Whats the main difference between the 2 valves & 4 valves ducati's Thanks
2 valves...
There are about a million threads out there that compare the 2 valve and 4 valve engines. Basically, both bikes are very reliable but the S4 is less reliable because there is more that can go wrong. It requires a little more intensive maintanance and more costly maintenance. But the 916 is a very good and reliable engine. Here are some searches that have some interesting results: