Talking to a guy I have ridden with a few times. He was talking about a leak he has encountered in his primary. He said he changed over from the Harley Primary Fluid to a heavier fluid. I didn't think to ask him what weight. He may have even told me and I didn't hear it at the time. But, either way, I like to run it by the motorcycle minds on here to get a few different takes on it. He went on to say that the reason he is running a heavier fluid is to cut down on the primary noise, shifting noise, etc. What do you guys think?

 

He was probably referring to 75w-90 gear oil. Not sure if us sportster guys can get away with that since we don't have separate primary and transmission oil, or if its ok to use gear oil on the clutch discs. Im sure others will chime in with better info.

 

A 75-90 Gear oil is not only fine in a Sporty, it is what's recommended. While HD doesn't publish any data on their products, Formula+ is an ~85 "weight" Gear oil.

You don't mention what this guy is riding. If it's a BT, then that's a different animal, and what he's running is not applicable to a Sporty. You shouldn't run anything "heavier" than a 75-90 Gear oil in a Sporty.

A 75-90 SAE Gear oil is NOT "heavier" than a 20w-50 SAE Motor oil, they are measures on 2 different scales, and are approximately the same viscosity.

 

Your right cHarley. I didn't say. He rides and Ultra Classic. Good information. Thanks!

 

look it up on the Amsoil site, they have a full line up and reference guide...

 

I always run formula + and never had an issue besides the crappy chain inspection covers and gaskets. I got the HD updates cover and gasket and no isses since. I'm not a fan of running heavier fluid to try to stop a leak.

 

Spectro Primary Fluid's the way to goooo.....in my bike anyway.

 

(01 Sporty 55k)I have been running Mobil 1 75w-90 in my primary for about 3 months now and at slow speeds (1st gear about 10 mph or so) I get a jolting sensation like the clutch discs are jumping. Is there an additive that I can use to change friction that the discs are experiencing? this doesnt feel exactly normal and doesnt feel like a low rpm rumble or shake of the bike.

Any thoughts?

 

How long since you adjusted the primary chain?

 

I just bought the bike this summer. It was pretty well maintained with everyday maintenance but not necessarily adjusting the primary chain. does the primary chain not have an auto adjuster for tension?