what are the problems which may cause a weak spark ? just incase i have missed one , spark is yellow not nice and blue as i would expect , or am i being to fussy 

What have you checked so far?

Weak spark can be caused by:

-old spark plugs

-resistor plugs with resistor wires

-leaky plug wires

-dirty connections on the coils

-cracked coil bodies

-running NGK D7EA plugs without the terminal nut

-low battery voltage

-dirty battery ground

You can get the top nuts at any shop that services small engines.  They usually have a bucket of old plugs that you can take the nuts off.  Those nuts never wear out so you can swap them from the old plug to the new one.

I don't know why NGK doesn't include those nuts with the spark plugs.  I was able to get a bag of a dozen nuts by emailing NGK Technical service and explaining that the plugs I bought didn't have nuts and the BMW wires didn't work without them.  I told the tech that I had been using NGK for nearly 50 years and didn't really want to change brands just because they didn't have those nuts.

will not have this happen again just bought 50 off ebay . im hopeing this may cure the poor starting, will not have helpped , can not belive i missed this i must be getting old , im sure i will be back with the next problem but for now thank you . 

ITS only Blinding Bloody Obvious, after we have found it, makes us laugh or cry depending on have we spent any money or not, we have all done it at some point.