Re: needle setting OS15FP max rc

Surfer_kris Wed Aug 06, 2014 1:35 am

pkrankow wrote:
I have never actually needed to adjust an airbleed, or the low speed needle on a properly functioning carb. Since I didn't need to mess, I took the advice to leave it alone too. OS uses screwdriver heads for air bleed and low speed, meaning they expect most people to just leave it alone!

Quite the contrary, the screws are there to be adjusted, otherwise they could just have kept the fixed airbleed function they had on the OS .10FSR.

You set the airbleed screw for a good throttle respons, this is typically a little richer than what gives you the highest rpm for a given throttle opening. The airbleed hole is closed off around half throttle (by the throttle barrel), so therefore one sets the high-end (main needle) first, at full throttle. Then play with the airbleed screw. Small changes is weather etc, usually only requires small tweaks on the main needle, while the airbleed needs to be tweaked if one changes fuel or glowplug etc.

getback Fri Aug 08, 2014 7:50 pm

OK this is short because it takes forever to uploaddddddddd .... I put a spinner on it because yesterday tried to prop it over and got it really flooded ?????? should I be plugging the other of two vents so I have full pressure at the tank or leave one open ? it started and ran great , restart was good with plug on , I love the way it runs did not get tach. out till second run and noticed my mount screws were coming loose so had to stop prematurely , its oiled and put away for now awaiting a home!!! Thanks for all your Help guys, Very Happy

Eric

**RknRusty** Fri Aug 08, 2014 9:07 pm

getback wrote:...should I be plugging the other of two vents so I have full pressure at the tank or leave one open ? it started and ran great , restart was good with plug on ...

You have two pipes coming out of the tank. Is there another that I can't see? Out to the engine, and in from the muffler. I'm not sure what you're asking. If there is a third, it should only be opened for venting during fueling.
It runs good.
Rusty

pkrankow Fri Aug 08, 2014 10:59 pm

Very nice! I think you got it there.

Pressure doesn't work properly unless all lines are accounted for or plugged.

Exhaust into tank (some people put a filter here too!)
Feed into engine.
any added lines get plugged.

There are arrangements that use more than 3 lines, try to avoid them unless you really know why you want to use one of these arrangements (topping tank on acrobatic airplanes, topping tank on helicopters, multiple fuel tanks for 1 engine, multiple engines for 1 fuel tank...)

Most models can be done with 2 lines, with the fill through the fuel feed line. A fixed vent is needed so a clunk uniflow vent with a clunk fuel pickup is really the only time 3 lines are _necessary_.

Disconnect on the tank side of the filter if you are using one. Otherwise whatever was in the fresh fuel is concentrated and pushed into the spray bar immediately, which will have potentially disastrous results.

Phil

getback Sat Aug 09, 2014 8:05 am

Rusty ; yes it is a three pipe set up/ and Phil that was were I went wrong the first run I refueled the tank with the other vent line closed and flooded the crap out of it . I have some other tanks with just a two line setup and need to fix a better test stand . Been awhile since I ran an rc engine on pressure Embarassed

Thanks for helping me remember anything I forgot lol!

she really is a good runner and I picked it up cheap I think 20.00 Getback Very Happy

**RknRusty** Sat Aug 09, 2014 8:47 am

pkrankow wrote:Most models can be done with 2 lines, with the fill through the fuel feed line.

Right, and for a three line uniflow, fill through the pressure line. My setup will siphon back out if I don't clamp the pressure line until I'm ready to crank, so I have a clip on that line. It'll make you cuss if you filled your plane and then when it's your turn to fly, there is a 3 ounce puddle of fuel under the muffler.
Rusty

pkrankow Sat Aug 09, 2014 10:25 am

RknRusty wrote:
pkrankow wrote:Most models can be done with 2 lines, with the fill through the fuel feed line.
Right, and for a three line uniflow, fill through the pressure line. My setup will siphon back out if I don't clamp the pressure line until I'm ready to crank, so I have a clip on that line. It'll make you cuss if you filled your plane and then when it's your turn to fly, there is a 3 ounce puddle of fuel under the muffler.
Rusty

And I just learned something else that may make me cuss!

Phil

getback Sat Aug 09, 2014 11:30 am

Thanks , Rusty , I am yet to find any plastic hemi- stats , I put fuel hose on the metal one I have and while I am asking where did you get that bigger than 1/2a size syringe? I hate the old bubble fill apparatuses they just don't last long at all Sad

Thanks Eric

Surfer_kris Sat Aug 09, 2014 2:48 pm

It should run even better when you close the third line and get some pressure in the tank. Brodak has some larger syringes...

**RknRusty** Sat Aug 09, 2014 4:40 pm

Eric, PM me your address and I'll send you some plastic hemostats.
I get the syringes on e-bay. Search for 90ml or 90cc, or 3oz Luer Lock syringe. They're cheap, a buck or two each. Cover the numbers with clear packing tape and they'll stay on.
Rusty

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