And water cooled and I am sure other things, no?
What's the opinion on 2T vs 4T in trials?
In my experience 4T is a lot easier to ride overall, (better for an old guy) they sound way better and don't make the guy sitting behind you intoxicated from the synthetic oil fumes when you are sitting in queue for a section. They don't load up the silencer with oil residue that eventually catches fire and causes a smoke screen. The extra weight (~7 to 12 pounds) is noticeable but has never been enough to affect my riding ability at the intermediate level. 4T power delivery is very broad by comparison and most noticeable advantage is on slime mud sections and long slippery hillclimbs. You Have to be smooth on the throttle compared to a 2T, they don't like to be blipped a lot like people habitually do on a 2T! Blipping the engine plays havoc with the fuel injection, valve train and your traction. While they do get considerably better fuel range, fuel injection likes to have lots of fuel in the tank to keep the fuel pump cool, so you end up re-fueling just as frequently. Beta 4T uses a carb but you can tell it has a carb when you ride it, otherwise imho it is the second best 4T on the market, the rest of them I would not want, so the 4T market is basically a Montesa/Honda. On a 4T to get the explosive takeoff acceleration like a 2T has you have to rev the snot out of them and drop the clutch.
2T's are like a rocket ship on takeoff, their power delivery is earlier and they are easier to hop as a result of that. In the hands of a top Expert rider the 2T is potentially a more competitive ride, assuming it is Not a no-stop event. The lighter weight makes the bike a little easier to get airborne or hop the front or rear around. The TRS 300 is an amazing easy bike to hop around on, it's light, it's powerful, the suspension and weight distribution is awesome and it has so much freakin compression combined with a short kick start throw that I can't start it, otherwise I would probably want one. Beta and Sherco are the nicest 2T's imho GasGas makes or did make a respectable 2T but you have to keep the bottom end seals perfect or they start working like crap. All of 2T's need the reed valves to seal perfect or they start working like crap. Ossa, do they still make Ossa? they perform great when they are working great, but the brand went through a Lot of changes, they introduced some um :/ unique features that may or may not work so good, for a while there people were messing with them a lot immediately before a trial. ... usually to get them started. If you have one and it starts good and runs good, I recommend you don't mess with it, just ride it. Weight distribution is amazing low to the ground.
Water cooled is nice because they don't sound as ratty and because they are less affected by over-heating but it's not a deal breaker, pretty sure all 4T trials bikes are water cooled anyway. The only air cooled 2T trials bike I owned was a Yamaha and the water-cooling wasn't a shortcoming the problems were drum rear brake, slanted bash plate and the high mounted shock absorber makes it more prone to flip out when you get it vertical. ... I find linkage type monoshock rides to be superior.
The thing I don't miss the least about vintage/twin shock bikes is not having the insides of my legs bruised and smashed by the shock absorbers! and most of them carry about 15 pounds worth of fuel which is excessive for a trials bike. Front forks on older trials bikes are terrible! The best upgrade you can do to a vintage Trials bike is install modern 2 ply radial gummy tires on it and ride it as your second bike. Riding a modern bike as your first bike will make you do things on a vintage trials bike that you would have never though to even try.
gee, I wrote a lot, I hope that is not too much information!