Remove LSN from carburator
 

Help, how can I remove the low speed needle from a OS .70-fsII carb?
As I back it out and the head of the lsn comes up it jams, same behaviour on both my OS70's.
(One brand new, other slightly used)

RE: Remove LSN from carburator
 

Take the barrel out of the carb first, the LSN then can be removed by
turning it all "in" till it drops out. It won't come "out" by trying to unscrew it. ;)

FBD. :D

RE: Remove LSN from carburator
 

Thanks a bunch!
I migt remove it and order a new screw, although this is a brand new engine, I have messed up the screw by not using the right screwdriver and when I tried to remove the lsn by unscrewing it I used mild force = screw head is a bit messed up.
I really hope I didn't damage the thread...!

RE: Remove LSN from carburator
 

http://www2.towerhobbies.com/cgi-bin...?&I=LXCP22&P=Z

Hopefully you can use this screw, because generally that part is not offered
for sale. That part doesn't wear out, nor is it likely to be damaged in a crash, or
ever need replacement. [:o]

FBD.

RE: Remove LSN from carburator
 

Before you buy, remove it and try to rework the screw slot. If that does not work contact me at [email protected] and I will take one off a old FS-70s carb I have.

Cheers,

Chip

RE: Remove LSN from carburator
 

Thanks for the generous support guys.

FBD, don't really understand what you mean? This is right on the money:
Parts Usage for O.S. Mixture Control Valve #70C Manufacturer Stock#45582300

This item is a part for the following:
LXXA42 O.S. FS-70 II Surpass
LXUS93 O.S. Carburetor #60P FS-91 Surpass II
LXCA49 O.S. Carburetor #60F .91 FX
LXWY29 O.S. Carburetor #60R FS-70 Surpass II
LXCA59 O.S. Carburetor #60N FS-91-P
LXCA61 O.S. Carburetor #70C


wcmorrison: I found a better fitting screwdriver and can now manouver the 'LSN', if I need a rerplacement in the future I buy the one listed above, couldn't accept yours and render your carb useless :o)

RE: Remove LSN from carburator
 

Folks, keep in mind the the Surpass I and the Surpass II engines have completely different carbs.

RE: Remove LSN from carburator
 

FBD:

Looks like you dropped yours and dinged it.

Bill.

RE: Remove LSN from carburator
 

William Robinson: That needle FBD shows is from the Towerhobbies product picture.
I have backed the lsn out 3 turns from bottom (carb fully closed) and will try the engine again tomorrow. If I can't get it to run I have to take the engine off the plane and investigate further.

Here's the deal:
Brand new engine, fired right up with factory settings and ran really good for two tanks of fuel for break-in.
When I refuelled the third time, mounted the wings and got ready to maiden the plane it was totally dead. Checked glow, plug, fuel etc... Seemed ok, but no go.
Then I decided to turn the lsn in to reset the stated "3 turns out" factory setting and I lost the lsn in the carb because I forgot to close the trottle barrel before turning the needle in.
As I said, I now have the needle out three turns and will give it another go tomorrow...

RE: Remove LSN from carburator
 

Tried the engine. No go :(
It seem not to get enough fuel somehow... If I prime it with my finger covering the muffler I can prime until it comes fuel out of the muffler, so it seem wet enough.
Then I try to crank it with electrical starter but no go. Tried LSN at 2.5turns - 3turns - 3.5turns.... HSN 3-3.5 turns

One question? Is the fourstroke supposed to push the fuel away from the carb at any time during a cycle?
When priming the engine I get fuel coming in the fuel line to the carb and after turning the prop another half turn it pushes fuel away again = fuel line is empty.
I can't keep fuel in the fuel line constantly while priming, it seem to surge back and forth as I rotate the prop.

RE: Remove LSN from carburator
 

Here's a way to get a preliminary setting on a low end screw when it is out
of whack. ( out of whack is a high tech term )

Close the barrel with a toothpick in it to keep it cracked open.
Put a length of fuel line on the carb inlet.
Blow through the fuel line and turn the screw in until the flow of air stops.
Open the screw until the flow of air starts again. (ccw)

That will give you a slight flow of fuel at the idle setting, and a good starting
point. From there, give it 1/8 turn at a time until you get it set. You can use
the "pinch test" to help get it set. Get the engine running at a fast idle, and
pinch the fuel line. If the engine speeds up, turn the screw "in" 1/8 turn and
try it again. If the engine just dies with out speeding up, it is too lean....open
the screw (counter clock-wise) 1/8 turn. You want it to speed up ever so
slightly when you pinch it (slightly rich).

A slightly rich setting on the low-end makes the engine easy to start, and
insures the engine will not over heat at low speeds from the setting being
too lean. Slightly rich is where you want the high speed needle to be as well.
Close the high speed needle until the engine is running as fast as it will go....
then open the needle until you hear the engine slow down a bit. That is the
slightly rich setting on the top-end.

FBD. ;)

RE: Remove LSN from carburator
 

I know how to tune the lsn once the engine is running.
The strange thing here is that the engine started and ran really nice for two tanks of fuel and after that it's impossible to start it.
(Tried with same settings as when it started and ran, also tried factory setting + - 1 turn)
I will take the engine off the plane and check the carb and plumbing out.

RE: Remove LSN from carburator
 

It is not uncommon for a small sliver of plastic from the tank, or other debris
to find it's way into the carb shortly after the engine is started. A fuel filter
will keep the carb clean. ;)

FBD. :D

RE: Remove LSN from carburator
 

FBD, I have updated my [link=http://www.rcuniverse.com/forum/m_3540270/anchors_3666985/mpage_2/key_/anchor/tm.htm#3666985]Build thread[/link]

RE: Remove LSN from carburator
 

I just read it, the plane looks good, and I like the engine. The fuse does look
narrow. [X(]

The "cold weather" Guys say to prime the engine with lighter fluid to get it
started in cold weather.

FBD. ;)