TANKS: 550 vs. 650 Maxim

Consider this my stupid question of the day:

I bought a tank off eBay, offered as a 550 Maxim tank.

Got it in today, and golly-gee does it sure look identical in size, shape, etc. to a 650 Maxim tank that I also have here.

Are there any tell-tale signs to tell these tanks apart? Fluid capacities? Anything?

Thanks.

 

I don't know.... but I have 3 1980 650 Maxim tanks here and they all look the same when you look at them seperately but when I put them together there are very small differences between them all... I'm not sure if it's because 2 of them have been damaged, but there appear to be some subtle differences in the shape of them.

I will take some photos later to show you what I mean.

 

Are all the tanks the same size (liter's wise). I have an 81 XJ550 Maxim and was wondering if i could get a bigger tank as the one i have is only 13 liter's. Most of my friends have new bikes and they are in region of 17-20 liter's. It seems that they always have to stop for me to refuel.

 

Maxim 550's and 650's tanks are identical - same shape, size, and capacity.

The only way to get a bigger tank is to go with a 750 Maxim's tank -- it's 19 litres as opposed to our 13. It's a direct fit too - no mods needed.

 

I actually think the 550 and 650 tanks are a little bit different...the 650 is a little bit longer (about 1-1/2" overall) and a little bit fatter (especially up in the front at the gas cap area circumference). And although they might swap between the two bikes, the distance between the front round rubber mounting "doughnuts" and the rear oval mounting pad opening is also different.....the 650 Max tank is about 1-1/2" longer in this dimension than the 550 Max tank, so although it would probably "fit", a 550 max tank on a 650 frame would be "barely hanging on for dear life" up at the front mounts, and the 650 tank on a 550 would require some major surgery either at the rear mount area OR would require the front doughnuts to be shaved WAAAAY down for it to even come close to fitting.......

At least that's what I have determined by simply MEASURING the tanks. I have not attempted a physically install & verify all of the baove, because I don't have a 550 Max here.

 

You are correct. I bought a 650 Maxim tank and tried to put it on my 550 and it doesn't fit. It looks very similar but the front mount openings are farther forward than on the 550.

 

Sanoke....did you try modifying the the front and/or rear bushings on the 550 to get that 650 tank to work? Were there any other interference or fit problems with the 650 tank, handlebars hitting at full turn, etc.? If you still have the tanks, and don't mind experimenting a little, I think it would be really useful info for people to have.....I believe that the 650 tank does hold more fuel than the 550 tank, and it does have that slightly fatter look than the 550 tank, so it would look better on a 550 if it could be made to fit.....

I think the way to do it would be to place the 650 tank in the proper position on the oval rear mounting pads, and then see how much material needs to be taken off the front mtg. doughnuts to make the 650 tank fit.

If that method presents a problem, then fit the 650 tank onto the 550 with the front rubber doughnuts in their correct locked position, and let us know how much of an offset there is on the back mounting pad. It may be that a simple offset rear mounting plate can be made to allow the tank to be fitted in that manner. Also be sure to check for rear-of-tank-tofront-of-seat interference issues.

The 750 tank would fit if the 650 tank would; however, it might look simply huge on a 550.