Seeking snowmobile engine advice - Snowmobile Forum: Your #1 Snowmobile Forum

turbofiat124 · 12-10-2012, 08:32 PM

Hello! My name is James Seabolt and I live in the valley of Eastern Tennessee where we get little snow. So why am I here?

I own a 1981 Trabant 601 with a 600cc 2 stroke, 2 cycle air cooled engine that makes 28 HP and I am wanting to transplant a simliar sized/type engine that makes more power.

Here is my car:

Trabant Photos by turbofiat | Photobucket

This engine is VERY inefficent engine. Based on an old DKW (Audi) design built up until 1991 when the car went out of production after the reunification of Germany.

I was thinking about having my spare engine beefed up at a motorcycle shop but I was told about the only thing you can do to these engines to get more power is to shave a 1mm off the heads (2mm if you dare to risk slamming the piston into the sparkplug at high RPMs) which might give me an extra 5HP. So if I am going to transplant anything I want it to be worth my while.

I considered a jetski engine since they are more common in this part of the country but don't think that would be a good engine to use since they are water cooled designed.

I know nothing about snowmobiles since nobody around here owns one except up in the mountains at ski resorts around Boone NC.

I need an engine that meets the following criteria:

1) air cooled
2) carburated
3) 2 cycle
3) physcially about the same size that will fit my car (2 cylinder).
3) Makes at least 50 HP

It's my understanding some of the more modern two stroke 600cc engines can produce around 70HP.

I've seen Rotax engines that look quite similiar to my Trabant's engine that might work. But have no idea what makes or models or years of snowmobiles even use this type of engine.

Can someone point me in the right direction as to what to look for? Anybody know of any snowmobile breakers that sell used COMPLETE snowmobile engines? Carbs and all?

All the used engines I've seen on Ebay are basically shortblocks.

Thanks!

**smallengineguy** · 12-10-2012, 08:37 PM

Unfortunately the largest air cooled (fan) engine is a 550 cc, but they are very close on HP to what you want. These use a drive/driven clutch to transfer power to the track. How will you modify the tranny to fit?

Old Man · 12-10-2012, 09:05 PM

You're looking for something like this. You would have to jet the carbs to operate in the air temp range and elevation you would normally operate the vehicle at. You would need to use the exhaust system that was designed for the motor to ensure the proper exhaust back pressure. Also, as SEG mentioned, how would you hook up the tranny to the motor?

570cc fan-cooled 2-stroke twin. Rated at 62-63 hp, it's found in the Arctic Cat F570, T570 touring and Bearcat utility machines.

joshkidner · 12-10-2012, 09:35 PM

good question about the tranny. why dont you want to go with a liquid cooled engine? it would be quite easy to modify in a radiator compared to a transmission xD what are your plans for the tranny?

turbofiat124 · 12-10-2012, 10:13 PM

[

Quote:

Originally Posted by Old Man

You're looking for something like this. You would have to jet the carbs to operate in the air temp range and elevation you would normally operate the vehicle at. You would need to use the exhaust system that was designed for the motor to ensure the proper exhaust back pressure. Also, as SEG mentioned, how would you hook up the tranny to the motor?

570cc fan-cooled 2-stroke twin. Rated at 62-63 hp, it's found in the Arctic Cat F570, T570 touring and Bearcat utility machines.

Well I was hoping I could link the engine up to the transmission like any other engine swap.

Mount the Trabant flywheel to the snowmobile crankshaft. Build an adapter plate to go between the engine block and bell housing.

I have not dismantled a Trabant engine but based on photos, the flywheel simply slides onto the crankshaft then is held in place by a single nut. Looks like a Carter key or keystock keeps it from spinning.

The tapered end is where the crankshaft pulley goes.

trabitechnik.com - Alles über den Trabant

Trabant 601 > Spare parts > Engine: Crankshaft, complete overhauled, hycomat

The stumbling block will be if the hole in the flywheel is larger than the diameter of the snowmobile crankshaft. if the flywheel hole is smaller, then it can be simply enlarged.

The 570 engine looks like what I am after. 61hp. What holds the clutch/drive system to the end of the crankshaft? All I see is an unthreaded shaft. Unless the inside of the shaft is threaded and is not visable.

This is the drive end of the engine, correct?

I suppose a bellhousing adapter might be easier than I thought. Just use the four bolts around the crankshaft and the two threaded holes on cylidner head.

turbofiat124 · 12-10-2012, 10:14 PM

Quote:

Originally Posted by joshkidner

good question about the tranny. why dont you want to go with a liquid cooled engine? it would be quite easy to modify in a radiator compared to a transmission xD what are your plans for the tranny?

