Sprayed ether into the carb and still won't start.  Not seized, turns over, just won't start.  Possible electrical somewhere?  What do I need to look at?  I'm stumped as the bike is pretty simple, is getting spark and gas, turns over, but will not even start to run.  I don't have a manual, so I don't even know what else to do.  Anyone know where i can download a repair manual, owners manual, etc.?  The bike has ran great since I've had it.  Thanks for any suggestions ahead of time.

Try a valve adjustment, the tappets may be tight and the valves aren't closing all the way. Intake setting is .002" and exhaust is .003".
If you've never done it before, remove the left side (ignition) engine cover, and also the big round cover on the head, that is the cam sprocket cover. The bolt that holds that in place is located over the spark plug. Rotate the flywheel counterclockwise until the "T" mark is aligned with the mark on the engine case (12 o'clock position) and the "O" mark on the cam sprocket is lined up with the mark inside the edge of the head (approx. 9 o'clock position). Then adjust your valves.

was it running when last put away?

It was running.  In fact, here is detailed story.  The bike has ran like a lawn mower since I bought it from a good friend two years ago after it ran flawlessly since new for his two boys.  We were in Moab and he had been riding the crap out of it, having a blast.  He came to me and said it wouldn't start anymore.  I went out and after difficulty got it started, but had to shut it down quickly because the throttle was stuck wide open (not the first time the crappy stock throttle has had problems).  I started messing around with the throttle and noticed it was getting more and more difficult to start.  Finally, I got the throttle fixed and now it stopped starting at all.  After the wind/sandstorm slowed down, I took the carb apart and cleaned it.  Still no go.  I gave up with a day left in the trip.  Now that I have gotten home, I gave it a more thorough carb cleaning, put a new gas line on it while I was at it, lubbed the throttle cable and confirmed that it seemed to be working just fine - should be starting and running.

Is it possible even though the plug still gives spark that it has crapped out?  I read a comment about making sure the ground was good on the kill switch, which has led me to want to look into the whole wiring system this weekend.  Reason being is the kill switch stopped working a couple months ago and we've just been using the key to shut it off.  Maybe something finally shorted out there?  No idea, but getting frustrated.  I'm a decent hack mechanic, having owned bikes all my life, rebuilt my truck motor, but man this thing is making me feel like an idiot.  I'm sure it will be something simple which will confirm it when it is all said and done.

I checked the valves and they look good.

The kill switch certainly deserves a closer look, especially since it already was giving you problems.   Try starting the bike with the kill switch disconnected.  Or, put an ohmeter on the two wires.  The switch should be open when ON and closed (continuity) when OFF.

You might as well replace the plug.  It's a cheap and easy way to eliminate one variable.  I had a plug that gave spark when removed from the cylinder and tested, but wouldn't fire when installed.  Chased my tail for hours messing around with the carb and everything else I could think of.  Replaced the plug, and it ran like a champ.  For whatever reason, the Japanese spark plugs (NGK) seem to fail too frequently.

 Punkinhead, on 15 June 2012 - 09:10 PM, said:

My first thoughts would be electrical....Coil check. I would replace the HT lead and spark plug to be sure. Do an Ohms test on the spark plug cap and Ohms test on the coil checking primary an secondary circuits. Coil can give spark with the plug out of the pot but installed it can be a different story. Is the plug wet when you take it out after starting it 10 or so times. If so replace plug first. If the coil is faulty then this could have affected the plug. I have a coil sitting on the bench at the moment for a PW 80 and it gives spark but runs poorly. When I do an ohms test the results on the secondary are nil. If I move the Ht lead while doing the Ohms test I get an intermittent result. This eludes me to a coil issue. I have a new one coming. $ 20.00 from the States. Certainly check the kill switch and earthing Ohms first as mentioned by PH above. This would be the best place to start.

Thanks for the suggestions fellas.  Anyone know where I can get a schematic of the electrical on the bike and/or better yet an on line copy of a manual?  I'll give your suggestions a try.  Was going to get him a new bike at the end of the summer and and am hoping I don't have to do this now.  Regardless, this bike is going to his little sister so I have to get it running at some point.

Here you go, the CRF50 should be the same...

So any news on this animal? I am curious on what the solution was......