Boom Fun 500 and V1 gearbox.
Some tips with operating.
Do not move gear selector from forward to reverse without engine running.
Don't let people sit on it and keep moving the gear selector, it will bend internally and then damage gearing.
When selecting forward or reverse use only small throttle revs.
Some tips on installing;
Always ensure input shaft is horizontal and not slanted.
Don't forget to put oil in it. 1lt of gearbox mineral oil.