well the jumps not to hard
you say you got 2wd but its weak? umm interesting
well obviously sprocket and new chain is needed and then you have to have a off set of the wheels for the chain, and then you must align it all, the jumps very doable but you come across other problems
well depends on your wheel choice really but once you make the jump you be working on Tank drive and if your wheel base is to long then you wont be able to turn at all and if you have high traction wheels you wont be have to turn at all you'll just be dancing around all over the place and thats bad thing lol
everything you all ready have but double it that the difference
more weight
more traction
more control
more work
but the jumps worth it if you can get it to turn right if you don't have high traction wheels then you should be fine as for the weak drive you might consider different gearing if thats possible
but the 4wd should be able to provide much more go on your bot
-Oscar-
Tell me how it works out