Sym jet4 no spark after head removal but sparked before help

[matty67832011]

Hi, i have a sym jet 4 - 4 stroke, i recently took the head off to have the spark plug threads re done, now since i put the head back on there is no spark... There was a spark before this, and i have been told that even if i put the cam chain sprocket on in the wrong place it would still spark it just wouldnt run...
So im very lost, i have checked all wiring, i have cleaned the pickup, i have removed earths cleaned and put them back on, i have changed ht lead and cap. I have fully charged the battery...
One thing i did notice, after re charging battery the other day when i went to put it back on it blew the fuse thats near the battery so clearly something was shorting out so i checked and the two big wires that run into the thing that sends the power to the starter motor those two wires were gouged and close together so i can only assume they were shorting and now i have taped them up its ok when i put the battery on.
If it was shorting Could that of damaged my coil? Cdi?
its just so strange it sparked fine i took head off i marked it all up so it went back on in the right place and now no spark... I found a manual earlier for this bike, and its pretty useless although it did say one thing that maybe someone could make some sense of... -

''The ignition system equipped with a auto-advanced timing device in CDI unit. Thus, ignition timing
need not to be adjusted. In case of incorrect ignition timing occurred, check the CDI unit or alternator
system. It has to check the ignition timing with the ignition timing light if replaced these components.''

WHat does that mean?

Any help no matter how little would be highly appreciated
Thank you

[Aff]

There was another CDI issue on here recently, here is what I posted, your gonna need to get your multimeter out and start taking some readings.

[bikenut]

:D could you put up some pics of what youve done..............

[matty67832011]

Thanks you 2 guys, i have just got the bike running, it turns out there was a cut out switch that 'someone' had put on under the seat, but because i had all the panels and seat off i didn't realize that till i saw a plug hanging lol so it starts BUT i could still do with your help setting the timing perfect, it seemed a little lumpy (could be because of old moldy fuel so will put fresh in it) but i want to be sure the timing is spot on,

Now there is 2 marks on the flywheel, one is a line with a 'T' on it and one is a line with a 'F' on it. when i line the F up with mark on crank case the lump on flywheel that passes the pickup thingy the lump is Just nearly past that generator bit, but if i line up the T with the mark on crank case it make the lump on flywheel a bit further past the pickup generator thing. So which do i go from?

i believe the 'F' stands for 'FIRE' and the T stands for 'TOP' id only assume that it has to be the F that's lined up with crank case mark as that makes sense because that makes the lump on flywheel in the position where the pickup bit is.

But please correct me if im wrong.

So i line up one of these then take cam chain off again and move cam sprocket round to its mark with crank case then thats it right?
Or should i just LEAVE it all as it is, it started pretty quickly and isnt KNOCKING so shall i just leave it?

when that notch on flywheel passes through under the pickup generator does it create the spark as the notch is under it or as it leaves it or as its completely clear of it?
So hard to explain all this without giving you a photo i did try and take one but it was blurry as it was so close...

Thanks for your help.