Primary oil change question
Outstanding HDF Member
Joined: Apr 2007
Posts: 2,272
Likes: 279
From: .
There is no other way to fill the primary and/or check the level - you HAVE to remove the derby cover.
The gasket is reusable until it starts to leak. I always keep a new one on the wall for that reason. I get mine from a local independent shop (cheaper and just as good).
The gasket is reusable until it starts to leak. I always keep a new one on the wall for that reason. I get mine from a local independent shop (cheaper and just as good).
Outstanding HDF Member
Joined: Nov 2008
Posts: 2,246
Likes: 19
From: Cypress, TX
I used the same gasket on my last bike for at least 5 oil changes. I changed the primary and tranny every 10,000 miles. Engine at 5,000. Never leaked. It was an '09 (no inspection cover) and I used the old style gasket instead of the o-ring since I changed derby covers. That little funnel Harley sells to fill through the Derby cover opening really makes it easy.
Outstanding HDF Member
Joined: Jan 2008
Posts: 3,328
Likes: 15
From: Pacific Northwest
I too have an 88" motor (actually a 95" now). The primary is best filled through the derby cover (as recommended by the shop manual).
Although re-filling through the 'inspection cover' (the one for adjusting the primary chain tensioner) would not be entirely impossible, it would be very awkward since it is well below the level of the oil. It would require laying the bike nearly on it's side.
I agree that an inspection cover on the later motors would be a welcome addition. It would be pretty handy for checking the automatic ramp tensioner.
Seasoned HDF Member
Joined: Nov 2010
Posts: 17,548
Likes: 7,197
From: Oxford, Nc
I too have an 88" motor (actually a 95" now). The primary is best filled through the derby cover (as recommended by the shop manual).
Although re-filling through the 'inspection cover' (the one for adjusting the primary chain tensioner) would not be entirely impossible, it would be very awkward since it is well below the level of the oil. It would require laying the bike nearly on it's side.
I agree that an inspection cover on the later motors would be a welcome addition. It would be pretty handy for checking the automatic ramp tensioner.
Although re-filling through the 'inspection cover' (the one for adjusting the primary chain tensioner) would not be entirely impossible, it would be very awkward since it is well below the level of the oil. It would require laying the bike nearly on it's side.
I agree that an inspection cover on the later motors would be a welcome addition. It would be pretty handy for checking the automatic ramp tensioner.
Road Master
Joined: Apr 2012
Posts: 826
Likes: 0
From: Phoenix
I can never tell where the level is so I just put in the recommended amount per manual. I have used the derby gasket several time without replacing. The inspection hole it just as easy to fill the primary, but also has a gasket.
Outstanding HDF Member
Joined: Jan 2008
Posts: 3,328
Likes: 15
From: Pacific Northwest
I don't know what bike you've got, but the bottom of the inspection cover is about the same height as the derby cover on early TC FLT "short" primaries.. The oil can be filled through either opening and neither will spill even with the bike resting on its side stand. (About 1 quart on an '04 if memory serves.)
My bike is an '06 Street Glide.
Problem is, the bottom of the inspection cover is 3/8" lower than the bottom of the derby cover. With the bike on it's side stand, primary oil spills down on the floor if it is not drained before removing the inspection cover. (I found this out the first time I tried to adjust the tensioner without first draining the primary.)
So....re-filling through this cover isn't impossible, just unnecessarily difficult when the derby cover is so very easy to use (and spelled out in the shop manual as the correct method).
And with that reply I think this horse is now quite dead.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Ultimate HDF Member
Joined: Dec 2006
Posts: 5,878
Likes: 17
From: The Desert SouthWest
I change the gasket maybe every 3rd or 4th time. I've never had one leak before actually.