OS FS-91 Idle settings problem
01-24-2004, 09:01 PM
#1
Junior Member
Thread Starter
Join Date: Oct 2003
Location: Curitiba, BRAZIL
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
OS FS-91 Idle settings problem
Can someone help to solve the following problem?? I have bought a used OS FS-91 4-Stroke,
but it idle setting is not good. I can not get an idle under 3400 r.p.m. I have turned the
idle mixture screw clockwise almost to the end and the idle setting still seems to be rich.
On the other hand, I am able to get a very good high settings and the engine is not loosing
power.
Many Thanks - Yves Russo
[>:]
but it idle setting is not good. I can not get an idle under 3400 r.p.m. I have turned the
idle mixture screw clockwise almost to the end and the idle setting still seems to be rich.
On the other hand, I am able to get a very good high settings and the engine is not loosing
power.
Many Thanks - Yves Russo
[>:]
01-26-2004, 10:41 AM
#2
My Feedback: (11)
RE: OS FS-91 Idle settings problem
Check the valve/rocker arm clearances. Then "ball park" the carb per the instructions. If you don't have them, email us at the address below to get a set emailed back.
If the carb's set correctly, and the valve lash is correct, then the compression seal is starting to go. When an engine starts wearing out, idle and acceleration are the first things to go south.
If the carb's set correctly, and the valve lash is correct, then the compression seal is starting to go. When an engine starts wearing out, idle and acceleration are the first things to go south.
08-07-2005, 07:13 AM
#3
Junior Member
Join Date: Sep 2003
Location: Stow,
OH
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
RE: OS FS-91 Idle settings problem
I HAVE THE SAME PROBLEM WITH MY OLD FS-91 4-STROKE I BOUGHT USED, I JUST CAN NOT GET IT TO IDLE BETWEEN 2000 & 2500 R.P.M. AND I JUST CAN NOT GET IT TO DO A SMOOTH TRANSITION FROM IDLE TO HIGH R.P.M.
I BURNED A EXHAUST VALVE, WHICH I THINK WAS CAUSED BY A BROKEN VALVE SPRING.
I WENT AND REPLACED BOTH INTAKE & EXHAUST VALVE ASSEMBLIES, CYLINDER LINER, PISTON RING AND GASKET SET.
STILL CAN NOT GET THE ENGINE TO IDLE. IT SEEMS TO RUN BETTER FROM IDLE TO FULL POWER AND IDLE BETTER IF I LEAVE THE GLOW BATTERY ON. WHEN IT IS REMOVED I LOOSE THE SMOOTH TRANSITION FROM LOW TO HIGH POWER AND THE IDLE GETS RICH AND QUITS.
MY FUEL TANK IS ABOUT 1/4 IN. ABOVE THE CENTERLINE OF MY CARB CAN NOT GET IT TO LINE UP BECAUSE OF THE ENGINE CENTERLINE AND THE PLANE DESIGN.
I AM ABOUT TO GIVE UP AND JUST BUY A NEW ENGINE BUT AFTER READING YOUR REPLY, DO YOU THINK I NEED TO BUY A NEW CARB.?
I USED WILDCAT FUEL 10% NITRO 18% OIL, 15% NITRO 18% OIL AND YS 20% NITRO 20% OIL
PROP SIZE IS MASTER 14X6 AND PCP 15X4
I BURNED A EXHAUST VALVE, WHICH I THINK WAS CAUSED BY A BROKEN VALVE SPRING.
I WENT AND REPLACED BOTH INTAKE & EXHAUST VALVE ASSEMBLIES, CYLINDER LINER, PISTON RING AND GASKET SET.
STILL CAN NOT GET THE ENGINE TO IDLE. IT SEEMS TO RUN BETTER FROM IDLE TO FULL POWER AND IDLE BETTER IF I LEAVE THE GLOW BATTERY ON. WHEN IT IS REMOVED I LOOSE THE SMOOTH TRANSITION FROM LOW TO HIGH POWER AND THE IDLE GETS RICH AND QUITS.
MY FUEL TANK IS ABOUT 1/4 IN. ABOVE THE CENTERLINE OF MY CARB CAN NOT GET IT TO LINE UP BECAUSE OF THE ENGINE CENTERLINE AND THE PLANE DESIGN.
I AM ABOUT TO GIVE UP AND JUST BUY A NEW ENGINE BUT AFTER READING YOUR REPLY, DO YOU THINK I NEED TO BUY A NEW CARB.?
