Problem with lexmoto gladiator turning over

Hi all I was wondering if anyone her could help me

I recently purchased a second hand lexmoto gladiator (Chinese gy6 125cc).

At the time I bought it was running but now just doesn't seem to want to start up.

I have replaced the oil (at the time is was running) battery, starter motor, spark plug, checked the valve clearances and put in fresh fuel but am having no luck.

If I line up the fly wheel correctly and put the spark plug on the outside of the crank case the crankshaft will spin freely but the engine will not kick in if that makes sense. As soon as I remove my thumb from the starter button it dies so it cannot idel by it's self. There is also pressure from the exhaust when this is in progress.

It's making me think that fuel is not getting though but there doesn't seem to be any bloackages.

Does any one have any suggestions that I could try?

 

Test your compression