I have a 2015 1200C, pure stock. I changed the primary case oil using the HD recommended fluid. Shifts great when cold, but once it totally warms up it gets pretty "clunky". It's like the oil isn't holding it's viscosity very well. It did this before I changed the fluid also. What's everybody using in the tranny of their Sportys?

 

Bel Ray primary fluid. It clunks, but not as bad as before I changed it.

 

Did you also adjust the clutch when you changed the fluid?

I am running Red Line 75w-90.

 

HD`s F+ is Sae 50. I run Valvoline vr1 sae 50 racing oil. I adjust my clutches then.
Valvoline vr1 20w50 racing oil in the crankcase.
Sure hope any gear oil is gl1 only.

 

Yup. Sounds pretty normal to me.

Nothing is going to totally eradicate the trademark clunk. How bad the "clunk" is depends on who's listening to it.

If your tranny is in good shape (and I'm assuming it is on a 2-3 year old bike) and you have proper fluid in there, and your clutch is good, and properly adjusted, then it's probably the normal "clunk" you're hearing.

 

Seems like every bike that I have owned has 'clunked' and all owners complain of it including myself. However, I have to admit that the 'clunk' on my Sportster can be pretty awesome at times, even wearing foam earplugs it is both remarkable and apparently remarkably normal. Sigh.