The Harley Davidson Milwaukee 8's issue of transmission fluid migration from the transmission housing into the chain case , in my opinion , is nothing new.
For a start , the engine has nothing to do with the problem , it's a transmission issue !
I have a 2013 Fat Bob (103 inł ) and I started to experience this problem well over 18 months ago.
I checked my transmission fluid one day and it didn't even register on the dip stick. There were no traces of a leak on my garage floor or under the bike itself so I rang my local Harley Davidson dealership and told them what had happened . They advised me to bring the bike in so they could check the levels and top up accordingly (they did this free of charge).
They advised me to go away and bring it back 500 miles later .
After about 100 miles, I checked the transmission fluid and once again , it had dropped. I realised that I could not continue to ride until I had covered the 500 miles , so I topped it back up.
Another 100 miles and another drop.
All this time engine oil level remained normal so there was only one other place the fluid could be going !
I removed the chain case and a LOAD of fluid came out !
Next thing was to try and find out how it was getting in there !
I studied the illustrations in my manual and decided through a process of elimination that the fluid was most likely getting past the clutch pushrod.
I went for a long ride and checked the fluid when I had got home and after the engine had cooled , only to find that there had been NO fluid loss at all !
It was now obvious that the problem was occurring during the time my bike was in its shed .
Since I had another small bike to squeeze in the shed alongside the Harley , I would store the Harley with the steering turned fully to the left with the bike resting on the twistgrip against the inside of the shed.
The transmission never lost another drop of fluid after that day !
My assumption is that knowing the chain case relies on the clutch pushrod for vent to the atmosphere , by leaning the bike to the right instead of on the jiffy stand , the right hand end of the pushrod is immersed in the transmission case's lube oil. When the air in the chain case cools after a ride , it contracts and so creates a vacuum which in turn 'sucks' fluid through from the transmission ! The transmission case , as we know , is vented via its own breather pipe.
As weird as this sounds , I can't see any other explanation !
Regards.

 

I don't know either way,

has anyone experienced this issue that parks their bikes upright in the garage?

 

 

Things that make you go "Hmmmmmmm...."

 

 

There are very few that have reported the problem on a cable actuated clutch bike. So, you quit parking the Harley leaning to the right and the transfer stopped. That is a little different than what is happening with the M8 hydraulic actuated models. The main difference is, you actually figured out why and how it was happening and could take steps to prevent it. I can prevent it on the M8 hydraulically actuated clutch models, but I can't definitively tell you why or how it happens. That part of it is still somewhat a mystery. I can tell you though that it does happen while the bike is being ridden because there are in severe cases incidents of the transmission fluid levels dropping dramatically in less than a hundred miles of riding.

 

How do you prevent this happening on an M8 ?
Is the old clutch actuating mechanism not just replaced by a slave cylinder ?

 

 

I just read your problem I just checked the trans dipstick in my FLXHS and it's dry

 

Marty, forum police are going to get you (per forum rules you need to first post an introduction in the Welcome Area). Also, there are about 100 threads discussing the transmission fluid migration issue and resolution. 3 on the first page of the Milwaukee 8 section