Any Interest in sled engines?

[KoogarKiller]

Gotcha... I have not played with the different spring positions at all.

I would say that the low gearing is half of it and I am trying to more or less tune the secondary to help, I don't want to swap gears till I get to test it in the sand with the 26" sand tires ... The primary seems to be right on (It was set up for the Sled) and it runs around 6800-7000 before going full shift then reving out (hard to tell what the tach says at that point cause I'm going so fast down the street)... I would say it's getting up to about 7800+ tho.

I will play with the settings on the secondary some and see if that helps... Was checking out those Wide Ratio Kits from TEAM and wondering if that might be a happy medium while keeping the 10:1 gears?

I can prolly take a tach video if your interested?

[KoogarKiller]

thanks for posting the site with the Phazer powered mini buggies too! I enjoyed reading about those builds.....

[sho305]

Long ago I had an SRV its a fan 540cc yamaha, had a PSI pipe on it and the high altitude clutch kit. It would be killer in a cart the engagement was very smooth but powerful, it was very snappy on the trail.

Far as tuning you want the tach to sit at your power peak rpm all the time once moving (when WOT), this is very important if you want full power. Normally it climbs from engagement rpm to shift rpm gradually until you have enough speed where you can have full power without spinning. If you over rev you need more gear to go that fast the power will fall right off. If still shifting the weights and spring in the primary mostly determine shift rpm. The secondary spring preload (twist) determines rpm at part throttle, more preload means more rpm at half throttle and stays up when you let off throttle at speed so you get some backshifting. A ton of preload in theory would keep it at your ~7K shift rpm all the time no matter what throttle you were at.

Some sleds now use roller secondaries where they can vary the helix angle, and make them shift harder to lower rpm at high speeds for example....by changing the angle at the high speed ratios. The helix makes the secondary react to engine torque, when it senses torque it shifts down to get you back to shift rpm (top rpm). Unless you have preload really high, then it will keep it near shift rpm all the time.

There are comet manuals on the net that tell you how to tune clutches for sleds. Some is trial and error such as how it engages, because some combos will hit hard and some soft. I think my srv ran a purple or pink spring for the high altitude, whatever is listed from yamaha. The early phazer and the srv are very similar motors, yeah all those 80s yamaha sleds were bullet proof except a couple of them. Even the 340 would run 60mph in a sled.

[KoogarKiller]

What exactly does a Hi Alt kit do? I remember you talking about this before...

The take off on my set is perfect.. after switching to a Pink Spring (softest one I could find) ... It engages @ 3000rpm and hits hard enough to pop a couple inches of wheely when the suspension shifts all the weight to the back. It originally had a silver spring and engaged @ 4000rpm really hard... I figured it would beat up my rear end too fast.

So if I put my secondary spring on the least preloaded position if will do cruising speeds at lower Rpms? Is it a big defference?

I am running a Team Ind roller seconary .... It has a red spring in it

[sho305]

High alt just lets it rev higher at low speeds to compensate for lower HP in thin air. It was always an easy performance kit, and if you put studs in the track you usually could make good use of it anyway. It usually still engaged normally, not hard, usually on the trail it would respond faster and get rpm quicker when you gassed it.

Yes, less preload on the secondary will let rpm drop at part throttle. Only thing you have to watch is the torque can eventually suck the belt down into the secondary if it is too weak, though that might depend on the spring....the static pressure of the spring (not the preload you twist into it because you will hardly have any then). The secondary is also responsible for belt tension so it can't slip into or on the sheaves, but too much pressure wastes energy and causes wear. If it does slip it will bog down, slipping down into the secondary is like slipping into high gear.

Depends on the spring in there how much difference you will see. With a stock GC secondary there is a huge difference it will shift out to quite low rpm stock and some carts you can go a little lower yet. It does make it slower to respond while you wait for it to shift back down when you nail the gas. If you wind a stock secondary up really hard it stays right near shift rpm all the time, like 3K or more for a stock cart that shifts around 3600. The cart will not go until you get around 3K it runs pretty strange that way, tried it with mine for kicks. Of course with a sled motor you must have a minimum rpm or it makes no power and limits cooling. Maybe that is around 3K depending on the engine, 3K is pretty slow for a sled engine that runs full power at 7K. It depends on the engine, for example the 540 srv was tuned for more torque for crosscountry racing, the 485 phazer was more sport tuned. So the 540 has a nice midrange and the 485 is more of a topend engine it needs the rpm to roll. IIRC the phaser was indeed faster than the srv, but the srv had a steel body to take lots of punishment and it was not near as light. But in simple terms you engage lower to limit power on takeoff, because spinning does not win races. With a studded track you can raise it up because you have a lot more traction, at least on hardpack you did.

[Catch22]

I have a 1979 EX 440 snowmobile motor is it possible to make it run Backwards because I plan to put it in a g1 gas golf cart with no reverse in the rear end........ Can I use the stock G 1 exhaust or should I run an expansion chamber

[sho305]

I'm not sure on the backwards part, when using a 250 single yami sled engine you can adapt the G1 ignition plate to it....for a twin not sure. Though they do often fire both cylinders at same time there is not twin ignitions just 180 degree firing. You would want to use the sled pipe because the porting is way different, you will lose a lot of power if you don't.

Other sleds do run backwards some skidoos did it nicely it would change direction instantly.

[opsled]

It will run backwards. Timing will be late in reverse but is adjustable to get closer to TDC if needed. That will limit power in forward but it probably won't be noticable on a cart. The stock G1 pipe will skunk the 440. Possibly to a point wher it won't run well at all. Also not sure if the G1 starter will even spin it. Those Ex engines have the oil pump drive gear attatched to the back of the OEM clutch so replacing it with another will eliminate the oil injection. Comet made a 102 replacement for it but there were no provisions for a starter belt pulley to be attached.

opsled

[WJ ezgo]

Originally Posted by opsled

Just wondering if there is much interest in sled engine swaps. It seems as though there isn't but I'm not sure.

The reason I ask is that is a large part of what I do for a living (sleds and engines) and could easily put together complete running engine packages of many different sizes, makes and configurations if there was a market for them. Fan or liquid cooled in HP ranges from 25ish to over 100.

What I consider to be a complete package would be an E-start engine with all the fuel/oil, exhaust, mounting and electrical components to run the engine and the CVT (clutch) system it was run with. Usually the electricals would be complete with harness and guages. Liquid cooled would require a radiator. Adapting (fabricating) the components to fit would be up to you.

Pricing would range from around $400 up depending on the engine. I've done many in the past but I'm not sure if it's worth my time to do them in today's market.

Here are a few examples of some of my past engine packages.

Any Thoughts??

Phil

VERY NICE!! There IS a market for two strokes. 4-strokes are too expensive and their power to weight ratio is horrible compared to 2 strokes. But of course you already knew that! Where are you located?

[ChvyCruzen]

I am looking for a 340 - 440 sled motor with e-start. I'd like a complete package so it would be easiest for me to install. That Yamaha 340 e-start looks like a good package, got anything like that I can buy?