I picked up 76'cc 125 a few months ago. Mostly complete. Ordered some parts and a manual from Al. Workered on it over the weekend. I was able to get it started but it has issues. I cant tune the carb to even get close. I will contine to work on it. The penton excites me and I'm glad I have found this forum.
JH
If it is a Bing it almost certainly needs cleaning, new needle jet, new needle, and new needle seat valve. May need new slide too. You can tell on the slide when it is out. If it has worn into it what looks like a smile it needs replacing. Almost all tuning troubles on old Bings are the above parts being worn especially the needle jet and slide.
Larry P
Welcome to the group Jay! You will find an abundance of information here on this site about your bike. Best of luck with it!
1976 250 MC5 Original Owner
1976 Penton 175 XC
Make sure the crankcase drain screw is still in there!