I notice the Foreman/Rubicon motor is ligiud cooled now vs Air cooled but they still have the same displacement of 475 and bore and stroke of 92 x 71.5 mm and is still a OHV. 2011 Honda FourTrax® Foreman® 4x4 ES (TRX®500FE) ATVs If you hit "Detailed spec" at the bottom of photos the new one is a 33mm throttle body(EFI) and the older is a 33mm carb.

Is it just the same 475 motor with a water jacket cylinder with a rad added on now?

 

I would assume the new Rubicon engine makes a little more power than the old air-cooled one. I have read it is more responsive than the older one. Is it the same engine with fuel injection added? I don't really know. Fuel injection will make an engine more responsive. I do know that it took forever for Honda to decide to put fuel injection on that engine. Everyone else had been offering fuel injection for several years and Honda finally realized that they had to do it on the Rubicon. I think Honda should drop the Rincon completely and simply build a more powerful Rubicon as their flagship model. It already has efi, power steering, diff-lock, irs and the dual-clutch 5 speed automatic transmission. Not to mention, its the best looking machine Honda has. All great features, it just needs a powerful engine to add some go to all that show. Perhaps a scaled down version of the new Pioneer 1000 v-twin. Something in the 750-800cc range at least making around 60 hp or more would be great. That would put it above the Grizzly, Brute Force and King Quad 750 and about equal to the Can-Am Outlander 650.

 

I know efi added made little difference on the 500H.O , the carb motor was 35hp while the efi was 36hp. In Honda case they also made the 475 into a ligiud cooled from a air cooled.
The old school OHV remained so it can't be a power house over the older air cooled version.

 

I think the engine in the Brute Force 750 now is the same as it ever was just with efi added. But it was already a great engine. Efi probably helped make it a little less finicky by eliminating the dual carbs. In the Grizzly, Yamaha built an entirely new motor to replace the carb 660 engine. The first version of the 686cc was only a marginal increase in hp than the 660 but it is noticably more responsive. I think the biggest difference is the increase in fuel economy over the 660. I would guess its about 25% more fuel efficient. For me fuel ecnomy isn't that big of a deal most of the time. But I can see where it might be important if you were say riding a long trail loop like on the Paiute Trail or some of the Hatfield-McCoy trails. The fuel range becomes an issue then. I estimate my Grizzly would get about 80 miles out a full 5 gallon tank. If I wanted to make some of those really long 90-100 mile loops, I'd have to take extra fuel along. The Grizzly 700 would make a loop like that and still have some fuel to spare.

 

I'm into sleds, foremost .I thought ATVs sip gas in comparison.

 

By comparision I suppose they do. The newer fuel injected quads all benefit from better fuel economy than the older carb ones. If I actually rode long enough to actually empty the gas tank I think I would be begging for a break anyway. Even at a relatively brisk 20 mph average speed, it would take 4 hours to run my Grizzly out of gas. 4 hours is a pretty long ride.

 

The new 500 motor is just that. It has far more in common with the 420 engine than the old air cooled 500.

Anyone who thinks fuel injection is better wants to try fixing them when they go wrong. I've got a Suzuki 400 that won't rev above about 2500RPM and spent hours going through the FI system, including changing every component, including the ECU. Still no better. Concluded it must be something else so took the cam cover off to find the cam lobes worn out. I would have eliminated the fuel system hours earlier on a bike with a carburettor. ATV makers are still playing at fuel injection, without oxygen sensors their systems are just spray fuel in and hope, like carb systems.

Fuel consumption is important to people who use them for a living, particularly in Europe where petrol prices are round £1.20 a litre, about $7 a gallon.

 

I suppose you have a point there. Carbs are much easier to work on. The inconvenience of having to pull a choke and let a machine warm up when cold isn't really that bad I guess. That's the real advantage fuel injection has, instant start up. I can imagine its much harder to diagnose and fix problems that arise. And a lot more expensive for customers too once the machine is no longer under warranty.