Hi everyone,
I have a 2 cycle engine from a weed whacker that just wont start. it's in good condition, i took it all apart and cleaned/oiled everything properly, but when i crank it, it doesnt fire even once. i do the trick where you take the spark plug out and touch it to the side of the cylinder, and i CAN see a spark. it's blue but very small. looks like a hair's width and jumps across the gap. when i spray starter fluid right into the chamber or in the air, the spark CANNOT ignite it. could there be a problem with the ignition coil or something?
thanks

Sounds like you have the kill wire grounded. Check your wiring, I assume its a magneto being a weeder, There is usually a wire coming out of the coil, If it' grounded there is no spark.

Most weed whacker engines need to be spun quit fast to generate a good spark, maybe faster than you can flip it by hand.

Try an electric starter. If you see any sort of spark when flipping, it'll start.

But, you have to realize that without the plug in the cylinder, the engine will spin faster when hand flipped as it will when the plug is in the cylinder and there is a lot of compression.

Also, raw starting fluid on a sparking plug is quite dangerous. Not a safe thing to do if you value your eyebrows.

If you can see a spark, then you have enough to get ignition.
You may not be spinning it fast enough to start.
Is there a pull cord or something you can use?
If not, you may have to use an electric starter.

i am using a socket driver bit in a 9.6 volt cordless drill/driver around the nut on the crankshaft to crank the engine, not my hand.
also, the kill wire is not touching any grounded surface.

if i am spinning it fast enough to see a spark, could i be spinning it too slow for other things to happen that are to key to ignition? in other words, what else is caused by cranking the engine besides creating a spark and moving the piston?

the spark plug is brand new. i always thought the spark should basically encompass the center electrode on the plug when it goes off, not be a tiny little flick!

thanks for the suggestions

probably not fast enough, magneto ignitions need from 300 to 500 rpm, most cordless drills aim for 500 rpm, no load. a 9.6 probably isn't getting up fast enough to start it. (I've tried with my 14.4 drill, and that just barely starts it, if the engine is in a good mood)

wow, i guess i underestimated what it takes to start this thing!
ill have to pursue a new method, thanks for all the suggestions

Your don't say how and if it's getting gas. How are you choking it to richen the mixture? If it doen't have choke plate, a cork on a dowel works like a charm. Did you rebuild the carb? Maybe its just plugged up with gunk with old diaphrams etc. If it sparking and getting gas it should fire even if it won't run.

i opened up every part of the carb and blasted all the holes with carb and choke cleaner. when i crank it, im opening the throttle all the way and plugging the choke. i have the high and low adjustment screws seated and then backed out 2 full turns.

would the engine fire once if i sprayed the carb and choke cleaner right into the cylinder and then sparked that by cranking?

THis is NOT the proper way to start this engine.
Close the thorttle to idle, choke the engine until it is wet, then try and start it.
You may want to contact some of the knowledgable people on this system to figure out the high and low needles settings for an initial start.