low oil). Idle and transition will be better with 15% minimum nitro 2S fuel, or 20-20 "YS" fuel. Use an OS 4S plug. Powermaster has a 20-20 blend that works great. I think East RC may carry that.
I have no idea at what temps it ran - never checked. Never felt the need. Of course, this was back in the early 90s before IR temp guns were cheap.
Use a really good glow driver. I use a Radio South driver. I could start my inverted OS in cold weather easily with that.
I would never use a wood prop on it. You need to tighten the prop nut very tight to keep it from coming loose, and wood props compress too much. The APC props were all that I used, since they weigh more than wood props there is more flywheel effect which helps the idle.
For the Funtana, I would start with a 15x8 prop. If you want to 3D and hover, a 16x6 might be better. I'll try to remember to check my stock, I might still have a 15x8 somewhere.
Good luck,
Bob R.
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Greg Wright
forgot to mention that I was going to use cool power 15% synthetic
(which I believe is 18% oil content, which I buy from East R/C) and I
am using the OS "F" plug in it. (Came with the engine) It does not
have a pump on it so it should be standard settings on both the high
and low end needle valves.
APC props for sure, better performance in my experience. So it sounds
like I am on the same page with you, I appreciate you sharing your
experience!!!
On Jan 2, 8:15 pm, Bob Richards <b...@toprudder.com> wrote:
> Greg,
>
> I ran an OS 1.20 Surpass II for a few years in pattern planes. I'll bet I burned 100 gallons in three years with a couple of OS 1.20s. Don't know if the current OS 1.20 is the same or not.
>
> The Surpass II had a gear pump and a special pump carb. With 10% nitro fuel, you could not set the idle mixture lean enough. 15% would work, but I had the best luck with 20-25% nitro. (more nitro requires richer settings). Also, with the lower nitro fuels, if the top end was too rich, it would load up in transition and would not smooth out until the hs needle was leaned out. For some reason, trying to adjust the hs needle on the rich side did not work well with this engine. Again, the higher nitro fuel made the setting much less sensitive.
>
> All my experience with 4S engines taught me many things. For one, never EVER use four-stroke fuel (low nitro, low oil). Idle and transition will be better with 15% minimum nitro 2S fuel, or 20-20 "YS" fuel. Use an OS 4S plug. Powermaster has a 20-20 blend that works great. I think East RC may carry that.
>
> I have no idea at what temps it ran - never checked. Never felt the need. Of course, this was back in the early 90s before IR temp guns were cheap.
>
> Use a really good glow driver. I use a Radio South driver. I could start my inverted OS in cold weather easily with that.
>
> I would never use a wood prop on it. You need to tighten the prop nut very tight to keep it from coming loose, and wood props compress too much. The APC props were all that I used, since they weigh more than wood props there is more flywheel effect which helps the idle.
>
> For the Funtana, I would start with a 15x8 prop. If you want to 3D and hover, a 16x6 might be better. I'll try to remember to check my stock, I might still have a 15x8 somewhere.
>
> Good luck,
>
> Bob R.
>
> --- On Sat, 1/2/10, Greg Wright <harle...@nc.rr.com> wrote:
Bob Richards
Without the pump, the needle will be a little less tempermental. Cool Power will be fine. I burned a bunch of that myself.
Good luck.
Bob R |