Evo Softail gas tank capacities
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Intermediate
Joined: Jun 2025
Posts: 26
Likes: 14
From: Utah
I am 99% sure that the original Springer Softails came with tanks smaller than the Softail Customs. Now were they 3.5 VS 5.0 or 4.2 VS 5.2, that I am not sure. But I would have bet a beer in a bar that it was the former. They made Softails for a long time, maybe this is a year specific question.
I think it is pretty safe to say that all Softail Customs had 5.2 gallon tanks and pretty much all other models had 4.2 gallon tanks. I believe the Heritage Nostalgia also had 5.2 gallon tanks though. I haven't really found anything conclusive that shows that any models came stock with 3.5 gallon tanks. I am starting to think people incorrectly assume the smaller Softail tanks were 3.5 because that is what the older panhead/shovelhead split tank size was, but in reality they are actually 4.2 gallon. It is possible this assumption started with the guy at Harley who was creating the parts lists, and that is why they all show 3.5 gallon and 5 gallon tanks for the evo Softails.
Anybody have any proof of stock 3.5 gallon tanks on a Softail?
Intermediate
Joined: Jul 2022
Posts: 41
Likes: 26
From: Earth
According to the Harley parts diagrams, the early Springers had the same tanks as the Fat Boy and the Heritage. Sometime in the mid 90s (I think 95 or 96) they changed the location of the petcock and moved it further back, but I believe the capacity of the tanks didn't change.
I think it is pretty safe to say that all Softail Customs had 5.2 gallon tanks and pretty much all other models had 4.2 gallon tanks. I believe the Heritage Nostalgia also had 5.2 gallon tanks though. I haven't really found anything conclusive that shows that any models came stock with 3.5 gallon tanks. I am starting to think people incorrectly assume the smaller Softail tanks were 3.5 because that is what the older panhead/shovelhead split tank size was, but in reality they are actually 4.2 gallon. It is possible this assumption started with the guy at Harley who was creating the parts lists, and that is why they all show 3.5 gallon and 5 gallon tanks for the evo Softails.
Anybody have any proof of stock 3.5 gallon tanks on a Softail?
I think it is pretty safe to say that all Softail Customs had 5.2 gallon tanks and pretty much all other models had 4.2 gallon tanks. I believe the Heritage Nostalgia also had 5.2 gallon tanks though. I haven't really found anything conclusive that shows that any models came stock with 3.5 gallon tanks. I am starting to think people incorrectly assume the smaller Softail tanks were 3.5 because that is what the older panhead/shovelhead split tank size was, but in reality they are actually 4.2 gallon. It is possible this assumption started with the guy at Harley who was creating the parts lists, and that is why they all show 3.5 gallon and 5 gallon tanks for the evo Softails.
Anybody have any proof of stock 3.5 gallon tanks on a Softail?
I wonder if the assumption started when owners ran out of gas then filled it up and it only took 3to 3.5 gallons. I cant speak for anyone else but anytime I had to hit reserve I didnt waste any time finding a fill up spot. It had gas in it when I picked it up from Harley so I probably never pumped more than 3.5 gallons into it until I first removed the tanks years later.
Im sure im in the minority because I still ride that bike 37 years later. So I can see someone making that assumption(3.5 gals)
Seasoned HDF Member
Joined: Apr 2010
Posts: 9,556
Likes: 7,904
From: Long Island, New York
Per OEM Parts Finder on the Harley Davidson Website:
FXSTS BLLK Softail Springer (1989) BLLK FXSTS Softail Springer (1989) Softail Springer FXSTS BLLK (1989)
61426-85C FUEL TANK LEFT, 3.5 GAL. (PRIME)
FXSTC BKLK Softail Custom (1989) BKLK FXSTC Softail Custom (1989) Softail Custom FXSTC BKLK (1989)
61238-90 FUEL TANK, left - 5 gal. (prime)
Heritage and Heritage Classic also listed as 3.5 Gallons. Softail Standard is 5.0 Gallons.
The Mother ship has spoken., small and large had the same capacities from the Shovelhead days, 3.5 and 5.0.
FXSTS BLLK Softail Springer (1989) BLLK FXSTS Softail Springer (1989) Softail Springer FXSTS BLLK (1989)
61426-85C FUEL TANK LEFT, 3.5 GAL. (PRIME)
FXSTC BKLK Softail Custom (1989) BKLK FXSTC Softail Custom (1989) Softail Custom FXSTC BKLK (1989)
61238-90 FUEL TANK, left - 5 gal. (prime)
Heritage and Heritage Classic also listed as 3.5 Gallons. Softail Standard is 5.0 Gallons.
