I know I'm making a total stab in the dark but I gotta start somewhere, before I go to my local bike mechanic and say, "Here, fix it." My bike that I had running two years ago went dead on my last ride which then sparked a total strip, sandblast, and re-finish. I have a video attached as part of the last ride. It was a 9-minute ride; it was running fine and then suddenly it didn't. I did shorten the video to two minutes so you can hear it start up, you can hear it run at a 8X the normal clip, also it running at regular playback speed before it died
I spoke to my local mechanic, he was suspect that it was a carburetor causing that, since I told him also about the issues I was having with the overflow and such which were remedied with the original carburetor. Other circumstances occurred where I needed to buy a new carburetor as it was so I now have a new carburetor on it.  Still now I've got the bike together and I'm still stuck with the same situation where it's a non-running bike.
 With a new carburetor (other than setting the air jet screw at 1.5 turns out), should I go over everything on the internals of the carburetor making sure that the floats are at 1 inch above the float bulb base and all that sort of stuff?


The only other thing that I can think of is... I don't know what else to think of. Maybe crank seals? 


i.imgur.com/an4f8Pb.mp4

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... it suddenly died. Intuition : Spark related

From the video it behaved as if you hit the kill switch. Did you check for spark? Sometimes an electrical component will work fine until it gets to a certain temp. If it has spark, put a bit of starter fluid in the combustion chamber and give it a kick. If it fires and dies you have a carb or fuel flow issue.

Well I'm glad I went back out there and checked. I knew the gearbox was low so I topped up the oil.
I thought I had drained it all out to do the work that I was doing. Evidently I didn't because it topped up really fast. Too much oil on the dipstick, so I went underneath and looked at the drain plug which was leaking because it wasn't tight. It's a good thing that got found out. I drained out enough to get it down on the proper mark so that's all good. 

I went ahead and figured, "What the heck," I'm going to try kicking it again and it popped once. I was really surprised. Then I tried it again and it popped again. After a number of repeated tries, I got it started and running. I was going to let it warm up because there's still the high heat temp paint that has to bake in so to speak. So I'm just sitting here letting it run and gunning the throttle a little bit, not too high of an RPM but just gunning it every once in a while, kind of enjoying the moment I was at the time.

With that once I'd gunned it once, the throttle acted like it got stuck although I can still feel the resistance on the cable. I was freaking out because it was running at practically full RPM. As a note before that even happened, I was noticing the3 bike vibrated a little bit more than usual. At least from what I recall.

So with that I'm struggling what can I do to shut this bike down? So I grab one of my ratchet wrenches and try to hook the spark plug wire off which I did but it shocked the living crap out of me and it did not stop running. So I am now freaking out. Evidently this thing is dieseling or something like that.

So I finally got my act together and put the thing in gear and stalled it out. So guys, what do you think of that? 

Air leak
 

Just wanted some clarification on what you had mentioned, Mark. The bike did get fired up surprisingly. I wasn't expecting it to for all the trouble it gave me already. But when it fired up after a time, as you may read on my last post before this one, that thing revved up on its own. When I pulled the spark plug wire, I mean literally THE spark plug wire, I yanked it out of the socket since I didn't pull it off the spark plug itself. So when I yanked the wire out of the socket the bike is still running!!
 

A great way to learn about keeping up on maintenance on your vintage bike is to watch someone like " 2vintage " on youtube and look for your bike or a similar bike. He usually purchases non running bikes and then 'trouble shoots' them until he gets each problem solved and then gets the bike running again. It makes a fantastic crash course for getting to know the ins and outs of your machine. I get so much value out of these kinds of videos. The only downside is, you can easily kid yourself that you can restore a non running vintage motorcycle in just 1hour and 15 minutes, lol ! Hope you get riding again soon

What you described is the classic two stroke air leak symptom, "runaway".

I bought a 79 DT175 cheap after the owner had spent big $ at the Yamaha dealership and a local shop.  My heart sank a little when I looked through the receipts and saw that both shops had pressure tested the engine and it passed.  

I pressure tested and it held 5psi overnight.  WTH?  So I vacuum tested and it would not hold any vacuum.  Long story short, the ignition side crank seal sealed under pressure but leaked like a sieve under vacuum.  

Honda actually built two stroke in the 1990's that used a computer to control this exclusive two-stroke phenom they called "Activated Radical Combustion".  I had one for a few years.  It actually shut off the spark during certain riding conditions!  A two stroke is very efficient under those conditions.  Fuel economy goes way up and emissions go way down.

Listen to MARKT

Thanks for your input Mark. I value it highly. I've seen your answers for other folks on this forum. I understand you were a Yamaha mechanic for a while. That's some great credentials.

Reed Valve Richards, recommended going to the 2vintage YT page where they're working on vintage bikes. I never knew something like that existed. That'd be pretty cool to see. I'm a great backyard mechanic myself. I've been owning Yamaha's and working on them myself in my younger years so I'm pretty handy as that goes. It's just that the air leak stuff and what it takes to do a pressure test on this bike, I seen it was rather involved.

I think I'm going to take a to Tim at Cycle Therapy in Bellingham and say, "Here, fix it."