I'm in the middle of changing fluids on the wife's 18 Fatboy and according to the service manual it gets different amounts of fluids depending on if it has a narrow or wide primary. My problem is that I'm not 100% sure which it has, narrow or wide. Can I get some input from everyone ?...

Thanks...Scott

 

2018 - Wide Primary Cover (25700685)
2019 - Narrow Profile Primary Cover (25701040)

 

You should fill it to the level shown in the picture in the manual. The volume information is only approximate. I think it says that right there in the directions.

 

2018 Fatboy has the wide primary... I'm still looking for info on how to swap to the narrow.

All 2019+ Softails have the narrow

 

You should be able swap it easily. Narrow primary cover requires gasket and narrow derby cover in addition for 2018 models.