Just bought off ebay, did eventually start, long enough for me to do a first
rough cut to try them out.Then they made a `kind of` knocking noise` which I
am positive was coming from the starter string mechanism.
I took this part off and then re assembled noise now stopped but they won`t
start.

I have checked with manufacturer and the idle/fast screws are correct.
I am getting a spark at the plug.
The fuel is getting to the plug.
I emptied and made fresh 2 stroke at correct ratio.
I replaced spark plug with a fresh one.
When turning engine over there is compression and it runs smooth with the
plug out (or in) so don`t think any engine damage.

I have motorbike engine experience so don`t think any major engine probs.

Help what next?????

It says press `bulb` 5 times for fuel? could I be flooding the carb? I ask
in case it is my starting methods although I am going by the manual.