how do you know if you have strong spark on a honda atc 125m

 

As a rule of thumb on modern engines, if you have any spark you have a good spark. I can't think of any thing that will break that rule. I sure there is some weird thing but it is far from common.
To check for any spark just pull the plug and ground it and kick or turn the engine over.

 

yeah it has awsome spark it is white and it bloes up the gas but still wont start carb is clean and healthy but still wont start whyyyyyyyyy

 

Josh you need three things for an engine to run. Fuel, spark and compression. If anyone of those are missing it will not run.
I would give it some starting fluid and see if it will run. If it starts for a bit and then dies you have a fuel problem. The next thing I would do is give it a compression check and see what you come up with.
If you have good spark it's going to be one of these two.

 

could be a timing issue???

 

Timing won't change unless something broke.
When was the last time you checked the valve lash?

 

its never been checked the dude i got it off of said it smoked like no other and one day he was riding and it just died and its been sitting ever sense and i sprayed starting flued on the plug no fire in the carb no fire im doing every thing and it still wont fire all it will do every now in then is <span class="FTHighlightFont">back fire</span ft>

 

DO A LEAK DOWN TEST. THAT WILL TELL YOU IF YOU HAVE COMPRESSION AND/OR DAMAGE.

SPRAY EITHER IN THE SPARK PLUG HOLE. THAT WILL TELL YOU IF YOU HAVE A GAS PROBLEM.

 

ive done everything and it still wont start just back fire i also got a new spark plug and still no spark what is a valve lash

 

The next thing to do is a compression test. See what numbers you come up with.