THOUGHTS... FACTORY 4 STROKE IN AN AXYS CHASSIS??
- Thread starter Motorbreath_
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sportsterdanne
Well-known member
In one of the Nypro build threads the 600 Pro engine was about 30 lbs lighter than the Nytro engine.
the Phazer engine is pretty powerfull at 80 Hp and only 500cc make it 1000cc and 160HP NA and it would still be in the 600 class if the same rules as motocross is used.
To get a 800 class 4 stroke it should be closer to 1500cc and that is alot for a twin, then you probably would have to have 3 cyl and the weight it adds.
the Phazer engine is pretty powerfull at 80 Hp and only 500cc make it 1000cc and 160HP NA and it would still be in the 600 class if the same rules as motocross is used.
To get a 800 class 4 stroke it should be closer to 1500cc and that is alot for a twin, then you probably would have to have 3 cyl and the weight it adds.
Seems like the constant high rpm use the sled gets is the bane of the snowbike community. Most light 4 strokes do not like the amount of sustained high rpm use snow riding seems to require. Valve adjustments and oil changes every couple of rides? Expensive top end rebuilds every couple of seasons?
The big bike based motors seem to do well here but I agree with the weight comments. Until they get it way down, I think it is a hard sell and a small market.
Like most others though, I will take the holy grail version... Under 400 lbs, 160-180 hp that runs 5000 miles between rebuilds. Needs to be priced with the 2 strokes not 2 grand extra like the Cat 9000, or turbo Viper.
I would like the 2 stroke snap though and have never found it in a 4 stroke. Maybe you can clutch for it but one of the best features of the 800 Axys is the lift which is aided in large part by the 2 strokes instant response.
The big bike based motors seem to do well here but I agree with the weight comments. Until they get it way down, I think it is a hard sell and a small market.
Like most others though, I will take the holy grail version... Under 400 lbs, 160-180 hp that runs 5000 miles between rebuilds. Needs to be priced with the 2 strokes not 2 grand extra like the Cat 9000, or turbo Viper.
I would like the 2 stroke snap though and have never found it in a 4 stroke. Maybe you can clutch for it but one of the best features of the 800 Axys is the lift which is aided in large part by the 2 strokes instant response.
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snowmobiler
Well-known member
rzr prostar turbo twin is like 25000?.im out.LOL
RZR 1000 motor already has a pto crank snout for a Polaris clutch.
Great thread....we need more of these. I ride a normally asperated Nytro MTX that is stripped down to 565 RTR, so call it 460 lbs dry???. I've got the motor up to maybe 145-150Hp and even though I ride my lightweight XM mostly, I still love the Nytro because it absolutely rips off the bottom. The engine has more grunt than any 2S and when you need to modulate power, it is a way more forgiving sled.
That said, I totally agree these powerplants need to go on a diet but the gap is not as big as you think. Think about that big insulated tuned pipe on a 2S. I'm guessing it's around 20 lbs on my XM and it is way out in front of the engine, so not exactly mass centralized. You gotta add this weight back in because the engine is useless without it.
The Nytro engine could loose 20 lbs by ditching the internal starter/one way clutch abortion on these engines as well as the "splined" crank that has a huge chunk of iron that adapts from the crank to the tapered clutch mount. It's very heavy and the Suzuki 1100 doesn't have it, so it's definitely doable.
I think the next round of 4S engines should get within 20 lbs of "net weght" difference to a 2S and when that happens.....all bets off.
Great thread guys!!
OTM
That said, I totally agree these powerplants need to go on a diet but the gap is not as big as you think. Think about that big insulated tuned pipe on a 2S. I'm guessing it's around 20 lbs on my XM and it is way out in front of the engine, so not exactly mass centralized. You gotta add this weight back in because the engine is useless without it.
The Nytro engine could loose 20 lbs by ditching the internal starter/one way clutch abortion on these engines as well as the "splined" crank that has a huge chunk of iron that adapts from the crank to the tapered clutch mount. It's very heavy and the Suzuki 1100 doesn't have it, so it's definitely doable.
I think the next round of 4S engines should get within 20 lbs of "net weght" difference to a 2S and when that happens.....all bets off.
Great thread guys!!
