New engine in AT

[africajim]

I looked at that black one in Willie Young motorcycles and was taken to one side and told "don't, it's sh*te! Feckin Aprillia, don't touch it!"
@T with a VTR engine? That's just a Varadero. Agreed, a good bike. Nothin out there that appeals to me that much, I'm not really a BMW fan so no 1200 for me, I'd rather the 800 personally but would prefer a Honda really.
In all honesty I love my Varadero and wouldn't want to change it this yr so plenty of time to have a look around.
I loved my @T, but better seat, more power and a six speed box would have made it a better bike, the Vara comes closest to that criteria for me.

[raymo]

stick that x990 in an @ mmmmmmmm

[Sully22252]

I would have always liked a lot more grunt and maybe another 10 bhp from the AT but the existing engine is tight enough in the frame so there's not much room to play with. Basically a 90 degree V-twin isn't going to fit, it needs a narrow angle V-twin, the current engine is only 52.5 degree, and is fairly short as its only single OHC.

Just maybe a narrow angle short stroke V-four would fit, but I think it would upset the balance of the bike off-road due to the greater engine width and also wouldn't have any bottom end grunt which you really need if you are ever going to use it off-road.

The basic engine design used in the AT has appeared as a 500, 600, 650, 680, and 800 (Pacific Coast) and two 750's, the AT and the Shadow. The Shadow has the same bore diameter as all versions of the Transalp and gets its 750 capacity from a long stroke crank. The AT is the odd one out as it has the biggest bore of any of the engine derivatives.

I've no idea of the practicality of this, but if the long stroke crank from a Shadow could be used, probably with Shadow barrels bored out to take AT pistons, and AT heads, you'd get something like an 840 cc engine, only a few MM taller, but most importantly, with the longer stroke you should get a lot more low down grunt plus a few extra BHP. Just dreaming really, but if I could afford to butcher a couple of engines I'd love to give it a try.

Attached is a picture of another engine with most of the attributes for a good long distance adventure bike, pictured between Douenza and Timbuctu in Mali. Only 65 bhp but all the grunt you could ask for and amazing traction in soft sand, plus would cruise happily all day at 80+.