Fitting Alloy Tank to MX250A

[mposs]

Hi All,
          I am hoping someone may be able to guide me a little. I am building up a 1974 MX250A as a race bike and would like to fit the MX250B alloy tank that I have. My question is would you reposition the mounts on the tank or move the mounts on the frame to suit the tank?

Cheers Mark

[Tossa]

I remember when i built my MX250A, it had had a long range plastic desert tank on it, the actual tank mounts had been removed, found it easy to have mounts repositioned on the frame.  So my solution is shift the mounts as they are easier to reposion than tank mounts, well worked for me.

[cyclegod]

I always thought they went straight on the existing mounts? are you trying to move it forward or lower or something?

[YZ250H]

What about another picture from another angle like the top one so we can see how far away/where the mounts are ?  Looks like it fits well from the top picture.
I think I'm with Tossa on this one.  Easier to move the mounts on the frame ? At least you don't have to buggerise around welding alloy (?)

[mposs]

Thanks for the replies.

As you will see in the photos it appears that the tank mounts will slide into the standard frame cups. The issue is that the tank hits hard on the main frame backbone. It appears that the mounts on the frame need to be raised about 20 - 25mm to allow tank to clear frame and sit down correctly at the rear mount.

[Tossa]

how close is it with the rubber mounting pieces on the tank.

[firko]

how close is it with the rubber mounting pieces on the tank.

My thought also. If it's only just touching the frame, a bit of boilermaker ball peen persuasion to the area where it's rubbing might give you enough clearance. Once in place a piece of rubber packing would also ensure the tank won't eventually wear through due to metal to metal contact.

If you're a bit worried that your hammer technique might damage the tank, search out an old school panel beater who knows how to use a hammer and dolly and he'll easily be able to relieve the problem area.

[vandy010]

i agree with firko {g'day mate},
if it's a close fit, a bit of gentle tapping with a ball pien hammer underneath the tank should work.
if it's close to the filler cap it may mean you'll have to fill the tank slowly though.
i'd also fit the forks first, just to make sure you've got clearance there too before you go too far.
if there's issues with fork clearance as well, then i'd be looking at moving the mounts.
all good fun

[Freakshow]

Whats happeing at the back ? have you removed the rear mount or what the plan there that will also influence things i would have thought.

[mposs]

Hi All,
         Thanks for the input. In answer to one of the questions the rear mount has been removed and another is being fabricated to suit now that I have repositioned the tank. As you will see in the photos I took the advice given and removed the cups from the frame. I also ground off the raised area that located the standard mounts and  fabricated new plugs and welded in to the remaining holes. The relocated tank mounts are now both higher and rearward on original. The last picture is the final position of the tank, now it is time to repair and repaint tank.

Cheers Mark

[YZ250H]

Looks Good Mark 
Well done