I just want to stick with air cooled for simplicity. Yeah I know water cooled engines last longer and all.

Old Man · 12-10-2012, 10:36 PM

Yes, that is the PTO side of the engine. The shaft on the snowmobile engine is tapered and threaded on the inside. No keys or key ways.

**RJ Gleason** · 12-11-2012, 12:14 AM

The 570 uses a 30mm tapered stub so it should be fairly easy to have an adapter plate made to mount the flywheel.

After looking at the links you provided, does that engine have a shroud or is it free air.
If it is free air, you could find an older Polaris Fuji motor in the 500/600cc range that would provide between 60 to 65 hp.

turbofiat124 · 12-11-2012, 05:49 AM

Quote:

Originally Posted by RJ Gleason

The 570 uses a 30mm tapered stub so it should be fairly easy to have an adapter plate made to mount the flywheel.

After looking at the links you provided, does that engine have a shroud or is it free air.
If it is free air, you could find an older Polaris Fuji motor in the 500/600cc range that would provide between 60 to 65 hp.

It has a fan driven off the crankshaft pulley and the heads are shrouded. I saw a
Rotax engine on the Ebay that was almost identical to it if i could locate the
link. I will post it.

**kccats** · 12-11-2012, 06:15 AM

The taper would be simple to addapt to, but is there some type of clutch? It might be ALOT better to addapt the drive clutch to your input shaft of the tranny?
Also you will need room for the exh pipe! The pipe is where the extra hp is made!

turbofiat124 · 12-14-2012, 06:56 AM

One more question.

Explain the electrical system on this Arctic Cat 570 engine. I don't see any external alternator or generator on this engine. But as mentioned before everybody on Ebay is basically selling stripped down shortblocks so that maybe another missing item I'm not seeing.

Is the ignition system self contained like a lawnmower? Where it uses a magnet passing across a coil to fire the plugs?

Since these snowmobiles has headlights, something has to power them. So how does that work?

Typically on small engine the charging system is built into the flywheel. Some small engines have no charging system, like push mowers. Just a coil that passes across a magnet stores power to fire the spark plug.

My Trabant uses a 220 watt 6V negative ground system. So I'm wondering how I could get around this issue.

Any idea how many watts the electrical system on this Arctic Cat 570 produces?

One idea would be to see if I could reverse the voltage instead of dropping it using a ballast resistor. I added a 6V to 12V converter on my car to power my radio but I don't know if it's possible reverse the wires and input 12 volts and have an output of 6 volts using this same device.

Of course the other idea would be to use the engines self powered ignition system to fire the plugs but mount a 6V generator to the engine block and use a longer V-belt. if there is a place to mount it.

turbofiat124 · 12-14-2012, 06:59 AM

Quote:

Originally Posted by kccats

The taper would be simple to addapt to, but is there some type of clutch? It might be ALOT better to addapt the drive clutch to your input shaft of the tranny?
Also you will need room for the exh pipe! The pipe is where the extra hp is made!

Yeah, I would need the expansion pipe. The Trabant's expansion pipe also serves as the heat exchanger.

Here is a radically altered Trabant with two massive expansion pipes!

Old Man · 12-14-2012, 07:22 AM

The ignition system is a magneto type controlled by a capacitor discharge ignition system. The magneto contains primary ignition coils (which provides current to operate the external high tension ignition coils) and a lighting coil which provides current to operate the headlight,taillight, handle bar warmers etc. The lighting coil output on the 570 is 12 volt - 210 watt.

turbofiat124 · 12-14-2012, 07:36 AM

Quote:

Originally Posted by Old Man

The ignition system is a magneto type controlled by a capacitor discharge ignition system. The magneto contains primary ignition coils (which provides current to operate the external high tension ignition coils) and a lighting coil which provides current to operate the headlight,taillight, handle bar warmers etc. The lighting coil output on the 570 is 12 volt - 210 watt.

Sounds great! Thanks.

**RJ Gleason** · 12-14-2012, 08:44 AM

That is VAC that requires a regulator to keep it at 12v and you also need a rectifier to convert to VDC.

turbofiat124 · 12-14-2012, 10:29 AM

Quote:

Originally Posted by RJ Gleason

That is VAC that requires a regulator to keep it at 12v and you also need a rectifier to convert to VDC.

So the ignition system will operate on it's own, just the lighting system needs the regulator/rectifier?

I don't know if a 6 volt regulator/recitifer could handle an input of 12 volts. Perhaps run it through a ballast resistor to drop it down to 9 volts then to the regulator, perhaps?

**RJ Gleason** · 12-14-2012, 03:52 PM

The ignition is completely separate from the lights.
Stepping it down should not be a difficult task.