Originally Posted by Scott Fisher

OK dude. You asked for it. First, I didn't say the X12 isn't a long stroke. Yes the X12 is a long stroke. Its stroke is longer than its bore. The LL is a LONGER stroke than the X 12. So when compared to each other, the X12 has a shorter stroke than the LL.

The same piece of paper that you looked at calling the X12 a long stroke engine also will tell you if look closely that it is an NS12. If you still want to not believe me, look at the exploded view with the parts listing. They are the same. Same piston, sleeve, rod, crank, bearings, etc. Same bore, same stroke. I'm sorry, they are the same. Still don't want to believe me... Call Mugen and ask them. Forgot, they have a different cylinder head.

The N12 LS3 is the new long stroke. The N12 LL3 is the new LONGER stroke. The LS replaces the NSR which replaced the NS. The difference between the NS and NSR was the microcast piston/sleeve. When they went to the LS they changed the sleeve.

The LL replaces the RR12L3. The LL has a different sleeve.

Feel free to go to Novarossi's website and download the parts list and compare them to the Mugen X12 parts list. I was not trying to be a jerk, but simply correct inaccuracies. The differences you see in your engines may be in tuning or just your perception.

The LL is quite different than the X12. Different piston, sleeve, and crank.

Finally, the general difference. As you increase stroke, you increase torque. As you increase bore, you increase RPM. The RR and LL engines are torquier, and the NSR/LS is a more revvy (yeah I know that isn't a real word) top speed engine. The simple reason is as follows. Shorter stroke, the piston has to travel a shorter distance to complete a cycle. This makes it rev easier.