So, two problems:

First, I just purchased this 2005 Loncin 250cc for $300, got it running, and reverse worked fine. I had a little trouble shifting it into reverse a few times, but it eventually slipped into reverse. After a few test drives, the shifter just stops at neutral, halfway between forward and reverse, and won’t shift into reverse. I tried messing with the linkage, but it didn’t solve the problem.

Also, when I drove it around for a little while, I noticed a gear-slipping sensation when driving in gear at lower (maybe quarter) throttle, gears 1-3. When I would punch the throttle, I noticed the slipping sensation much less, if at all. I don’t know if it’s a carburetor thing or a transmission/chain thing, or something else completely. The engine runs really strong and idles great. It hasn’t bogged out once since I got it started, although I haven’t cleaned the carb yet.

Thoughts, anyone? Merryman?

Thank you in advance.

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Update: shifter goes into reverse if I roll the atv backwards a few inches while shifting (weird).

Now, to tackle the other issue of the slipping/jumping/lunging feeling I was trying to describe earlier. No problem shifting into gears or catching once shifted, but after gear engages and holding throttle low and steady.

 

Could be your centrifugal clutch slipping. They usually work fine until the shoes wear down to the metal, then they slip. Yours could be just worn out, or the mechanism a bit sticky. As for reverse, it should work OK with engine running, gear dogs need to be moving to go into mesh.

 

While riding today, the gears disengaged completely and would not go back into any gear, including reverse. I adjusted the linkage and not only did it go back into gear but it fixed the jerking/slipping while cruising at constant speed. I only drove it for a few minutes until it ran out of gas, but it drove smooth and steady at constant low-speeds all through the gears. It even picks up a little bit quicker.

I’ll gas up and go on a longer ride tomorrow to see if this actually solves the problem.

 

I adjusted the linkage from this:


To this: