my blaster is making a clicking sound on top of the engine, but i took everything off and the piston is fine. she starts right up and drive hard and has great compression. sounds like the piston is hitting the part where the spark plug is.
oil injection gave out perhaps? what does the plug look like? if it were hitting the plug, it wouldn't run for long as it would close the gap within 2 or 3 strikes...
first of all, shado it cant touch the spark plug. have u ever seen the head taken off? also he didnt say spark plug, he ment top of the combustion chamber.
and that would be pretty bad. did u check for play in the crank bearing? up and down play is bad. but if it even had up and down play, it probably wouldnt run.
you just have to take the head and jug off. you said you already had it apart checking the piston right? you just take it off so u can hold onto the connecting rod and try to move it up and down. DO NOT bend it side to side it will wreckthe bearing. do you know engines? like could you even take it apart? before you do, give us a video with good sound quality so we can listen, and move the camera around different parts to see if it gets louder or not.