These aren't motorcycles.
Engine braking on these motors doesn't too a whole lot honestly. Yeah it slows you down a little, but I find it's a smoother ride if I just clutch in and use the brakes. With this kit you wouldn't even need to clutch in if you're just slowing a bit for a corner.
Just my $0.02
I was raised on motorcycles... I rode a 4-stroke MB with no engine braking, & I didn't like it at all!
The general opinion of the jack shaft kit, with my friends & customers, is that without engine braking... we don't want it!
If you rode motorcycles, you would get what we're saying!