B4 geearing (84t spur 7.5t)

[RDG 40]

Can anyone guide me to a gearing for a B4 searched all day and cant find answer

I bought it and it seems to have an 84t spur, im racing sun so no time to change it.

Running a LRP X11 7.5t brushless.

It my 1st meeting back for 10 years properly so its all new this brushless lark.

Also for future refernce whats best spur to have on for this motor, most set up sheets i find are 70 ish spurs but no definate one stands out.

Thanks

Russ