How do I tighten the chain on an 1986 Trail Boss 250? It looks like there's 2 lower bolts near the center of the rear axle that pivot forward and back, and it appears that it may already be pushed back as far as those bolts will allow. Wasn't sure if there was any other adjustment to be possible to make, or if I need to take the chain off ... and take out a link? then replace?

I assume I need to tighten the chain because over even some smaller bumps at any sort of speed, it seems the chain will come off completely. And when I use the rear brake, or clutch brake that locks up the chain, it sort of bends down bad when the rear wheels try to roll forward with that brake engaged.

 

If it is like the newer TB's, the axle has two eccentric lobes on the housing. These can be unclamped and rotated to supply more or less tension. Picture a cam shaft with the lobes that operate the valves. The axle housing is nearly the same and as it's rotated, it places the center line of the axle closer or farther from the engine, therefore loosening or tightening the chain. Hope this helps.