'47-'49 gas tank differences

[exeric]

I was talking with a friend last night about a set of tanks he wants to use on a '47 BT, but they have the characteristics of a '48 BT. The following link clears up most all of his questions.

Tanks - AMCA Forum (antiquemotorcycle.org)

[BigLakeBob]

It's strange you brought this up because I watched a You tube today with a guy selling an orig '48 and he mentioned the gas line offset, but shouldn't '50 be included here also?

[exeric]

That was the conversation with my friend. It's my observation that the '47 tanks are unique, and one year only, so I think '48 and later gas line locations and general tank configuration for rigid frames were the same (excluding tank badge types). . . Probably wrong, but that's what a forum is all about

[BillyBalcer]

40-47 OHV Gas crossover lines are the same and spacing is the same.
40-48 BT SV "Flatheads" Gas Crossovers are the same and spacing is the same.
1948 OHV Gas Crossover line is the same spacing as 49-65 However it is a one year only gas crossover and features a loop in the center.
1949-1956 OHV Gas Crossover line is the same spacing as 48 OHV. I believe the change in the bend had to do with the horn being moved to the downtube of the frame instead of on the springer. the spacing remained the same.
The factory never changed the part number for the -48 OHV fuel crossover. However there are 3 completely different bends. Each later bend would work on an early bike. Just not correct for the restoration guy who wants it how it left the factory.
Hope this helps in some way

Billy Balcer
AMCA #4040
Lake Erie Chapter- President
Strange Bird MFG.

[dukekleman]

1947 to 1950 Tanks as we know have the same badging.

However 47 tanks do not have the same relief indents as 48-50 tanks due to their different engine applications.

48-50 Tanks have additional relief indents for the Panhead valve covers. I also believe the fuel cross over fitting on the right side tank is located differently from a 47' year group verse a 48-50 year group tank.

Hope this helps,
Duke

[Rubone]

And...there are factory tanks out there with both hole locations and a plug in one...
Parts order replacement?? Mid production change?

[MMasa]

Rubone
I have a set of tanks like that that came with my VERY low VIN 1948 project (under first couple hundred in 48)
I had assumed that it was an early 48 production thing where they could be used on either late 47 production OR early 48 production.
I’ve only ever seen 2 or 3 ever with both embossed nipple rings.
Mark

[Jerry Wieland]

1947 and 1948 UL tanks are different in the rear do to the difference on how the upper rear frame tubes are tied in to the seatpost and the upper frame tube. Putting 1947 UL tanks on a 1948 UL frame sometimes will rub and wear.

Jerry