30hp out of an industrial engine would be heavy. Look at an atv engine.

 

30hp out of an industrial engine would be heavy. Look at an atv engine.

Perhaps, but then again you have not read B550's write up on the motor and comments on the weight of the little single he is using. It is modified to get the HP.

Dan

EDIT - Following are some of the comments concerning the engine:

The engine scheduled for now is a GX460 clone with many modifications. Copy of a Honda GX390 but 460cc, more compression, more cam, more solid parts ...

I was looking at the specs of the Honda GX390 - wow, only 69 pounds dry which is very good for a 4-stroke single.

And has 69lbs this includes metal fuel tank, exhaust, carburetor, ignition and cooling system. A single GX390 engine block should weigh about 55lbs. For other type of engine, weight specifications only considers the engine block.

But, nothing wrong with an ATV motor if you could find one that was a 4-stroke single and only weighed 55 pounds like the motor B550 selected. A 277 weights 40 pounds so perhaps we could gain the 15 pounds somewhere else. Considering the cost of a complete 277 rebuild it might be good to look at options. These "industrial" motors go for a great price.

 

I know you can get there with a modified Chonda, but why hurt reliability and make it noisier? Might as well just stick with the 2stroke then.

 

I know you can get there with a modified Chonda, but why hurt reliability and make it noisier? Might as well just stick with the 2stroke then.

You make a good point. I guess that B550 would need to chime in to let us know how noisy his motor is compared to a 277. It is hard to tell from a video. As far as reliability A modified industrial motor would not be as reliable as a non-modified industrial motor but perhaps it would be as reliable as a recreational motor or as a 2-stroke - another good question of yours. My 550 single ATV motor is nice but not without problems. It needs a radiator to keep it cool whereas my Honda motorcycles 500 and 650 that I previously owned did not require a radiator. In addition the Polaris ATV is a pain to work on with liquid cooling, a cobbled up external oil tank making it difficult to change the oil, and added complexity compared to my 1987 TLR200 street legal trials bike for example that just keeps running and running. I like the simplicity of B550's setup and of at least the older Honda dirt bikes.

So far, B550's is the only example of a working single cylinder lightweight single cylinder 4-stroke that we have to go on. Anyone know of any other snowmobile mods where something like this has been done - 4 stroke single?

Dan

 

This piques my interest as well Dan , I certainly appreciate the light weight of the 2 strokes but the sound and smell is really starting to wear on me . There must be an ATV motor out there that uses a centrifugal clutch that would be a likely candidate for a swap ? My Skandic wide track motor was rebuilt by a former racer who tweaked some additional power with porting and increased air flow and it makes crazy power but the sound is obnoxious and the power band is completely wrong for utility work , I wish I could find something akin to the 600 ace from the wheeled powersports world to replace it with .

 

I have read some of b550's thread, but not all. I will fix that shortly though.

He had all kinds of neat ideas in there, so fundamental, so NEEDS based, rather than WANTS. While today's marketing focuses on wants, there is an emerging market that just wants to meet needs. I still like the 350-400cc air-cooled ATV engines, but admit that cooling them is an issue on a sled.

Do you have anything picked up yet in a chassis to work on? Let's see some pics!!

 

There are 3 big problems with adapting an ATV engine to a snowmobile. The weight, the location of the transmission and the cooling system.

Small comparison here with my 2 off road gokart, one has a Suzuki 300cc ATV motor air cooled with a 5 speed transmission, the engine block with the transmission = 125lbs.
The other has a fan-cooled 420cc industrial motor with a 3 speed manual transmission in series with a small CVT, the engine and the 2 transmission drives 80lbs. Apart from the competition motorcycle engines (250 and 450) that are lightweight for their power, ATV motors are pretty much all heavy, in fact much than 2-cylinder snowmobile engines.
The ATV and reverse foward reverse gears are configured behind the engine, so that a snowmobile has a light front, the engine must be glued to the front of the tunel (just in front of the sprockets) and the CVTs must be next to and on the Above the engine. Unless you put the ATV engine up in the air for the transmission to be above the tunnel, I do not see how to get a short, light snowmobile on the front. In addition the power goes out behind the transmission in the center and not on the side!
Engines that have a liquid cooling will ideally need a radiator above the track unless you keep the big radiator with the fan in front.
Those who have an air cooling will need a very powerful electric fan, the snowmobile must provide a constant high force to advance unlike the ATV on wheels. The industrial motor has a fan and is capable of cooling without advancing.

