Trick Question....

[Massimo]

More advice needed please....

All of a sudden i have lost approx 400rpm on my motor
Yes i flew 2 weeks back in the morning and had the usual 6400 max rpm and that afternoon only had 6000 max rpm.... and thats all ever since.

Ive now repalced spark plugs, cleaned air filter, changed fuel filter, cleaned jets but still no revs....

Motor runs very well, no misses etc, just no revs.

WHERE are they hidding................

Please do not tell me to re-pitch my prop as i did not touch the prop in the first place That is not solving the problem.

HELP, my lift capacity with pax has gone for a ball of

[Bacardi]

In my book this is indicative of progressive carbon build-up, sticky rings and some blow-by starting. A friend had the same symptoms which were duly reversed by pomping a can of Wynn's Compression Stabiliser through the carbs and into pots. Try this for starters, else go the manual de-coke way.

[Massimo]

Was manually de-coked in december

[vliegvark]

check the tips of the prop if there are any tape on the tips they might be loose and that can give you the problem , I had the same problem on my old 582
and then if thats not the problem inspect your rings they must be loose on the piston but if it's not getting worse then I would say check leading edge the prop ever some nicks can make the revs go down

[skybound®]

Also check your RPM gauge and wiring. Perhaps no missing RPMs but a poor signal or a rev counter that is not counting as it used to

[Duck Rogers]

Ai ja jai.... the causes COULD be any of the following
This is tricky

a)Scored piston and/or cylinder
b)Leaking head gasket
c)Blocked exhaust (check for rattling inside...possibly some part of the baffle has broken/rusted off inside
d)Worn out needle jet (EGT will tell you about this though)
e)Dirt in the carburettor
f)Dirt in the needle valve
g)Loose or leaking carburettor (EGT will be high)
h)Faulty fuel pump......not operating at the correct pressure
i)Ignition cable problem. Maybe loose or badly insulated
j)Spark plug connector faulty
k)Spark plug ignition cable faulty
l)Piston ring/s stuck (yes I know.........December)
m)Float level too high
n)Mag faulty
o)Mag cable faulty
p)Check the prop carefully.......if adjustable, check pitch settings to be the same
q)Skybound's answer is not far fetched at all! Very possible.

and finally........if I was to place a bet, I'd be siding with Bacardi on this one. (nevermind December) :D

[RV4ker (RIP)]

Not maybe
Load Shedding

[Thatchman]

Massimo, if all else fails, ask softness to lose some weight

[Morph]

Was manually de-coked in december

Check the torque on your cyl head bolts. They might mave started to work loose

Did the rpm's drop since the motor has been put back together or did it run fine after reassembly and then suddenly drop 400rpm

[Duck Rogers]

Did the rpm's drop since the motor has been put back together or did it run fine after reassembly and then suddenly drop 400rpm

It seems it ran ok after reassembly and then dropped 400 rpm. At least that's what I understand from the original post.......hence all the options for a possible cause

[Massimo]

Yes ran ok after re-assembly. THen flew a saturday morning and all ok and that same afternoon 400 rpm less.
Will try carb clean as soon as i can get to the field.

[Low Level]

Check throttle cables, play and 100% throttle opening.

My 2c

[Duck Rogers]

Check throttle cables, play and 100% throttle opening.

My 2c

Damn......! Now why didn't I think of that Quite logic too :D