I know this may be a silly question, but after riding a 2006 Polaris Sportsman 500 efi I'm just not impressed with the power of these smaller displacement 4 strokes(ride comfort and handling is great though). I currently have a 1994 Polaris 400L 2-stroke. Perhaps it was just the plushy ride of the Sportsman, but it just doesn't seem to have the throttle response or acceleration of its ancestor. I know the hp numbers are similar (35ish). The only reason I bring it up is because I'm also into snowmobiling and my 2001 Arctic cat Zr 500 2-stroke with power valves makes 99.5 Horsepower. Also, I have a buddy who just bought a 2011 skidoo mx-z 600 e-tec 2-stroke that makes 122 HP and he claims he gets 19 mpgs. Perhaps they're just too finicky, but the power to displacement ratio is ridiculous. Just curious is all, the 400 2-stroke single in my 400L isn't the best, but the newer ones seem pretty good.

 

Who wants to ride a smelly weed eater? Not me! Plus, they are outlawed up here. You cant compare sleds to atv's, they are a different game.

 

I heard it was because the EPA made some laws about emissions and the 2-stroke ATVs weren't meeting the requirement. It was easier to quit making them than to make them not make pollution.

 

Yep, epa mandate.

Still have one, someday I'll get around to rebuilding it.

You won't get the low end torque out of a two stroke like you would a four, but you can sure run circles around then when you get in the upper rpms.

 

Other advantages are 4strokes are quieter, no need to worry about injection oil, just gas up and go.

I know snowmobiles, PWC and Outboard can have quiet, less pollution with good gas mileage high tech 2 stroke motors like you mentioned with the e-tec from BRP but ATVs seem to be left out of the high tech and powerful motors of their Sled and PWC counter parts.

ATVs do not even get the latest 4 stroke stuff like the Polaris 750 twin Liberty that makes 85hp (145hp with a turbo) and Yamaha,s twin 600cc that makes 65hp, all 4 strokes twins.

My 2 stroke 800 e-tech makes 165hp and gets 18 mpg with great emissions numbers.

 

Fair enough. Seems to me that it's the manufacturer's loss not port these engines and other enhancements over, but I'm sure it wouldn't be as easy as it seems. I still can't believe Arctic Cat didn't build the Wildcat around the twin cylinder Suzuki 1100 Turbo (177hp) that they use in some sleds, but perhaps it would have driven the cost up to an unreasonable number.


Ha ha, true. I think my sled engages at something like 4500-4600 rpm, where as the sportsman 500 ho engages at around 2000 rpm. As you said though, they make a lot of their power at an rpm most 4 strokes can't reach.

 

Basic Mechanics:

4 stroke means 1 piston does 4 things in 1 engine revolution. (intake fuel, compress fuel, explode fuel, & exhaust fuel). Each piston does this.

2 stroke means 1 piston does 2 things per rev. (intake & compression are combined as are explode & exhaust). An excess of fuel comes in on the intake stroke as a cooling effect.

So as an example, a 50cc 2 stroke performs equivalent to a 100cc 4 stroke
but at the same burns twice the fuel & thus more emissions. So here comes the EPA & others.

Basically a 4 stroke is more acceptable it the AVERAGE rider, but performance is less. It is apparently more politically acceptable to the governing bodys & less warranty for the engine builders.

 

you need a bigger 4 stroke if you're missing something... I'd take a 4-stroke rotax any day over a 2-stroke. who wants to worry about fouling plugs and overheating 100 miles from camp? not this guy!

 

... here we go again with the sled vs atv comparision
here- just read this post for more annoying sled vs atv discussion

 

My 165hp 800R e-tech has plenty of low end, believe you me and starts moving at just above idle , plus if it was in a ATV it would be mated to a tranny with a "low range" anyways for even more bottom end grunt if needed.

BPR will not put a 800R two stroke in their ATV because ATVs have 5 psi balloon tires and spends their riding days on rough slow bush trails with rocks, washouts and stumps.
Unlike Sleds and PWC which can be open up on flat smooth lakes in safety or groomed smooth trails.

A ATV gets skittish at low speeds of 55-60 mph with off road balloon tires even on smooth dirt roads.
A sled at 100mph handles like a train on rails on the other hand.

Can-AM,Polaris ,Yamaha and Arctic Cat do not want to get sued by putting 150hp+ sled CVT motors in ATVs when people start flying off the trail into the top off the trees. LOL
The 3wheeler law suits scared them enough back in the 1980s.