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No the wire is fine it has spark.Just apparently not enough to start.
roebuck the keyway is fine.This engine hasn't had a lot of use and the flywheel is on correctly and no signs of wear.

Blumbly, Is it possible that the ignition coil could be bad? I know you have bright blue spark, but you said that it was running poorly. Maybe it was slowly breaking down and now will not work under load. Just a suggestion, swap a coil from another known good quantum, and go from there. Then you can verify that the ignition coil is not at fault. If this doesn't work try disconnecting the kill wire and give it a final starting.

This may be the problem, we do have an ignition tester at work, to test these, but as you don't, swapping a known good one will do just fine and setting the proper air gap.

Well I'm at a lose now have pulled it apart again.Just can't work out what is wrong with it.Has a good spark (so I can't see anything wrong with the coil pack).The key-way is all good (a nice tight fit).Spark plug seems to be working fine (gave it a good clean).The gap for the flywheel is fine.Fuel not a problem either,everything points to a running mower,but not.The only thing that does seem to be not quite right is I gave it a spray of start you bastard and it tried to fire,only problem was it's timing was out.Now if it was a car I'd say I had the distributor out by 180 degrees,but it's not.However I'm thinking it has something to do with timing.Now that is a problem as I'm not to crash hot with four strokes.I'm a two stroke guy,give me a two stroke and I'll get it running.The only thing I can think of is the cam would be out slightly,but how it was running I only pulled it apart to fix an oil leak.I've even gone back to the basics which is how an internal combustion engine works which is. Suck,Squeeze,Bang,Blow,now from that I'm thinking that the bang part is not right.Please help if you can I'm really stuck on this.

seems funny as it was running before. your timing shouldnt have changed too much.only thing i can think of is maybe it has a stuck open valve. if its firing incorrectly it would probably misbehave like back fire or something?
the first stroke the fuel valve opens to let in fuel. you said its getting fuel so that cant be stuck closed.the exhaust valve needs to stay closed till it fires then open on the exhaust stroke to let the the gases out. maybe the valves are broken or stuck open.
or the timing is 90 degrees out and its firing on the exhaust stroke.

I just don't know,it just doesn't make any scene to me at all.

OK weird yes that's right weird.I don't know what was going on,but I have a motto.That is never give up,so keeping that in mind I decided to pull it apart again right down to pulling the plate off and resealing it.Not that it needed it,it was all good.I put it back to together except the fuel tank.I sprayed some start you bastard and pulled the cord,it fired.I thought, WHAT??So I put the tank on gave it some fuel and right there on the first pull away it ran.Like it never had a problem.So I'm happy to say that the mower affectionately know as Brum Brum is now back to running.I don't know what was wrong but it's not now.I'd like to thank everybody for there help.There was quite a few good ideas in there.It's great to know that when these problems come up there is people that are happy to help.
Thanks all.

wow. far out. well the mystery will forever remain a mystery. i am glad its running good for you now .

Lol. Good to see that it is running.

I used a similar solution at work once when the brake pedal on a Bolens ride on wouldn't depress at all. Completely stuck. So after lubricating things, I decided to completely dismantle all the brake linkages. Everything was free at the gearbox. It did not make sense to me why it was sticking. So after seeing that nothing was wrong, I reassembled everything, and it all worked perfectly. I didn't do anything but disassemble and reassemble. lol.

Sometimes when working on mowers. Stuff just happens. Lol

Yes, a lesson for all of us. Sometimes you just have to do things twice.

Yes but still doesn't make sence. There must have been something but I couldn't find it. I guess alls well that ends well. A mystery it will remain.

Well the mystery continus went to start it last night and once again no starting. However this time I have a theroy as to what is causing this. I'll let you all know if I'm right.

OK well I know have do it this time.After just taking a step back from it I had a good think as to what might be the problem.Then like in those Warner Brother cartoons the light bulb was above my head.So I pulled it apart for the third time.I even pulled the plate off and then started making up a new gasket,as the theory was the gasket I put on the first time wasn't doing its job.I don't even know where I got it from.My theory was replace the gasket as maybe there was a vacuum leak through that gasket,as that is what started this hole problem.So I got (Prum Prum) back together.Now I did cheat and added a little spray of start you bastard.On the first pulled it was alive!! I ran it for a few seconds,then stopped it.Primed the carby and started straight away.Them mowed most of my lawns (just lazy so I didn't do it all).Waited a few hours and started it again,all good.So mystery solved it was a vacuum leak through the first gasket I put on it.The second gasket is all good.Once again thanks for your help we got there in the end.

amazing what standing back and a good scratch will do great to hear it doing the job again

I knew you could fix it Blumbly!

Thanks guys I knew I'd work it out. I guess I was just trying to get done to quick as I have a lot of mower jobs on at the moment. Next time ill just take my time. Make sure the new gaskets is good enough to do the job.