Rotax 503 engine lag

by Geoff Storey in 2 Stroke Technical Questions 13 years ago

Hi all my 503 starts fine runs up to full power but at around 3000 rpms it lags or misses if it sits around those revs and you push the throttle forward it drops revs misses then picks up back to normal
it also happens a 4300 rpms but not all the time. Not good when landing pull the power back to decend and need a bit of power to slow up the decent it takes a bit before any responce any suggestion what is happening .
Cheers Geoff...

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Re: Rotax 503 engine lag

by Nick Axworthy » 13 years ago

Nick Axworthy

16 325 0

Has it ever ran ok since you have owned it.

Nick.

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Re: Rotax 503 engine lag

by Geoff Storey » 13 years ago

Geoff Storey

7 33 0

Hi Nick not really since the rebuild it starts easy runs up full power all temps are great just got this weird lag not sure if is electrical or fuel.
cheers Geoff....

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Re: Rotax 503 engine lag

by Nick Axworthy » 13 years ago

Nick Axworthy

16 325 0

Mmmm you dont say what you re-built....I wonder if it was the carb...if so sounds like the needle could be mounted the wrong side of the plastic cup....or was it an engine re-build,

How did it run before the re-build ????

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Re: Rotax 503 engine lag

by Geoff Storey » 13 years ago

Geoff Storey

7 33 0

Hi again Nick this is the engine that grab a piston awhile ago it was running to lean you commented on the motor for me.
l changed barrels new piston and rings change crank and new seals put in a 50hr one l have for spares rebuilt both carbys needles are in the right side of the slid also new exhaust as the other one was cracked .

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Re: Rotax 503 engine lag

by Nick Axworthy » 13 years ago

Nick Axworthy

16 325 0

Sorry I remember now Geoff....wow difficult to say when so many things have been changed,

Just remind me is it points or Ducati ignition....what method did you use to time the engine,

I presume your using your old carbs....how did the old engine run with them and have you balanced them on this engine

Nick.

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Rotax 503 engine lag

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