ROTAX 185 cc, 2-cycle 9HP Engine from Wajax "Pacific Pumper Mark 3" Fire-Fighting Rig

MoTo-BunnY

MoTo-BunnY

Member
#1
#1
This is a Rotax of Austria 185cc 2-stroke engine, all aluminum with steel cylinder insert, that came off of a fire fighting rig that consists of a pack-board frame and stainless tubing. It was designed to be backpack-able to remote locations and put to use fighting forest fires and they remain in use to this day.

We picked it up at a swap meet and had never seen anything like it. I've been doing some research and apparently these engine were also used on ultra light aircraft and go-karts. So, I'm wondering if anyone here has any experience with them, especially on minis? Would this be a good minibike motor? Seems like it would really haul butt, if you did. :scooter: I'm wondering if you can still get parts for them, too (as Rotax no longer makes them, Wajax bought the rights years ago and uses them exclusively on their water pumps, I guess. For such a popular engine back in the day, it doesn't seem like there is a whole lot of information on them on the Internet, for some reason.

Here are a bunch of pictures (note that the water pump is missing) The engine looks to be in pretty good shape-everything moves freely and inside the combustion chamber, it's not too carbonated. None of the fins are broken off and the muffler has minimal rust on it, I kind of don't think it was run very much? I found an engine number on the tag but no information to date these type of engines anywhere. The pack frame looks Vietnam war vintage (according to two older guys now, that know military stuff and saw it. ... lol) so best guess is late 1960s, early 1970s?

Here is the Wikipedia article on this engine:
Rotax 185 - Wikipedia, the free encyclopedia

From the Wikipedia article:
General characteristics

Type: two-stroke air-cooled engine
Bore: 2.441 in (62 mm)
Stroke: 2.4 in (61 mm)
Displacement: 185 cc (11.56 cu in) (changed this number as the Wikipedia entry is wrong. . .lol)

Components

Valvetrain: piston ports
Fuel system: Tillotson pneumatic pump carburettor
Fuel type: regular autofuel
Oil system: premixed in the fuel at 40:1
Cooling system: free air
Reduction gear: Custom made belt drive reduction units have been employed

Performance

Power output: 9 hp (7 kW) at 5000 rpm
Fuel consumption: 4 l/hr (1 US gph)
​


Also, I tracked down a parts manual .pdf but no other literature....I would appreciate it if someone had an operating and/or service manual to share?











 
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trinik7597

trinik7597

Active Member
#2
#2
rotax is a very popular motor with some friends of mine who race flat track they switched them out instead of hondas years ago for reliability and they still rebuild them so parts must be available
 
Neck

Neck

Growing up is optional
#4
#4
Not that it matters, but they got the cubic inch numbers wrong. It comes out to about 11.25 cubic inches.
 
MoTo-BunnY

MoTo-BunnY

Member
#6
#6
Rotax parts are still available, as they make plenty of engines still, however I don't know about the 185 as it was "orphaned" by Rotax years ago with the manufacture rights sold to Wajax. From my googling, this engine sure isn't as common with parts, literature, etc. as the Briggs & Strattons I am more used to.

trinik7597 said:
rotax is a very popular motor with some friends of mine who race flat track they switched them out instead of hondas years ago for reliability and they still rebuild them so parts must be available
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MoTo-BunnY

MoTo-BunnY

Member
#9
#9
that kart is awesome! that expansion chamber on the muffler is huge. ..lol would love to hear it run.

We haven't tried to start ours yet, trying to find an operation manual and/or service manuals first. Looks like it has a compression release or something on it? not sure. .. . not used to 2-cycle world.

roccosbike said:


318CC on a margay, pulls hard outta the hole.Basically the same engine,this one is off a 69 Ski Doo "OLY"
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MoTo-BunnY

MoTo-BunnY

Member
#10
#10
Just curious if anyone else has anything to add about these engines? I would still love to have any kind of literature on this engine as I only have a rough parts manual, at this time.

Also, can anyone ID the carburetor type? It seems to be a diaphragm type and while the above stats on Wikipedia state they use Tillys, I'm not sure about this engine being that it is much older? I will get some better pix tomorrow and see if I can find any numbers......
 
bikebudy

bikebudy

Banned - Must pay $500
#11
#11
Engine looks like it could have been used on a large chainsaw also.

Rotax never used this size in a snowmobile, so I can't add a hole lot.

Looks like it would be a kool kart engine.

http://www.ultralightnews.ca/rotax185/185parts.htm

just what I found

ROTAX SHOP HAS 185 parts

Bob Robertson
Light Engine Services Ltd.
Rotax Service Center
Aero Control Enterprises, Inc.
St. Albert, Ab. T8N 1M8
Ph: (Tech Support) 1-780-418-4164
Ph: (Order Line) 1-866-418-4164 (TOLL FREE)
 
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MoTo-BunnY

MoTo-BunnY

Member
#12
#12
bikebudy said:
Engine looks like it could have been used on a large chainsaw also.

