Drive belt slipping off on reversing

[SubjectX]

Hey guys.

I have a problem with my drive belt.

When I drive in reverse, it starts to slip off, yesterday i had him half off the sprocket. When I go forward, it centers itself back to the correct position..

What to do?

[PW2013STL]

Check your belt tension as it maybe loose. Easy way to do that is at the midway point in the belt twist the belt by hand, and if you can twist it past 45° it is loose and will need to be adjusted.

[SubjectX]

I used Krikit to tension it and I also have that extra belt tensioner below..

Anything else I should check?

[Warlock]

I used Krikit to tension it and I also have that extra belt tensioner below..

Anything else I should check?

How close to the inside edge is the belt running while going forward. It should be about the distance of the thickness of a hacksaw blade. Your alignment might need checking again. Also how many miles on the rear end bearings?
David

[SubjectX]

Its about 2mm from the inside edge. I did around 10k km with this bike..

[Snowbelt Spyder]

I used Krikit to tension it and I also have that extra belt tensioner below..

Anything else I should check?

Could this have happened about the same time you installed the extra belt tensioner? If they aren't pretty exactly parallel to the belt, they can "steer" the belt one way or the other. Quick check would be to tie back the tensioner off the belt and see if there is any change in your problem. Check both forward and reverse without the tensioner and see if your alignment changes. You might also want to check that the bolt on your front sprocket is fully torqued to spec. Otherwise, an inspection on your rear wheel mechanics such as axle, bearing, etc. If it's not the tensioner, then something is shifting / moving a little when in reverse. It is normal for the belt alignment to change some between forward and reverse, but usually not as much as you have.