Recently a buddy of mine have been debating if 4 strokes will dominate the market soon. I am of the opinion that they will. And here is why.

I am also an avid fisherman and in the last 2-3 years 4 stroke motors are about the only thing being purchased. I was really surprised at there perfromance compared to earlier models. It seems they basically offer the same performance (not quit) but close. With all the talk about the environment recently and the few 4 stroke models that we are seeing pop up in the sled industry it seems to me that just like the outboard industry we will all be riding 4 strokes in the near future. In outboard motors the dealers were telling me not to buy a 2 stroke cause they were being phased out.

I think at the current time they can't perform like a 2 stroke but I think in time they will. If it means better gas milaege and more environmtally freindly and close to the same performance and longer engine life I would be willing to make the switch.

What does everyone think?

i dont know about 4 strokes completly taking over. for the fact is the wieght difference. But then again with todays technology who knows. i no for now, i'll be staying with the 2 strockers. So far the rx 1 doesnt even impress me for the money u have to pay for them.

Dominate the market - no . Not anytime soon anyways. I think there is a place for them in the market even now, but a very limited one.

I suppose with advancements in technolgy, the four stroke will eventually become a consideration for some - just not in the immediate future.

I grew up riding motocross so I am a die hard two stroke fan. People that opted for the four stoke bikes were usually looking for a different type of ride - like enduro riding. That said, the four stroke has come along way.

Until I actually hear people talking about how good four stroke snowmobiles (rather than reading about it) I will stick to the high reving, oil burning stinkin two strokes. :p

This one could go on forever, again...wait 'til MachZZZZ1 gets in here. LOL :p I don't think the 4-strokes will "take over". Technology with the 2-strokes is producing motors that burn just as clean as the 4-strokers. It's just a matter of how long it will take for that technology to be readily available for sleds. Doesn't Doo already have this on some sleds? I think the weight issue is the biggest hurdle to be cleared for the 4-strokes. Thier performance probably isn't too far away, that can be taken care of. Personally, I don't care what I ride, as long as I don't have to give up performance. It was kind of neat being around some RX-1's on the trails a couple weeks ago, but I'm not ready to jump on one yet.

Sorry to say, if I had more time to sled I would look into an RX1. ???

Fourstroke is a possibility but its going to take alot of work before your going to get me on one. The RX1 is headed in one direction it covers more of the tripple style lake and high performance trail sleds. The cat and skidoo 4 strokes are great for people that are slow trail cruisers can't go wrong with the kinda mileage they get. There is still a gap missing. The ditch riders like me that need a lightweight four stroke. I think the only way there going to fill that area is with a smaller 4stroke with a lightweight 600 or so in a lightweight frame with a turbo. I think will see skidoos direct injection technology out first though.

If they do take over, ill be finding a new hobby :(

I see some of you mentioned the doo Direct injection technology. If I remeber right I do not believe this will ever work. For years the outboard industry tried the high pressure direct injection and it failed miserably. All manufacturers were never able to get it right and nothing but blown engines resulted. I would never ever buy a sled with this on it. What makes Ski-doo's investment even worse is that they purchased OMC and i believe are using the technology behind OMC's direct injection which was the worst one on the market. In fact in was a major contributor to them going bank rupt. I don't think the snowmobile industry will ever see a reliable direct injection. Just like the outboard industry they'll scap it put there investment in the 4 stroke.

Sorry guys I see your some of your points but I still see 4 strokes dominating in 5 years.

YOU CAN HAVE MY TWO STROKE WHEN YOU PRY IT FROM MY DEAD LIFELESS HANDS :devil: :hallo1:

Can somebody explain the shortcomings of the Direct Injection idea? From the pics I've seen of Ski Doo's direct injection engines, it looks like a regular 2 stroke motor that happens to have an injector firing fuel directly into the combustion chamber. I must be missing something here, because other than making an injector nozzle that can withstand the combustion temperatures & pressures, I don't really see the big deal.

Originally posted by rbig18@Jan 29 2003, 01:42 PM
I see some of you mentioned the doo Direct injection technology. If I remeber right I do not believe this will ever work. For years the outboard industry tried the high pressure direct injection and it failed miserably. All manufacturers were never able to get it right and nothing but blown engines resulted. I would never ever buy a sled with this on it.
I can tell you that DI technology works from personal experience. I've got a 1100 jetski with DI and a 900 without. The heavier DI machine uses 40% less gas than the 900 with the exact same hull design. Even with the DI's throttle pegged all of the time :p My wife babies the 900, just cruising around, and the mileage sucks.

I also had a chance to compare the DI 1100 to the non DI 1100. It feels like a different machine.

I would love to see a DI sled, as long as its green.... ;)

I hope not!!

Rick.

I'm not an expert, but from what I think I know, Ski-Doo has SDI (semi-direct injection) which does not inject fuel into the combustion chamber. It is injected into the cases after the after the exhaust port is closed off. This is very efficient, but the system requires WAAAAY less fuel pressure than a true DI system. (I think the Kawi jet ski also uses semi-direct injection)
I also understand that true DI can not be made to work above 6500-7000 rpm because fuel pressure required is impractical. Note the outboards - they max out at around 6000 rpm.
As for 4 strokes - check out this months cycle world mag. Honda V5 GP bike -1000 cc, 230 to 250 HP,
5 cylinders, 4 stroke. (and the entire bike is expected to weigh <350 lbs) Can you imagine that engine in a sled!!!!!!!

Jim, the current problem with DFI on a snowmobile two stroke (if you believe what has currently been discussed publicly) is the rpms a sled motor runs at.

DFI works great for watercraft (Sea-Doo, Wave Runner, etc) because these two strokes turn much lower rpms than a sled motor. Sled motors currently run somewhere around 77-8000 rpms for peak power. The number of times a DFI has to charge and fire per minute at this rpm leads to problems. DFI is much happier at 6500 rpms and below.

Think about it, most sleds just start to engage the clutch at 37-4000 rpm. At that rpm on a waverunner you are running 30+ mph.

Direct injection cleans up two stroke emissions because the fuel is injected at a predetermined amount into the cylinder after all exhaust ports have been closed. Thereby preventing any fresh, unburned fuel from exiting the exhaust pipe. The distance from the top of the exhaust ports to the point of ignition is unbelievably small when a motor is running at 3000 rpm, not to mention WFO.

Now, realize that DFI involves taking a charged fuel system, say 20 psi in the line, and increasing that to 3000 psi or more at the point of injection to provide complete atomization. This insures that the fuel is spread across the entire combustion chamber and also permits complete combustion of the fuel/air mixture.

Now image the time it takes for a piston to complete a power stroke at WFO and you can see the problem.

Insurmoutable, I doubt it. Hell, they could build 1000 -1100 cc motors right now that would pull the low rpms and do DFI.

Oh, and by the way, Ski-Doo&#39;s SDI injects in to the transfer port, not directly into the cylinder, thus, SDI, not DFI.

Yeah, Yeah, I know, but with little snow until recently, I actually read and tried to understand some of what has been printed on this issue. :)

Renegade - the reason super high pressure is needed on direct injection engines is not ONLY to overcome the combustion pressures when injecting the fuel into the cylinder. The pressure must be high enough to supply ENOUGH fuel per stroke. If you can&#39;t get enough fuel into the engine, you won&#39;t make HP (no fire=no heat).
The only way for small displacement engines to make HP is with high rpm (HP=torqueXrpm)/ constant. A 150 HP outboard has 2000cc. A 150 HP sled has 800 cc. Outboard runs at 6000 rpm sled runs 9000 rpm.
This is why I don&#39;t think direct injection is going to happen in sled engines in the 1000 cc range (unless the sled owner is going to settle for 50 - 70 HP in his 1000 cc machine redlining at 5000-6000 rpm.

If they can control the weight problem maybe but other than that sure as hell hope not

I&#39;ll stick to 2 stroke on my sleds but atv&#39;s my 4 stroke 400ex is just perfect for me.

Konkinj--When you say snowmobile engines run a 9000 rpm I believe you are referring mostly to high-strung triples and some warped-out twins.

What I was refering to was a 1000-1100 twin 2 cycle. If I remember correctly, the Cat 900 likes to spin around 7300-7500, so if you drop that even more because of a bigger cc motor which is going to be happy spinning lower rpms yet, they should be able to do it.

Now, that obviously means more weight in the motor and as the consumer is telling the manufacturers, that doesn&#39;t cut it.

Will it happen? Who knows. An educated guess would be to look at the outboard market and see if any of the DFI 2 cycles spin sled rpms. If not, I would venture to say SDI is what you will see until it no longer meets EPA emission standards.

So, I am with you on this one.