Richard,
The only possible problem a seriously cool running engine could create
would be water condensation in the oil. This manifests itself as a white
emulsified scum deposited on the insides of the rocker-boxes and in the
oil tank. Left un-corrected, this could cause bearing and piston wear. I
would not think this would cause a modern plug to whisker.
The wrong heat-range plug could in extremis. They should all look
whitish to light brown. Check that you are using the correct plugs and
if "yes", then I suspect that your problem is related to carburetion.
A rich mixture will cause the engine to run cool and the plugs to soot
up and misfire occasionally -- exactly the symptoms you describe. A
number of things could cause this.
If you have always suffered from sooty plugs, it could be that your
needles are set too high. If you regularly operate in a hot or high
terrain, the lower density air will cause the mixture to go over-rich.
The constant velocity carburettors will naturally compensate for this to
some degree, but the coarse adjustment is made by the needle position.
You might need to drop the needles one notch (Check your Rotax manual if
you are unsure how to do this).
Are all the plugs black or just those on one side of the engine?
If the problem only affects the plugs on one side, then you could have a
problem with the carburettor on that side.Remove the float bowl and
check for:
Floats not punctured
Float height set correctly (arm should be parallel with base of carb)
Needles seating properly and Viton tip not damaged
No detritus on needle seat.
Gasket sealing properly (look for signs of leaking -- light brown fuel
deposits around the gasket line)
If the symptoms have only recently started and all the plugs are
"sooty", then you may need to look at the air filter. Check that it is
not dirty or wet.
Also check that the float bowl vent pipes are not blocked and both
connect to the airbox plenum, the float bowl needs to operate at the
same pressure as the "filter" side of the carburettor and if it become
blocked or disconnected, the differential pressure will cause the
mixture to change.
Bit of a long answer, but the secret is to analyse how the problem began
and use a process of elimination to point to the cause.
Lastly, if you do need to get hold of some Bing carburettor spares, let
me know and I will put you in touch with an authorised Bing dealership
that sells spares at sensible prices -- not the kings ransom that Rotax
charge.
Nigel
On 16/06/2013 13:40, Richard Lamprey wrote:
>
> Greetings to all from Kenya.
>
> Does anyone know what is the minimum cylinder head (coolant) temperature for
normal operations? The manual gives maximum but no minimum, save for warming
up to above 50C for takeoff power. I was told recently that cylinder head temp
should not be too much below Oil temp, but not sure about this.
>
> Some years ago I had new radiators made by Docking Engineering of Silverstone,
after a leak in the Europa ones. They have proved so efficient that I cannot
get the temp much above 105C after prolonged climb, and it settles to 80-90C
in the cruise, against an oil temp of 105C. I put blanking strips on them to
get the temp a bit higher, to 95C, but took these off to test recently, and down
the temp went. The plugs are fouling up with carbon more now (with the odd
missed beat), which according to the manual is caused by running too cool.
But I cant find that optimum operating temperature stated anywhere. Any ideas
appreciated.
>
> A very simple Europa... 912UL, warp-drive fixed pitch.
> Best
> Richard
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=402782#402782
>
>
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