Motorcycle Repair: 1989 Sportster 1200 Jerky-ride Problem, garage mechanic, harley dealership

Question
I have a 1989 Sportster 1200cc 4-Speed.

It was in an accident a few years back. The front end and the gas tank were replaced by a Harley dealership after the accident.

When I got the bike back, the engine ran rough and sometimes the clutch would not work. I found a garage mechanic and he got it running really good. There was a bolt loose and one missing with something to do with the clutch I believe. And he made some adjustments to the carb and the throttle linkage. The engine ran great and it has always shifted fine after that.

But even then, there was always a slight "herky-jerky" feel whenever riding at a steady speed. Doesn't matter what gear, anywhere between 2,000 and 3,000 RPM's at a steady speed, the bike almost seems as though it's going in and out of gear sort of. If I pull in the clutch, it coasts smooth as silk.

I took it back to the garage mechanic and he tightened the primary chain and jetted the carb to 175. He also got rid of a couple of oil leaks by replacing the seals/gaskets on the top and bottom of the jugs.

When I got it back, the herky-jerky was worse. So then he loosened the primary chain. Still herky-jerky. Then replaced the secondary chain because the old one had a couple of stiff links. Still herky-jerky.

Finally, because of the herky-jerky, and now that it was jetted to 175 and fouling plugs, I gave up on the garage mechanic, and I took it to a friend of mine. He did the best he could to get it back to the best it was; basically by re-jetting it to 165. He even found the mixture(?) screw out seven (7) turns. He went by the book and turned it all the way in and backed it out 2-1/2 turns. Then he adjusted it just a 1/4 turn from there. I have not fouled another plug since. He suggested that the herkey-jerky problem was timing and he did not want to get into that himself.

So now I'm back to square one (I think). It runs like a raped ape when accelerating. If I was drag racing, I'd have no problem with it. But riding at 35 MPH or 45 MPH is just not comfortable at all! It makes me not even want to ride it. I still do though.

My gut feeling is that it is something to do with the trans or gears somewhere. But everyone I talk to about it seems to always suggest its the carb and/or the timing.

Some additional info to the best of my knowledge:

My father was the second owner, I am the third.

It had very low miles when he bought it in 1999, something like 5,000 if I remember correctly. It has a new tach so I'm not exactly sure. I just remember it was real low miles for a 10-year-old bike.

It also has after-market exhaust.

Any help you could provide would be greatly appreciated.

Thanks,
Roy

Answer
The jerking is probably related to either a clutch problem of a trans problem. If the timing or carb were off it would run rough, but not jerk. I would start with the clutches and check them for wear. If you dont find anything there them check the sprockets to make sure they are tight. After that you will need to pull the trans and do an inspection on it.
Good luck and happy riding
mike