Ok, I made another change. I can fit a 47 pinion with a HB 110 spur. With the motor at its maximum adjustment and the pinion adjusted away from the motor so it does not make contact with the motor mount... a 110/47 combo is a 4.56 final ratio.
With the pinion out a bit, alignment with the spur is not possible. Not with my fat pinions. So I made a 2mm spacer for the spur and I then had alignment with proper mesh.
Don't flame me, but the screw behind the spur is blocked. I had to tighten the visible screw once proper mesh was made then lift the spur tightening the last screw. Sorry! The extra steps of removing the upper deck and lifting the spur is good for ya! All this for the desired final ratio with a spec 17.5 class. With this spacer and the smaller 96 spur... I won't bother guessing the possible pinion size.
Take note, I was able to use the same screws for the spur. But, if a thicker spacer is used, longer screws may be needed and avoid contact with the front belt pulley, it would not be good. I had plenty of space between the screws and front belt pulley.
Now at one time, I recall seeing really thin pinions... they would make all that I did moot.
Pics to look at=>
Attachment 642930
Attachment 642931
Here I tried a larger 55 pinion with the 96 spur. The motor is slid forward. I wanted to see if the pinion would make contact with the lower part of the motor mount... it did not. Notice the gap in the spur and pinion. Final ratio is 3.4. Where would anyone need more???
Attachment 642958