What's this bike then?????

[BaZa®]

Answer to follow:

[harleyshrew]

Its an old harley davidson

[Steppenwulf]

Is it region 13's new telescopic flag pole carrier?

[Jeb]

It looks like HD's attempt to dissuade tailgaters, ie a 'Kin big cannon pointing backwards!

[dantheman]

a cracker ,and could i borrow it next time i make the school run

[Ultima Tony]

With the ever increasing rise in petrol costs, is it an alternative fuel Harley Davidson?
Basically you just squeeze the trigger and hang on for dear life.
Note that there are no need for rear view mirrors as no one is likely to be following you on that one.
Apparently it does 10,000 bullets to the mile.

[Ukkid76]

It would be handy in Italy the Italians wouldn't sit two feet from your rear bumper with that staring at them

[Brigg]

Could be the recoiless rifle model

[rich16]

Is it a US Army Harley UA?
I've heard of a backfire but that's a bit over the top

[kevscrivener]

Originally Posted by rich16

Is it a US Army Harley UA?

Model R or early WL Rich, chain drive on right therefore not a U. Early WL more likely as it seems to have ally heads.

My guess is either 35 or 36, think they went over to "beehive" rear light in 37. The white speedo dial and handlebar grips may well indicate it's a civilian model?

Not sure about the gun but I'd hazard a guess it's some kind of light anti-tank or anti-aircraft gun.