First time poster here - although I have come here for help many times and been able to find what I needed from someone else's issue.
I have a strange issue with a 1980 Clinton with the Sachs 505 engine. Last fall I replaced the clutch cable and decompression valve. After I did this it seemed to run fine, but I didn't really ride it much to know. This summer I finally got around to getting it back up and ready to sell. I got it all cleaned up and took it out for a test drive, but about a minute into the ride it started to sputter and eventually died, causing me to have to pedal it back home. I have tried several things:
1. Disasembled the carb and cleaned everything out.
2. Cleaned the points on the magneto.
3. Checked for spark. Seems to be good from my limited experience.
4. Checked the piston for any signs of wear - in case I wasn't getting good compression. Ended up breaking one of the piston rings, so just replaced the whole piston and 2 new rings.
5.Took the in-line fuel filter completely out of the picture.
6. Removed the decompression valve and replaced with 10mm bolt.
It usually starts up on the first or second kick, but I have noticed that it now seems to be sputtering out in a matter of a few seconds rather than a minute or two.
The strange thing is, when I give it some throttle it bogs down and dies, but if I give it throttle and pull the clutch lever it sounds great.
Totally lost, and no idea what to try next. Any help would be much appreciated.