Hi guys I wonder if anybody could give me any ideas as to what could be wrong with my 503 dcdi,
Bought it new about 18 months ago...one of the last available...when I fitted it to my a/c I was not happy with the factory set carb needle position as the EGTs on both pots could be just over the 650c or 1200f Rotax limit,
I spoke to the Rotax dealer I bought it from and he said it should be fine...but I was not comfortable so I raised the needles one slot...this got both EGTs to a max of 625c 1160f,
I have been running it like this for the last 18months and its ran like a dream...until a month ago when I thought it had used a bit more fuel than normal and the EGT temps where down a bit...so I thought I would try re-setting it to factory spec again and lowered the needles one notch,
I then flight tested it again but was again uncomfortable with the higher EGTs in the cruise near 650c 1200f...so I went back to where they where,
I had a 2 hour flight yesterday on a very very warm day here in the UK 20c 70f and noticed it would not hold a steady RPM for long...I normally cruise at 5000rpm it would hold this but after a minute or so the RPM would start going up to around 6100rpm all by its self,
I then would close my hand throttle a small amount to get back to 5000rpm...moments later the rpm would drop to say around 4700rpm...I would adjust again for 5000rpm and things would be ok again for a short time and so on,
I did notice that my EGTs during this time where a bit lower than normal at around 580c 1080f,
I am wondering if the very hot day for us here in the UK could have been causing the mixture to become to rich and let the engine bog,
But I'm not to happy weakening the mix even though I'm on a richer setting than Rotax recommend,
I wonder if air-filters that get wet with 2 stroke can partly restrict the airflow causing a rich mix...as is the case with lots of 2 strokes mine does get damp with 2 stroke oil after use.
Nick in the UK.
Bought it new about 18 months ago...one of the last available...when I fitted it to my a/c I was not happy with the factory set carb needle position as the EGTs on both pots could be just over the 650c or 1200f Rotax limit,
I spoke to the Rotax dealer I bought it from and he said it should be fine...but I was not comfortable so I raised the needles one slot...this got both EGTs to a max of 625c 1160f,
I have been running it like this for the last 18months and its ran like a dream...until a month ago when I thought it had used a bit more fuel than normal and the EGT temps where down a bit...so I thought I would try re-setting it to factory spec again and lowered the needles one notch,
I then flight tested it again but was again uncomfortable with the higher EGTs in the cruise near 650c 1200f...so I went back to where they where,
I had a 2 hour flight yesterday on a very very warm day here in the UK 20c 70f and noticed it would not hold a steady RPM for long...I normally cruise at 5000rpm it would hold this but after a minute or so the RPM would start going up to around 6100rpm all by its self,
I then would close my hand throttle a small amount to get back to 5000rpm...moments later the rpm would drop to say around 4700rpm...I would adjust again for 5000rpm and things would be ok again for a short time and so on,
I did notice that my EGTs during this time where a bit lower than normal at around 580c 1080f,
I am wondering if the very hot day for us here in the UK could have been causing the mixture to become to rich and let the engine bog,
But I'm not to happy weakening the mix even though I'm on a richer setting than Rotax recommend,
I wonder if air-filters that get wet with 2 stroke can partly restrict the airflow causing a rich mix...as is the case with lots of 2 strokes mine does get damp with 2 stroke oil after use.
Nick in the UK.
