No running when putting a load on it

[Flattsix6]

I have a 1500 Valkyrie it runs fine at idle but as soon as I put a load on it try and go down the road it bogs down can anybody help me with how to diagnose this maybe this happened to somebody else

[Pluggy]

The engine may be getting enough fuel to idle but not run powerfully. An easy first step is to remove the tank and the valve. Check the filter screen by removing it from the tank. Then open the vacuum side of the valve and see if the diaphragm is damaged or out of shape.  The diaphragm is the most likely part to fail, and can be replaced. The "manual side" of the valve can fail and it is more difficult to repair. 

Installing a new valve is easy.  Owners will advise you to avoid the eBay knock-offs.

[WintrSol]

How much time between start and ride? Carbureted bikes need some warmup before you can expect more than gentle acceleration.