The ideal would be to engineer an engine from A to Z to get the obtimum on a small snowmobile instead of using an engine that is not designed for that. But cost $$$$$$.

The first Small-Doo is much quieter than the Tundra R with its original exhaust. The Small-Doo X is just a little less noisy than the Tundra R, but its very minimalist exhaust system weighs less than 2lbs.

 

I have read some of b550's thread, but not all. I will fix that shortly though.

He had all kinds of neat ideas in there, so fundamental, so NEEDS based, rather than WANTS. While today's marketing focuses on wants, there is an emerging market that just wants to meet needs. I still like the 350-400cc air-cooled ATV engines, but admit that cooling them is an issue on a sled.

Do you have anything picked up yet in a chassis to work on? Let's see some pics!!

The majority of the young guys here want to have a very powerful engine and a very long track, and the older guys want a big trackr, a big 4 stroke engine and all the possible equipment. Do they really need them ...

 

Hi B550,

My original thought was to wonder if the engine you used in small doo II could be adapted to a Tundra II (no reverse) since it has about the same HP and more torque and you say it is actually a little quieter. Do you think that is possible or too major of a project? My motor is still like new but if I ever have another failure that would be something that I might consider. I'm sure it would not be an easy conversion. I don't know if a primary clutch for the 4-stroke could be found to work with the Tundra secondary. Then there is the belt distance, etc. Perhaps it is not possible or practical. You are right that many simply look for HP but there are some that want a reliable, powder capable, high performance at low speed machine.

Dan

 

Hi Dan,

The most difficult part will be to build good motor support to accommodate the GX460 engine while being in line with the Tundra pulley (after assessing if there is space)
It would be possible to recover the power block clutch of the engine of the tundra, but it would be necessary to machine the pulley and the shaft of the 460 engine . Then it would be necessary to calibrate it. Or buy a Comet Duster with a 1 "straight shaft hole.
All the electronics will have to be redone, it will be necessary to put an LED light in front, because the coil of the industrial engine produces less than 60W.
The gear must be faster, because the maximum speed of the engine will be 5000 RPM instead of 7000RPM.
The exhaust could easily be quieter than mine, with a harvier exhaust than 2lbs (the silencer of the Tundra 2 weight 12lbs)

 

Hi Dan,

The most difficult part will be to build good motor support to accommodate the GX460 engine while being in line with the Tundra pulley (after assessing if there is space)
It would be possible to recover the power block clutch of the engine of the tundra, but it would be necessary to machine the pulley and the shaft of the 460 engine . Then it would be necessary to calibrate it. Or buy a Comet Duster with a 1 "straight shaft hole.
All the electronics will have to be redone, it will be necessary to put an LED light in front, because the coil of the industrial engine produces less than 60W.
The gear must be faster, because the maximum speed of the engine will be 5000 RPM instead of 7000RPM.
The exhaust could easily be quieter than mine, with a harvier exhaust than 2lbs (the silencer of the Tundra 2 weight 12lbs)

Could a straight-to-taper adapter stub not be used here? Of course that would increase the width of the powerhead and perhaps require a RHS weight bias, but it's an option that could avoid the full engine teardown... not that a GX460 is that hard to work on, but that's still time consuming when you're fabbing so much else.

Would love to see this built!!

