my honda 300ex backfires when cranking, it'll run then bog and backfire and die. it will only crank when choked, wont run well at high rpm's, it was smoking kinda white and blue and when i cranked it i ran it to the rev limiter the let out and it would bog and die.

 

Sounds lean. Check for a leak in your air intake....sounds like it is getting to much air. Take the air filter off, and hold your hand over the opening while you crank the starter a little. It will not hold a vacuum if you have a leak.

 

it will suck the intake hose flat, however it won't crank anymore.

 

even with the airfilter on, lid on it wont crank

 

It won't crank over or it won't start?

 

it wont start

 

spark plug .......ive had smoky machines and every time this happend to me a new plug always helped, and it sound like the carb needs cleaning

 

Sounds like the timing is off or you sheered the key on the mag.

 

you think y2dat might be right, i lost my sparkplug tool so icant tell

 

Could be a lot of things. Difficult to tell by an internet description.

Did this come on suddenly, or has the machine been doing this after a period of storage?