Gsx-r 750-85 Fuel tank

[suzukipojken86]

Hello

I have noticed that there are two types of fuel tanks for the gsx-r 750-85, one is flat around the fuel cap and the ather has an elevation arond the fuel cap.

Is there anyone who knows why??

//Robert

[Del]

The 85 750f didn't have that type of tank.

The only slabbies to have the raised section(like the slingshot tanks),were the Asian market(Australia/Indonesia/etc) and JDM(Japanese Domestic Market)Black/Gold 87 gsxr750h Jubilee ltd edition and Blue/white 750h Kevin Shwantz(same colour has his rgv500)special edition.
Some of the gsxr750rg ltd editons also had the 21ltr raised filler tank. 

 

Blue/white shwantz specail edition




Black/Gold 750h Jubilee ltd edition.


And the 86 gsxr750rg ltd 

[suzukipojken86]

Here is a swedish sold GSX-R 750-85 with the fuel tank, I hade it on my 750-86 swedish sold. And I bought a NOS tank with suzuki original partnumber for Gsx-r 750 -85 with that bump on it.  Can it be like some type of options?? (only speculating)

[Swiss Toni]

Mine's an '85F, Jap import...and no raised section around filler.

[Guest YoshiJohnny]

having a bit more in the tank comes in handy when making love to a beautiful woman...

[Swiss Toni]

Never a truer word, Paul!

[Roycee]

Never knew that thanks

[bernardo]

Same as  Swiss Toni, I have an  85F Uk model . flat tank

[markfoggy]

It is a development from the Endurace world BTW. The tank has the raised flange around the filler to acommodate twin fillers. The raised section at the front of the tank with the breather is there to help with fuel surge on a full tank. 

An Endurance tank brims at 24 lt and will fill to the top of the fillers using a dump tank. The problem then becomes what happens when you wheel a bike on to the grid on a hot day, expansion will try and throw all the fuel out of the one way valve in the breather line and dump it into the expansion bottle. Now in an ideal world, that fuel in the expansion bottle will syphon back into the tank as the fuel load comes down.

The real issue comes under very hot conditions, think Suzuka, Malaysia or S Spain, during the race. When you dump cool fuel into a superheated bike you shock the tank smaller, fill the tank to the brim. Then you go barrelling into that first corner with a fuel load that is rapidly expanding and throw all of it to the front of the bike. Fuel overflow bottle overfills and you end up with fuel exiting out from under the front fairing all over the front tyre and a hot engine.

So, a void above the fillers is a great idea. More modern Endurance bikes have a bit more give in the tanks, fuel injection is a lot more forgiving as you are pumping at regulated pressure and can therefore run secondary breather one way valves, tank mounted, not just in the overflow line. Try to run those tank internal pressures to carbs and you risk flooding the thing and pushing fuel out of the float bowls, all over a hot engine and the back tyre.

 

Edited October 19, 2016 by markfoggy
Woops, for clarity.

[Nik]

My original Swedish 1985 has a flat top. It was replaced in 1986 with new original tank from Suzuki and this tank was also flat. However, my mate's original 1986 has the elevated section around the filler. I have another 1986 tank without the elevated section.  There seem to be no logic around this.

[suzukipojken86]

Here is the part number 44110-27A01-13L, I think that 13L is the color code, it was painted silver, 

 It holds as much as the flat tank, 19 liters

[Slabby11]

This has been raised on a variety of forums over the years without any clear answers and as soon as someone states 'This year / that market' they get shot down. I have a black/red JDM raised tank and a blue/white UK raised tank so there always seems to be exceptions, its also confused by imports. I'm not convinced it really matters, just getting a solid one these days is difficult enough.