 

Hi Dan,

The most difficult part will be to build good motor support to accommodate the GX460 engine while being in line with the Tundra pulley (after assessing if there is space)
It would be possible to recover the power block clutch of the engine of the tundra, but it would be necessary to machine the pulley and the shaft of the 460 engine . Then it would be necessary to calibrate it. Or buy a Comet Duster with a 1 "straight shaft hole.
All the electronics will have to be redone, it will be necessary to put an LED light in front, because the coil of the industrial engine produces less than 60W.
The gear must be faster, because the maximum speed of the engine will be 5000 RPM instead of 7000RPM.
The exhaust could easily be quieter than mine, with a harvier exhaust than 2lbs (the silencer of the Tundra 2 weight 12lbs)

Hi B550,

If I understood you correctly a comet primary clutch could fit on the shaft without modification. That could be the way to go. I almost bought one once for my Tundra and knew it could be calibrated for the Tundra. So, @5000 rpm it might be a little slower but not a big problem. Of course I still have my stock gears in a box so gearing higher would not be a problem. The CVTech clutch is easy to calibrate but I don't know about the comet. However, I don't currently have a need to do this conversion - hum, maybe if I located another Tundra in this part of the world - hard to do. I think that the electrics could be kept very simple. Some thought would have to go into the motor mounting especially with the handlebars in the way.

I think it would be a very interesting conversion. Thanks for your input. Your motor is modified for more HP so that would add to the expense.

Dan

 

Could a straight-to-taper adapter stub not be used here? Of course that would increase the width of the powerhead and perhaps require a RHS weight bias, but it's an option that could avoid the full engine teardown... not that a GX460 is that hard to work on, but that's still time consuming when you're fabbing so much else.

Would love to see this built!!

For my Small-Doo X, I bought a Comet Duster with a 7/8 "threaded hole (at a good price). Enlarge the hole to 1 '', make the keyway ¼ (hard to do) Then I cut the shaft of the 460 engine and redo the tread in the center of the shaft without removing the shaft from the engine. And all seems to hold well

But it dont work if the Tundra pulley is larger than 25mm.

 

Hi B550,

If I understood you correctly a comet primary clutch could fit on the shaft without modification. That could be the way to go. I almost bought one once for my Tundra and knew it could be calibrated for the Tundra. So, @5000 rpm it might be a little slower but not a big problem. Of course I still have my stock gears in a box so gearing higher would not be a problem. The CVTech clutch is easy to calibrate but I don't know about the comet. However, I don't currently have a need to do this conversion - hum, maybe if I located another Tundra in this part of the world - hard to do. I think that the electrics could be kept very simple. Some thought would have to go into the motor mounting especially with the handlebars in the way.

I think it would be a very interesting conversion. Thanks for your input. Your motor is modified for more HP so that would add to the expense.

Dan

Hi Dan,

The comet Duster is calibrate like CVtech power plock. Yes the electric on inductrial engine is simple.

This engine was extreme durable but is was more expensive than racing gx witch a lot more hp.

http://www.brandnewengines.com/GX440-VDAA.aspx

 

One of these motors such as the 7100 rpm and 11.5 HP World Formula could possibly be a slick replacement for an Elan motor.

http://www.briggsracing.com/racing-engines

 

One of these motors such as the 7100 rpm and 11.5 HP World Formula could possibly be a slick replacement for an Elan motor.

http://www.briggsracing.com/racing-engines

yes a small block like first small-doo witch some performance improvement. But 7100RPM is the RPM limitting, the maximum horsepower is in 5500 - 6000 RPM. So the cluch must bi run at 5500.

Here is the palace off modded racing industrial engine ! http://www.nrracing.com/category-s/2139.htm
But the horsepower is over estimates (or mesured) by 10% to 25%
You can save some money if you build yourself, but you need many parts.

 

yes a small block like first small-doo witch some performance improvement. But 7100RPM is the RPM limitting, the maximum horsepower is in 5500 - 6000 RPM. So the cluch must bi run at 5500.

