After reading a number of threads about ATF in the primary, I gave it a shot. I have run Harley's primary / transmission fluid in the primary since I bought the bike, and to be honest, the bike has run just fine. But I can honestly say this is the first fluid change I have ever done to a motorcycle where I could say.....DANG, that actually made a HUGE difference. The difference in finding neutral is truly like night and day. And the bike shifts threw the gears noticeably smoother. Don't know why, but this ATF trick is a huge improvement over the Harley primary fluid I have been using. The other very noticeable attribute is the bang my bike always had on that very first drop into gear if the bike sits overnight or longer. That pretty much vanished. Now, for people not running Harley's primary fluid, you may already have a great fluid and ATF might not do a thing, I am only saying that the improvement over the Harley fluid was huge. And I for one would NEVER have believed a different oil in a single hole on a motorcycle would have made a truly noticeable difference, but I swear to God, it made a huge difference. And all for $2.69 since I bought the cheap generic Auto Zone Ford ATF just in case this ATF trick turned out to be bunk, and I wanted to dump it out right away without being out any real cash. Just wanted to share my experiences.

Just a funny side note: I happen to have a see-threw porthole in my primary cover, and bright red primary fluid sloshing around is a funny sight, to say the least.

 

The viscosity in ATF generally is too low to recommend for using in the primary case.

 

Great to hear it's better.I'm gonna give it a shot.

 

I use Belray gear saver 80w. Same stuff that is used in the gearbox of my motocross bike. It looks like ATF fluid, being red.

 

it's what I use too

 

I was/am under the impression that atf fluid, or any fluid with additives would make the clutch slip. But maybe im wrong since Automatic transmissions have clutch packs in them.

 

How can ATF in the primary help something that takes place in the transmission?

 

Just the question I was going to ask.

 

ATF, being thinner and designed for use with clutch paks, allows the clutch to disengage more fully and the transmission to shift more smoothly. High viscoisty oils create a 'drag' when the clutch is disengaged.

I like the 'idea' of using ATF in my primary. It IS designed for use with clutch paks. But there's more going on in the primary than just the clutch. There's the primary chain and bearings and tensioner shoe and other stuff, too.

Many aftermarket clutch makers recommend the use of ATF with their clutches. But they're not concerned with anything other than the clutch they sold you.

I'm going to shy away from it until somebody convinces me otherwise. The low viscosity of ATF has me concerned.

 

Used synthetic ATF at the previous fluid change. Worked fine. This time I went w/ Rotella T, as it's JASCO rated. $3.19 / qt at wally world.