Rotax never used this size in a snowmobile, so I can't add a hole lot.

Looks like it would be a kool kart engine.

Rotax 185 parts, Rotax 185 engine parts.
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Seems like it would have to be a pretty big chainsaw? Did they really make them that big? (maybe to cut down old-growth trees?)

As far as I can tell, this engine was pretty much used for water pumps, ultralight aircraft, and a few karts. Seems like it would be an incredible mini engine, given the 2-strokes power to weight ratio. I love the sound of 2-strokes too-like angry bees in a can!

thanks for that link but that is the ONLY literature I seem to be able to find on this engine........parts sources seem to be real limited too, unfortunately, for some reason? :shrug: I wonder if "Bob" is still the man for parts on these? (I saw that also! :) )

Here are a couple of examples used in aircraft (seems like that means it has to be pretty reliable? lol):


 
Boomstick

Boomstick

New Member
#13
#13
Christ, that almost qualifies as an entry-level commuter bike engine!


I'd rock that on a board track racer... I don't know how well it would fare on a minibike though... might be kind of peaky for that application.
 
MoTo-BunnY

MoTo-BunnY

Member
#14
#14
Boomstick said:
Christ, that almost qualifies as an entry-level commuter bike engine!


I'd rock that on a board track racer... I don't know how well it would fare on a minibike though... might be kind of peaky for that application.
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What do you mean by "peaky"? I was kinda concerned that this type engine is designed to run at a steady RPM? (like in a water pump or an ultralight). Is that kinda what you mean?
 
Boomstick

Boomstick

New Member
#15
#15
MoTo-BunnY said:
What do you mean by "peaky"? I was kinda concerned that this type engine is designed to run at a steady RPM? (like in a water pump or an ultralight). Is that kinda what you mean?
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Kind of, I'm just thinking that it would be a complete dog until it hit its powerband wayyy up there like most 2 strokes & then it's just a matter of hanging on.
 
C

chazdaddy

New Member
#16
#16
That is a very cool engine. 185cc and only 9hp, might be pretty nice on minibike, but too much for me.

I used to race 125cc Rotax FR125, 28hp. The fastest I ever went in a kart, was clocked at 100mph at Texas World Speedway once.

Only problem I see is $'s for parts. My experience with Rotax, very expensive.
 
MoTo-BunnY

MoTo-BunnY

Member
#17
#17
Boomstick said:
Kind of, I'm just thinking that it would be a complete dog until it hit its powerband wayyy up there like most 2 strokes & then it's just a matter of hanging on.
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OK. . .that makes sense. We have never really worked on 2-strokes, so that whole world is new to us. I have seen some that really rip though, for sure!

We were thinking about making a drag bike mini next and this engine was looking real interesting for that use. We will see. . .might pass it on and focus on the Briggs and Tec engines which we are already really good with and have a few of and lots of parts.
 
MoTo-BunnY

MoTo-BunnY

Member
#18
#18
chazdaddy said:
That is a very cool engine. 185cc and only 9hp, might be pretty nice on minibike, but too much for me.

I used to race 125cc Rotax FR125, 28hp. The fastest I ever went in a kart, was clocked at 100mph at Texas World Speedway once.

Only problem I see is $'s for parts. My experience with Rotax, very expensive.
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wow, that is fast for a kart! I bet it sounded crazy too, with a screaming 2-stroke engine. :thumbsup:

It does seem like parts are available but only from few sources and looks to indeed be pretty spendy. It's not like the Briggs parts we are used to, for sure, being pretty inexpensive and all over the place.
 
toomanytoys

toomanytoys

Well-Known Member
#19
#19
I'd bet the powerband is very narrow like Boomstick said. If in fact that motor is designed to run at a constant, so 6,000RPM(pulling the number out of my rear) and make 9HP, at 5000 you are probably making 4.5, 9 at 6000, then it will fall on its face.

I'm no expert in 2 stroke tuning, or pipe design. But I read a few articles linked off of this website with guys designing their own 2 stroke pipes using some fancy math and changing the power band on their engines.
 
C

chazdaddy

New Member
#20
#20
2 cycles can be designed and tuned to have wide power bands, make power at lower rpms, just like 4 cycles. Just don't know how this engine was designed to run.

185cc and only 9hp is low performance 2 cycle. I suspect it has broader power band and more user friendly than you might suspect. :shrug:

The pump is using 2 cycle power, just like chain saws, because of better power to weight ratio. Can you imagine carrying a 9hp Briggs plus the pump on your back, hiking to the fire? :laugh:
 
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