My primary oil is always dirty looking when I change it. Gotta be clutch dust mixed with the oil. The trans oil always looks just like it did when I put it in.,,

 

Skratch, I stand corrected. Your manual says same as mine, ie Tranny every 20K and the Primary every 10K with oil changes at every 5K.

 

so as an engineer, is your expertise more valuable than that of the engineers at hd? your post advocates transmission oil changes at less than that of hd who say 20,000 miles. but then you go on to say engine oil changes at 8-10,000 mile intervals.

sorry, i'm sure you are much smarter than me, but i'll stick with the hd engineers and go no more than 20k on tranny, and 5k on engine.

 

i change my oil every 5ooo , the primary and trans gets done at some point during winter storage maintenence period * i also do oil at the same time so i got fresh oil in at teh start of riding season

 

Perhaps the tranny should be 10K, or 5K.
as one who has all new tranny innards due to lack of quality tempering, I will change every 10K for this reason alone. Heck if the oil looks good put it back in for another 10K if you want.

 

In my BMW's, cars, I change tranny MTL every 30k. Dealer says lifetime fill, bunch of BS. Bike, I just change tranny fluid at around 20k. I didn't write down the exact milage it could have been more. Bike just turn 50k mile so I thought it would be good to change all 3 fluids.

 

I change mine once per year, regardless of the mileage. The tranny change for me is part of the old "I was introduced to Harley by a Sportster" thing. With them you change everything because it is the same fluid. Engine and Trans communicate.