Kind of limited info ,but if the problem is the tank, and not the frame rails, you could use spacers and longer bolts and lift the rear of the tank. Keep in mind that this will limit your reserve fuel unless you also lift the front of the tank , either or both would be much simpler than relocating the carb. Welcome!

It should work better than you think ,the distance from the motor should give the flow time to straighten out before entering the intake passage in the head, and an  elbow will not have any ill effect. the actual length from the air cleaner to the intake valve will, you should research intake tuning to understand why. the TM-40 is larger than a 36-38 and may favor a bit shorter intake.

Fantastic ! Thank you guys so much, that is all I really needed to know. I'll look into the intake tuning to see what would be good. I have time yet. When my rings get here ( OEM ) I'll be putting the bike back together. I'll show some photos and try to give some info as to what I did. Much appreciated !

On 4/5/18 Lancer wrote:"Whatever you build, whether from steel or aluminum, must be hard mounted or the engine vibration will mess you up and/or break the mounts.  You can’t just use thin aluminum and the flange must be metal as well, the rubber flanges allows too much vibration.  
Trust me on this, I know from experience."

I'm interested in this comment.  Lancer, can you please elaborate.  What sort of problems did you encounter?  What particular carb was involved?  The stock carb is certainly no lightweight and the rubber flange seems to handle that OK.  Did you ultimately end up using a solid flange with your swap?  I will probably need to fab a custom solid flange and am very curious about things like vibration effect on metering and float ass'y, heat transfer and fuel percolation.  If you used solid, did you have to insert an insulator?

DragBikeMike wrote on 04/07/18 at 14:22:37:



The reason for saying a solid mount is needed was because I tried 2 different carbs, a Quicksilver and a VM, both essentially the same weight.  The mount used was the standard rubber flange with a PVC elbow, and I also had an aluminum piece brace the top of the carb to the frame tube, but then had to switch to a steel piece.  Both ended up breaking due to the vibration that was allowed by the rubber mount flange.  The only way to avoid that is to make or get an aluminum flange and weld an aluminum elbow to it and attach the carb to that, giving a strong solid mount that should eliminate the vibration problem.  I have some pieces to use but have been preoccupied with an assortment of other things and so have yet to get it welded up.
I have one frame that was modified and that mod required the carb to sit outside the frame; that is how this all came about.

You could also use steel but I just wanted to try aluminum first.

DragBikeMike wrote on 04/15/18 at 20:05:57:


The small brace that I had attached to the top of the carb did a good job of stabablizing the carb until the material failures occured.  It shook so much that fuel could not effectively be pulled from the bowl.  Running got really rough the moment it let go.  We were riding in the Smokey Mtn’s on The Tail of the Dragon and it was several miles back to the hotel and it just kept getting worse as I tried to keep it going and it died as I started the final downhill run to the hotel so I just coasted in.  
I did NOT want to have to push it up and down the hills.