"A manual or three, correct tools, proper parts, and a lot of patience are all anyone needs to pull off the deed."

Add plenty of pictures taken as the beast comes apart, and plenty of help from the guys here.

Helped my brother in law completely disassemble his 74 DT125 Motor this weekend. We initially thought his crank bearings were ok and were gonna leave them in. We decided to do the job right and split the cases. Well, long story short, although everything we could see before splitting the cases looked and felt fine, once we got inside it was a different story. Moisture had gotten into the crank cavity and the lower crank and crank bearings had surface rust. Once we got the bearings out and spun them by hand, we were very happy we decided to replace all bearings. Gonna ship the crank off toBill Bune and have it redone. My point is if you have to ask if you should do it, then it probably means it needs to be done.

I think you have a air leak somewhere. Has the crankshaft seals been checked and or replaced if needed? might make or find a way to pressurize the crank case, this is also called a leak down test. the crank case on a two stroke is alternately under a vacuum and under pressure and there should be no air loss there. if the engine gets air in any other place other than the throttle slide and there is enough fuel, you will get a run away. at least a 2 stroke run away is no where as catastrophic as a diesel run away. the worse you will likely get is most likely a seizure.

Thanks to all of you this has been a very informative session for me. I did find the crank seal shot all to hell once I pulled off the armature, and like one of you had pointed out it was on the electrical side as that seal is dry. I found it very interesting, not having any 2 stroke experience before this, that the one side is a dry seal and the other is wet obviously because of the gears and clutch. I ordered all the seals together but replacing the dry side was all it took. I also found the seal holder had broken near the top mounting screw. So I ordered it when I ordered the seals.
Unfortunately when I got it running, and it ran great, the retaining bolt for the governor came loose and when it got caught up it sheared the sear pin on the crank, so, tomorrow I try to find a replacement at Elliott's hardware and I think it'll run again.
Question is why did it come loose? Either I simply didn't tighten it enough or is there a vibration from the crank bearings causing it to work itself out? We'll see when I reassemble it hopefully tomorrow.

I would still be interested in buying the governor if you are willing to sell the one you have. My cell number is 469-744-8831 if you'd like to call me to discuss price and shipping arrangements, please do ASAP for you to make it easy for you. In fact, I would be interested in buying the whole engine if you wish to sell that. For my next project I want to build a shifter go-cart and will need an engine for that

Thanks everyone for all the help, not only did it save time but it is very cool to see what everyone else is doing. I'll check back tomorrow to see if you've posted anything else about selling the governor. Thank you!

Very cool, I always love watching 1320 videos they seem like a bunch of fun guys...

FIXED-TRhe crank seal was the ticket. Thanks to all for the help! Off to the park for a ride....