OTM
You're correct about shaving weight of power plants. There's many thoughts out on weight reduction solutions. I wish someone would post shipping weights of a 800CFI and RZR 1000 motors. I've heard going from 6 pounds to 12 pounds of boost on RZR 1000 makes 200hp
We've been throwing around lightened RX-1's in the cascades since 03. We have 9 still running. I am ready for a new sled, have no interest in going back to a 2-stroke, and have yet to see a new naturally aspirated 4-stroke that can touch our sleds in the mountains. I decided to yank my ole trusty sled's engine this summer; over 12k miles on it but still running strong. Plan is to re-ring it and stuff it in a 2016 pro155 I picked up from a rental fleet for $4k last spring. So far the install is amazingly simple. Even for A low-tech guy like me. A little grinding, some simple engine mounts from 3/8 plate. All that's left is the exhaust which I'm routing forward. Engine looks more at home in the Pro than in the one ton. I'm currently at 443lbs, no gas, no fluids, no exhaust. Oil and coolant will add about 17lbs. Hoping to come in at under 470, no gas. Big wt. savings over the lightenned one tons which we love. Can't wait to see how it does on the snow.
I'm excited to see this build perform. FWIW, that is not an Axys, but an earlier pro-ride.
I'm surprised snowmobile motors haven't followed the path of automobile motors. Most cars have dropped a couple cylinders and added a turbo or two.
A comparatively de-tuned motor with a turbo putting out the same hp as a NA 800CC motor would be a great option. Most of us ride at altitude so there wouldn't be as much horsepower loss. You could even take BMW's approach and use 1 turbo for lower on the power band and another for the higher revs, which may be a bit low on room but that's not my job.
I feel like the reason this trend became popular on the automotive side was because of a push for cars the become more efficient. But it also could be because engineers had a bit of a breakthrough in turbo technology. Who knows. I'm not too hopeful snowmobile companies will be in a rush to follow suit but I would love to see it.
A comparatively de-tuned motor with a turbo putting out the same hp as a NA 800CC motor would be a great option. Most of us ride at altitude so there wouldn't be as much horsepower loss. You could even take BMW's approach and use 1 turbo for lower on the power band and another for the higher revs, which may be a bit low on room but that's not my job.
I feel like the reason this trend became popular on the automotive side was because of a push for cars the become more efficient. But it also could be because engineers had a bit of a breakthrough in turbo technology. Who knows. I'm not too hopeful snowmobile companies will be in a rush to follow suit but I would love to see it.
There is a reason why it fits as well as it does in that chassis.
Polaris had a turbo-twingle that had zero sex appeal and an exhaust that was totally unremarkable. I think some canadian was able to hack the ECU and get over 170hp out of it - not bad for 750cc. That's gone and never coming back.
I bet Polaris has had many discussions about 4S engines in sleds. But to build a dedicated dry sump snow 4S engine is a retarded amount of money for such a small product group. I bet they've gone through several iterations and how many have we seen in production?
What is the turbo 1000 RZR motor capable of putting out? I too love the 4 stroke but went to the AXYS for the lighter weight.
Just over 200
We have the 145-150hp Yamaha RX-1 998cc 4-stroke motor in the Polaris Pro chassis. We have done three of them and are about to do a fourth. The mod is simple and it gives new life to the many Pro chassis's out there with blown motors. Wet with a 163in track it weighs 561.7 lbs, the exact same as a weight as a 2020 Skidoo Summit SP 850 165 (561.9 lbs), and the pro holds 2 more gallons of gas than the doo. It climbs and it handles. An Apex motor produces 162hp and is few pounds lighter. There's absolutely no reason a manufacturer can't produce a competitive 4-stroke mountain sled.
I could see 4s taking over the lower range. Doo has made commitments to both sides with the ACE and new 600s. The 600R is pretty impressive; the new-this-year base 600 not so much, making similar power per displacement to the 90's Indy 500 EFI. The 550 fan is very dated (though not a bad for what it is), and the 600 hasn't seen any changes in a while, so I could see them on the chopping block. If they do come out with some four-strokes, I just hope Polaris doesn't kill off everything but the 850 or let the 600 and 800 plod along with no improvements.
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