The Mother ship has spoken., small and large had the same capacities from the Shovelhead days, 3.5 and 5.0.
Cruiser
Joined: Sep 2017
Posts: 119
Likes: 65
From: Atlanta
No, Not flat side or aftermarket, original bad boy tanks. The manual says 3.5 but in reality it may be 4.2 as many claim. I've never run it completely empty on reserve so can't tell you how much they actually hold.
Thread Starter
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Intermediate
Joined: Jun 2025
Posts: 26
Likes: 14
From: Utah
Per OEM Parts Finder on the Harley Davidson Website:
FXSTS BLLK Softail Springer (1989) BLLK FXSTS Softail Springer (1989) Softail Springer FXSTS BLLK (1989)
61426-85C FUEL TANK LEFT, 3.5 GAL. (PRIME)
FXSTC BKLK Softail Custom (1989) BKLK FXSTC Softail Custom (1989) Softail Custom FXSTC BKLK (1989)
61238-90 FUEL TANK, left - 5 gal. (prime)
Heritage and Heritage Classic also listed as 3.5 Gallons. Softail Standard is 5.0 Gallons.
The Mother ship has spoken., small and large had the same capacities from the Shovelhead days, 3.5 and 5.0.
FXSTS BLLK Softail Springer (1989) BLLK FXSTS Softail Springer (1989) Softail Springer FXSTS BLLK (1989)
61426-85C FUEL TANK LEFT, 3.5 GAL. (PRIME)
FXSTC BKLK Softail Custom (1989) BKLK FXSTC Softail Custom (1989) Softail Custom FXSTC BKLK (1989)
61238-90 FUEL TANK, left - 5 gal. (prime)
Heritage and Heritage Classic also listed as 3.5 Gallons. Softail Standard is 5.0 Gallons.
The Mother ship has spoken., small and large had the same capacities from the Shovelhead days, 3.5 and 5.0.
Seasoned HDF Member
Joined: Apr 2010
Posts: 9,556
Likes: 7,904
From: Long Island, New York
The FACTS are out there:
FXSTS 1BLL SPRINGER SOFTAIL (1999) FUEL TANK
61426-97 FUEL TANK LEFT, 4.2 GALLON (PRIME)
I am not spending the time to check every year for the change over, but Milwaukee started at 3.5 then moved up to 4.2. Why is all guesses. Fact per my posts, 1989 was 3.5, 1999 was 4.2.
FXSTS 1BLL SPRINGER SOFTAIL (1999) FUEL TANK
61426-97 FUEL TANK LEFT, 4.2 GALLON (PRIME)
I am not spending the time to check every year for the change over, but Milwaukee started at 3.5 then moved up to 4.2. Why is all guesses. Fact per my posts, 1989 was 3.5, 1999 was 4.2.
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Thread Starter
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Intermediate
Joined: Jun 2025
Posts: 26
Likes: 14
From: Utah
The FACTS are out there:
FXSTS 1BLL SPRINGER SOFTAIL (1999) FUEL TANK
61426-97 FUEL TANK LEFT, 4.2 GALLON (PRIME)
I am not spending the time to check every year for the change over, but Milwaukee started at 3.5 then moved up to 4.2. Why is all guesses. Fact per my posts, 1989 was 3.5, 1999 was 4.2.
FXSTS 1BLL SPRINGER SOFTAIL (1999) FUEL TANK
61426-97 FUEL TANK LEFT, 4.2 GALLON (PRIME)
I am not spending the time to check every year for the change over, but Milwaukee started at 3.5 then moved up to 4.2. Why is all guesses. Fact per my posts, 1989 was 3.5, 1999 was 4.2.
Is that because they just re-used the same part number for a new (larger) tank? Or did they finally realize their mistake and start listing it as 4.2 in the 1999 parts lists? There was another part number for the left tank (61426-85C) that was used on the earlier Springer, Heritage, and Fat Boy models, I think up until about 95. The petcock is in a different location but according to posts here, it sounds like they were also 4.2 gallons.
Thread Starter
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Intermediate
Joined: Jun 2025
Posts: 26
Likes: 14
From: Utah
