OS C-Spec PS needle setting

[Frank Toorenburg]

I have trouble to set my Carb on my C-Spec PS. I have the mid needle.

I use: it in My Fury Tempest, MP2, CP-30%.

High needle 1 turn
Mid needle 1/2 turn.

Is this correct?, how are your needle set???

[DavidH]

OK by your post I am guessing that you have added the 3rd needle to the carb where the check valve is located for the mid range.
When I was using the PS motor with CP 30% and the third needle.
I ran the
main needle about 1 1/4 open from fully closed
mid range needle 1 1/2 open from fully closed plus 3 clicks.
low speed needle just slightly off center position towards the rich setting.

The third needle ( mid range) on the PS does not work like a normal needle.
Closing the needle richens up the mid range, opening the needle leans it out.
When the needle is closed it is not allowing as much fuel to bypass thru the check valve, when it is open it is allowing more fuel to bypass the midrange.

David

[Frank Toorenburg]

Thank you David, I will try this setting.

/Frank

[sumonzu]

OK by your post I am guessing that you have added the 3rd needle to the carb where the check valve is located for the mid range.
When I was using the PS motor with CP 30% and the third needle.
I ran the
main needle about 1 1/4 open from fully closed
mid range needle 1 1/2 open from fully closed plus 3 clicks.
low speed needle just slightly off center position towards the rich setting.

The third needle ( mid range) on the PS does not work like a normal needle.
Closing the needle richens up the mid range, opening the needle leans it out.
When the needle is closed it is not allowing as much fuel to bypass thru the check valve, when it is open it is allowing more fuel to bypass the midrange.

David

Hi David,

I'm going to put a 3 needles carb on my OS 91 PS, but I do not know how to connect all the lines. For instance where to insert the check valve?
Can you post a crear photo or a draw?
Thank you!
Marcello

[DavidH]

Marcello,
Nothing changes on the carb or the plumbing of the lines.
All you do is take the brass looking fitting out of the carb where the check valve is located. Then you screw the new needle assembly into the carb. The check valve and all the lines stay just like they were before you added the needle.

I don't have a picture of the carb ( 60M) with the third needle installed. Maybe someone here has one.

David

[Robert Johns]

David,

Here is a pic of the 3rd needle installed in a PS with a 60M carb.

-robert

[Robert Johns]

Here is another pic showing the installation for those who are interested in going this route.

-robert

[marked23]

I presume that the 60M is the stock 91csps carb... Is that correct?

So this third needle for the 60M. What is that part number and who sells it?

If my engine is running good right now, without the third needle, will having this third needle improve anything? What I'm seeing is that for my current settings, there is a very fine line between sloppy rich and twitchy lean. I can find the sweet spot in a few clicks.

-Mark

[Robert Johns]

Mark,

The 60M is the stock carb on the PS. Rick's sells the extra needle (# OSMG0165).

If your setup is working without issues then you have a good PS and I wouldn't make any changes. If you are having issues with the mid-range leaning out and/or you just want to experiment, you can add the third needle - it can make it easier to tune and control the midrange. Just remember that this needle is adjusted opposite from a regular needle - clockwise richens the midrange and counter-clockwise leans it.

-robert

[sumonzu]

David,

Here is a pic of the 3rd needle installed in a PS with a 60M carb.

-robert

Thank you very much for the photo. I'd like to know if you have resolved all the midrange issues with this third needle. I've not added the third needle yet and when the full throttle is right I'm havin the engine running lean at middle range: I suppose this is the issue most of us has had.
Also I'm very cuirious to know if the modified OMI 60K carb works better that the original 60M with the third needle installed. Did anyone has experimented both solutions?
Thank you
Marcello

[DavidH]

Marcello,
Yes the third needle will help with the mid range adjustment.
I have ran both the 60 M carb and the OMI 60K carb.
My motors now have the OMI 60K carb with Cline installed.

I personally prefer the 60K carb with Cline over the 60M carb and pump system.

David

[wattybotts]

I was readin this whole thread and got to wondering....

This past weekend at a Fun Fly, on Friday, I couldnt tune my PS worth a darn. I had to go back to the stock needle settings. I got it tuned fine, but my mid range (the return needle) is screwed all the way in. I know this cant be right, but the motor is making plenty of power and not leaning out anywhere. Do I have a bad pump? Or do I need to fiddle with the screw on the bottom of the pump?

Thanks
Bobby