Yamaha 25HP - 2 stroke - tickover problem

[Vipermax80]

My 2004 Yamaha starts first pull and runs nicely with a bit of revs, but doesn't want to tickover, if the twist throttle drops anywhere below what appears to be the choke position on the throttle (pic attached).

The engine needs a service, but any ideas as to what might be the issue?

Thanks. David

[A1an]

I'd start with a carb clean. Did this symptom appear after storage of the engine?

[Vipermax80]

Yes been in storage for a good while.

[A1an]

My guess is it's been left will fuel in the carb, this evaporates and can sometimes gum up the tiny holes in carb jets.

[Fenlander]

My action to try and resolve would depend on how it's behaving. Badly blocked idle jets will often mean a motor will only start with the throttle quite a way open and the moment you wind back to anything like the idle position they will stall almost as if switched off.

Is it doing that or starting OK just over idle and then misfiring a bit for quite a few a few seconds before finally stopping?

If the latter I'd try raising the idle speed screw/s a bit to see if it will keep running at idle with a modest adjustment. It is just possible if it were put away at the very lower limit of its idle speed range it needs that bit of increase until it's run for a while is all it needs.

Is it running on the fuel left in storage?

[Vipermax80]

Fresh fuel being used. But the engine has not be running for long, only on a stand and muffs.

Another pic of the hand throttle attached, will continue to run nicely when the two arrows are aligned i.e. will seem to run indefinitely and not die, when revving the engine harder, you do get the odd cough, but again the engine keeps going, doesn't die. Its only when you twist the throttle further back into what I am assuming is the tick over position, then the engine virtually cuts out straight away (bit like pulling the kill core).