Jerry, please read Bruce's comments carefully - he has repaired more mowers even than Joe Carroll, and he knows whereof he speaks. Also, remember that while your ignition coil does not seem to be the problem right now (if choking it consistently improves its running), it is a known weak link in your engine's reliability.
Because you don't have a fuel filter in the tank, you are at risk of having a blockage in the carburetor fuel intake upstream of the needle-and-seat: the funnel strainer is way too coarse to do the job the fuel filter does.
The inlet pipe is the tube from the carburetor to the engine's intake port: if it were on a multi-cylinder engine it would be called the inlet manifold, but on a single cylinder engine it is the intake pipe. It is under vacuum when the engine is running, and any hoses that run off from it can be a source of vacuum leaks if they are missing, split, or disconnected at the other end.
Having said all that, the single most likely cause of your problem is dirt in the main jet, which is the external, screwed-in device that holds the vertical plastic disk that is the side of your float bowl. A plastic carburetor guy (not me of course) would be suggesting, given that you don't have a fuel filter, that you begin by removing that and blowing it clean. See "jet assembly standard" in this diagram:
<snipped>
Thanks Grumpy,
I've noted your comments and will take action.
The main jet is one of the things that I always check first and is clear. I hear what you are saying about the fuel filter but am convinced that is not the problem right now as I've had the tank off so many times lately and cleaned it each time and checked fuel flow as well as the filler cap breather hole. I have also removed the main jet each time and cleaned it with thinners and compressed air. I'm convinced that the fuel is reaching the carby without any problems and, if the problem is fuel related then whatever is happening must be from that point onwards. Either the inlet needle sticks, main jet blocked, or further along the line.
I've checked the needle (it's free, not sticking, and inserted correctly - sharp point first) and main jet often.
Thanks for explaining "inlet pipe" - what I always incorrectly call the manifold :-)
That made me think, (and maybe this is one for the plastic carby "masochists" as you call them). The rubber plug for the cutout wire on this carby could be suspect - it is worn and does not seem to be a good fit - could air enter the inside of the carby through that and, if so, could I safely remove it and plug the hole? - the one cutout wire to it is already disconnected (and taped up) and I could easily fit a separate external cutout switch. As it is, I stop the motor by closing the fuel off.
Thanks again for taking the time to help.
keep well,
Jerry