I USED WILDCAT FUEL 10% NITRO 18% OIL, 15% NITRO 18% OIL AND YS 20% NITRO 20% OIL
PROP SIZE IS MASTER 14X6 AND PCP 15X4
08-07-2005, 03:25 PM
#4
Junior Member
Join Date: Sep 2003
Location: Stow,
OH
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
RE: OS FS-91 Idle settings problem
I have the same problem i can not get my FS-91 Surpass to idle between 2000 & 2500 R.P.M. when i leave the glow battery on the idle is OK and the transition from idle to full power is great but when i remove the battery the engine's idle goes rich then quits.
the transition from idle to full power is rich and slow. i have changed the glow plug and tried to adjust the idle mix setting but what ever i do it runs the same way.
my fuel tank is about 1/4" above the centerline of the carb. i can not make it equal to centerline of carb. because of plane design.
the props i used is Master 14x6 and a 3D 15x4 fuel used is wildcat 10% nitro 18% oil, 15% nitro 18% oil and YS 20% nitro 20% oil.
i think maybe i could try a new carb. what do you think? I just replaced the cylinder liner, piston ring and both valve assemblies
because i burned the exhaust valve i think it was the broken valve spring that did it.
the transition from idle to full power is rich and slow. i have changed the glow plug and tried to adjust the idle mix setting but what ever i do it runs the same way.
my fuel tank is about 1/4" above the centerline of the carb. i can not make it equal to centerline of carb. because of plane design.
the props i used is Master 14x6 and a 3D 15x4 fuel used is wildcat 10% nitro 18% oil, 15% nitro 18% oil and YS 20% nitro 20% oil.
i think maybe i could try a new carb. what do you think? I just replaced the cylinder liner, piston ring and both valve assemblies
because i burned the exhaust valve i think it was the broken valve spring that did it.
08-08-2005, 06:19 AM
#5
Junior Member
Join Date: Sep 2003
Location: Stow,
OH
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
RE: OS FS-91 Idle settings problem
I HAVE THE SAME PROBLEM WITH MY OLD FS-91 4-STROKE I BOUGHT USED, I JUST CAN NOT GET IT TO IDLE BETWEEN 2000 & 2500 R.P.M. AND I JUST CAN NOT GET IT TO DO A SMOOTH TRANSITION FROM IDLE TO HIGH R.P.M.
I BURNED A EXHAUST VALVE, WHICH I THINK WAS CAUSED BY A BROKEN VALVE SPRING.
I WENT AND REPLACED BOTH INTAKE & EXHAUST VALVE ASSEMBLIES, CYLINDER LINER, PISTON RING AND GASKET SET.
STILL CAN NOT GET THE ENGINE TO IDLE. IT SEEMS TO RUN BETTER FROM IDLE TO FULL POWER AND IDLE BETTER IF I LEAVE THE GLOW BATTERY ON. WHEN IT IS REMOVED I LOOSE THE SMOOTH TRANSITION FROM LOW TO HIGH POWER AND THE IDLE GETS RICH AND QUITS.
MY FUEL TANK IS ABOUT 1/4 IN. ABOVE THE CENTERLINE OF MY CARB CAN NOT GET IT TO LINE UP BECAUSE OF THE ENGINE CENTERLINE AND THE PLANE DESIGN.
I AM ABOUT TO GIVE UP AND JUST BUY A NEW ENGINE BUT AFTER READING YOUR REPLY, DO YOU THINK I NEED TO BUY A NEW CARB.?
I USED WILDCAT FUEL 10% NITRO 18% OIL, 15% NITRO 18% OIL AND YS 20% NITRO 20% OIL
PROP SIZE IS MASTER 14X6 AND PCP 15X4
I BURNED A EXHAUST VALVE, WHICH I THINK WAS CAUSED BY A BROKEN VALVE SPRING.
I WENT AND REPLACED BOTH INTAKE & EXHAUST VALVE ASSEMBLIES, CYLINDER LINER, PISTON RING AND GASKET SET.
STILL CAN NOT GET THE ENGINE TO IDLE. IT SEEMS TO RUN BETTER FROM IDLE TO FULL POWER AND IDLE BETTER IF I LEAVE THE GLOW BATTERY ON. WHEN IT IS REMOVED I LOOSE THE SMOOTH TRANSITION FROM LOW TO HIGH POWER AND THE IDLE GETS RICH AND QUITS.
MY FUEL TANK IS ABOUT 1/4 IN. ABOVE THE CENTERLINE OF MY CARB CAN NOT GET IT TO LINE UP BECAUSE OF THE ENGINE CENTERLINE AND THE PLANE DESIGN.
I AM ABOUT TO GIVE UP AND JUST BUY A NEW ENGINE BUT AFTER READING YOUR REPLY, DO YOU THINK I NEED TO BUY A NEW CARB.?
I USED WILDCAT FUEL 10% NITRO 18% OIL, 15% NITRO 18% OIL AND YS 20% NITRO 20% OIL
PROP SIZE IS MASTER 14X6 AND PCP 15X4
