Is it the clutch? What the hell am I missing?? 

I rebuilt the engine on my 1980 Sachs 505 1D Prima G3 because of a scored piston/no compression. The crank was tired and the oil seals were leaking like a sieve so I did the top and bottom for peace of mind. I went slow and followed the shop manuals. It sounded awesome when I fired it up for the first time on the kickstand but it won’t drive under load. The sprocket/chain/rear wheel respond to throttle on the stand. Then I sit to drive and there’s no power to the wheel. Pulling the throttle just revs the engine. I’m assuming this means I have a clutch engagement problem but I’m striking out on troubleshooting.  

I thought (??) I followed the steps in the manual. Version and relevant pages attached. It says to turn the adjusting screw until it hits the thrust cup/pressure pin (check), then back off a 1/4 turn (check), then tighten the lock nut (check). Then make sure there’s enough play with the starter/clutch cable. I’ve also watched this TravisTutorial 10+ times: https://youtu.be/e5psYgHFbDw

I went back in and tightened the screw further in on the thrust cup/pressure pin after the first go. No difference. Not even herky jerk, almost-got-it situation…just nothing. 

I thought maybe I had the wrong gearbox oil. It was running Type F ATF when I got it. That seemed to work fine but I figured since I opened and cleaned the crankcase it would be a good chance to switch to actual gear oil 80W-90. I guessed that maybe I missed some compatibility spec and this was the problem. Drained it, filled with ATF, ran it a few mind, drained and refilled. Still no power, only now I noticed a metallic trilling when I rev. 

What the f### am I doing wrong? Do I need to tighten the screw on the thrust cup more? Did I mess up friction with the wrong oil?? I started this in April thinking I’d have a fun project before summer and now I’m just trying to break in the new piston rings or at least get one ride in before the cold hits. 

If relevant: new piston, rings, re-honed cylinder, Treats performance crank, seals, bearings, and probably more that I’m forgetting. Also…shout out to Shaun at Myrons for being the parts and diagrams GOAT. This is my first moped and first rebuild. Thought it would be easier than my Tacoma top end…I’ve been humbled. 

1980 Sachs 505 1D rebuild headache - WTF!!