OS 120FS surpass w/pump problem
shifflhl
first pumped 120's, not the II or III. The problem I'm having is that
it wants to run lean at top end and very rich at low end. I have backed
the hi speed needle out 'til it's almost falling out, and it still runs
very lean. I'm assuming lean as there is no smoke coming from the
exhaust and no oil output at all. At low speed it smokes and spits a lot
of oil. At the hi speed it has no oil output at all. I have experience
with the Saito 120's and this OS is driving me crazy. I have taken the
carb apart and checked to see there are no obstructions. It's the C12
carb. I've heard that the Hi needle is very sensitive to adjustments,
but to turn it out 8-10 turns with no noticable results is weird. I've
bypassed the pump (filling the pump with light oil, and connecting the
lines to keep from damaging the pump gears) and it's the same. I even
tried Clarence Lees fix with T's in the lines for the newer Surpass
pumped 120's same results. I have the FS glow plug in it, and the valves
are adjusted per instructions. The engine is new and only has about 20
oz of (BYRONS 10 %) fuel run thru it. Any suggestions out there.
Richard D.
same problem with the 46FX, rich at idle and lean at full throttle with over
heating. We found out that we where not getting enough pressure in the fuel
tank and the other problem is with the low end mixture/air adjustment screw,
it was set to lean so to compensate we where backing out the top end
adjustment screw 8 - 10 turns and we still could not get the engines to four
cycle, this is a two cycle engine. When the idle mixture/air adjustment
screw was backed out, richer, the problem went away almost, still had to
pressurize the tank but with the pump you should not be having this problem
so I'm just thinking it might be the idle mixture/air adjustment screw in to
far.
Hope this helps.
Richard D.
Former Airline Mechanics Credo:
We the willing
Led by the ungrateful!!!
Have been doing the impossible
For so long
With so little
That we are now qualified
To do anything
With nothing at all...
Werner Klotsche
I had such a Problem with the Surpass II. The reason was the Pump. It wasn´t
working anymore.
Put the tank on a long tupe, rise and lower at full speed. If the engine
reacts on the tanklevel, it is the pump.
If nothing happens, search for dirt or deribs in the fuelline. Perhaps the
fuelline in the carb itself is blocked. Put a tube on the carb and blow thru
at open needle.
The last reason the pump delivers not enough fuel at full throttle? Put a
little tank between pump and carb and squeeze it at full throttle, when the
engine get rich, You know it.
don´t worry, be happy
Werner
Pat Meredith
one thing is clear.
Insufficient fuel supply at the top end.
Fuel lines too small a bore?
Fuel tank too low inrelation to needle valve?
Fuel line too long?
Not enough back pressure from muffler?
Fuel line nipped by sharp bend?
Pressure line punctured?
Clunk too smaller bore?
Clunk not jammed against back of tank?
Clunk pick up tube too smaller bore?
Got the correct needle valve ?
I don't know why, but two types available for
OS120 carbs, one has a long taper which gives fine
adjustments, the other as a shorter taper less
precise adjustment but allows more fuel through.
But all the indicators are that you have insufficent fuel at
full throttle and the backed off needle valve is allowing
too much fuel through at low revs.
Pat Meredith NZ
"shifflhl" <shif...@jmu.edu> wrote in message
news:3CB25A20...@jmu.edu...
reply to
error in some of these pumps and one side of the seat is non existant so the
pressure does not develop and creates this lean running situation...
Conversely if your engine suffer from richness the cause can generally be
tracen to a bit of crud under the white nylon poppet valve, the fix here is to
replace this valve with the soft silicon one from a YS 1.20AC's regulator
Mike Chipchase
In article <3CB25A20...@jmu.edu>, shif...@jmu.edu says...