Here is the palace off modded racing industrial engine ! http://www.nrracing.com/category-s/2139.htm
But the horsepower is over estimates (or mesured) by 10% to 25%
You can save some money if you build yourself, but you need many parts.

That is a good link - brand new motor cheaper than many 2-stroke complete rebuilds.

 

That is a good link - brand new motor cheaper than many 2-stroke complete rebuilds.

looks like a $900 460cc to match 277 power. I think I would stick with the 277. If you go with the 460, maybe look into the new cub cadet EFi system made by Walbro. I have it on my mower. It is stupid simple (in tank fuel pump to throttle body, and an O2 sensor. All electronics on the throttle body), and is supposed to be pretty universal between 8hp and 30 hp. It might be a good match for a 460cc Chonda. Easy starting, no tweaking the carbs, save some fuel and can handle ethanol up to 15 or 20% IIRC.

 

The EFI system has piqued my curiosity but I have not found a system Walbro for sale for individuals.
I found another one that can fit motor from 35 to 800cc (with different size of trottle body)
But the EFI cost system also comes more expensive than the full engine ($ 700 usd) and the flywheel ($ 135 usd and coils ($ 95 usd) must be changed because the EFI system needs 4 amperes continuously to work.
I would still like this system because it would ensure a better mixture of gasoline air throughout the range of the engine and it would allow to induce the variable timing of the alumage (better performance at high speed without compromising the operation at low speed And ease of starting !!

But all these small electronic components will not be as reliable as that of an automobile (Chinese manufacture)
Only one of these components will be defeated, or the snowmobile battery will become too weak, and one will fall into the wood without being able to repair itself! A carburetor does not work perfectly, but there may be situations where it may not allow us to come back home (like mukuni).
If this system would be as reliable as the systems of the recent snowmobiles, I would take it (but still dependent on a battery on the 4 strokes) but I'm long to be reassured.

Geoff de Vegascart (the one who developed the 460cc block) is developing an EFI system, but it is not ready. And it is very difficult to manufacture a system for a very specialty market in small quantity at a reasonable price.

The 460 engine from 27HP to $ 900 is the same engine as the 460 at 25HP at $ 600, it only has one more aluminum flywheel, this gives no power, only a better trottle responce. And it has no way to install a coil on that at $ 900, only on that at $ 600, which is by far the best value for money, it is manufactured in greater quantity. It was my engine to start before modifications.

I am very septic about the powers announced on NRracing, higher than the theoretical calculations can give.
The powers of the manufactures of snowmobiles are also exaggerated (one does not use the powers announced on a dyno that has no factor of corection cheated) but not so much.

 

The Walbro efi comes at about a $200 premium on the mower I purchased. It could hit the market for 250 when it's ready. For independent sales, but probably about twice that.

 

looks like a $900 460cc to match 277 power. I think I would stick with the 277. If you go with the 460, maybe look into the new cub cadet EFi system made by Walbro. I have it on my mower. It is stupid simple (in tank fuel pump to throttle body, and an O2 sensor. All electronics on the throttle body), and is supposed to be pretty universal between 8hp and 30 hp. It might be a good match for a 460cc Chonda. Easy starting, no tweaking the carbs, save some fuel and can handle ethanol up to 15 or 20% IIRC.

I like the "stupid simple" part. The 277 2-stroke is a great little motor that is as lightweight as possible considering the cost so that is probably why we are not finding a whole lot of interest in this topic. However, if someone pulled off a practical conversion, got the noise level down, and chose the right 4-stroke single I think it could catch on. Perhaps there could be a niche market for a do-it-yourself kit if the price was right. An Elan could be a better candidate than a Tundra for such a motor since you would only be competing with a 12HP 2-stroke or 18HP for the Elans specially made for over 5000 feet elevation. Or, I have always liked the idea of an Elan/Tundra - Elan with Tundra LT track and slide suspension. I don't know if there are more old Tundra's or old Elans sitting in peoples garages, barns, are sheds with a worn motor but decent hull that aren't being used.

Dan