Home Forums Autocross / Solo 2 FJB/FJA World Formula Reply To: FJB/FJA World Formula

Scott Boito

Hey Robbie,

We made this switch earlier this year after running the KT100 for 2 1/2 seasons.  After a few months of growing pains we finally got it figured out and it’s a dream to run now.

Initial costs are higher than the KT100, but there are minimal hassles associated (no starter battery to charge, no charger to lug around, no tuning of the carb).  The weight of the motor is our biggest problem to overcome since it’s more than 2x the weight of the KT100.  Corner balancing is still impossible side to side due to Kieran’s size.  I had to move it pretty far forward to get the correct front/rear split, but the chain is super long as a result.  It will get better as he gets taller and heavier, but it is a real limitation.

He’s on an older Top Kart SL28 chassis with a moveable seat stay and using a two piece mount easily allowed us to mount the motor without interference from the seat/seat stay.

My advice: work that clutch early in the process.  The clutch was our only source of consternation those first few months.  It wasn’t until he ran it at a track that it properly broke in and started functioning as it should.  After that it has been a dream motor.

As for gearing ratios, I gear it between 17/73 and 17/65 for JB (#219 chain).  Next season he moves up to JA and I’m getting a 19T clutch sprocket so he can get up to higher speeds with the same axle sprockets.  The 17/65 was perfect for Blytheville Summer Nats this year.  17/67 would have been the perfect choice for Wilmington.

If you’re interested in running #35 chain, PM me as I acquired several fast #35 axle sprockets that we’re not going to use.