Answered: Why So Many Single Cylinders?
 

This week we get into why the single-cylinder engine still reigns supreme in the off-road arena:


https://atvconnection.com/articles/a...nder-machines/

Its basically the last part, lower cost. Twin cylinder machines cost more. They cost more to develop and build and cost more for the buyer. Generally the twin cylinder(some even 3cylinder) machines are the higher end top of the line models. Single cylinder machines are powerful enough for most. Muliple cylinders give you that extra performance that the higher end buyers are willing to pay extra for. There are a few machines like 4 seater utvs that are so big and heavy that multiple cylinders are almost a must though. Some of them are almost as heavy as a very small car empty and then add 4 adults or more and fill the bed and you would really have a single cylinder engine working hard just to get moving.

Despite their disadvantages twins do have an advantage that wasn't mentioned. At least, one of them did. When Polaris came out with the 600 twin, which wasn't an H.O., it only had 8% more horsepower than the 500 H.O., but it had 25% more torque. Not bad for a low output engine that's only 20% bigger than the high output 500. There are times when all that extra torque could come in handy. If the 600 was an H.O., who knows how much more torque it would have than the 500 H.O.? Probably 30% more torque from 20% more displacement, only because it's a twin.

The only disadvantage I see to twin cylinder machines is cost. Everything else is a positive. Even fuel economy doesn't vary much except the older Kawasaki v-twins with the dual carb setup. Those things gobbled fuel. Pretty much every new atv has efi and even the 1000cc twins still get respectable fuel economy.