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Discussion Starter · #1 ·
Hi. This seems to be the place that experts on the vintage Sachs motors hang out. I'm new to these motors, but am in I the position of having to bring one back to life, or find a suitable replacement.

My first question, having done some research, is whether there are any actual differences between the Sachs KM914B and the Curtiss-Wright 1-18.5 -1 motors (also built by Sachs), or is the CW motor just a re-badge of the KM914B, such that all parts or the entire engine would interchange?

My other questions would be the usual ones you see from rotary newbies looking to tackle this, e.g. where NOS apex seals etc. can be scrounged, but my general impression is that requires a combination of patience and eBay. The scarcity and price of parts for these engines is shocking, with the cost of a set of apex seals about equivalent to the price of a running used vintage sled. Thus my question as to whether the CW (Sachs) engine is actually the same as the KM914B as to what parts will interchange. I have a rebuild manual for the KM914B and it never mentions the CW motor.

Thanks in advance for any info on this. I have been unable to find this out anywhere so far. bang your head
 

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I'll admit I'm of no help, although your post has peaked my curiosity. What were some primary uses of the CW 1-18.5-1 motor? Perhaps knowing the uses would get the ball rolling to possible sources of information?
 

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After doing a lot of book worm digging over the past several years, here is the scoop:

CCW imported the wankel motor into the states and Canada for Sachs in the early days. The wankel crew for Sachs consisted of a measly 17 guys, gearheads and engineers. Not exactly a monster tech team. I get the impression they were almost a separate entity in the corporation. The KM914 was made over the years in three different versions that made it into sleds. The KM914 A model had a little more ****, 20 to 24 hp, depending on who you asked. It had to do with the way the intake was routed. Arctic went with the B model, because it's intake was routed best to fit in the Cat chassis of the day. The A model would have been bassackwards I guess and hard to fit cleanly. The early B model had a smallish intake port and only put out 18.5hp around 5000 rpm. That engine Cat used from 1968 to 1970 in the Panther and the leftovers wound up in the early 1971 Lynx 303 run. Cat made a running change to the larger port B model that put out a true 20hp and they were worked into the 1971 Panther run, and all the 1972 Panthers used that engine. It is almost impossible to tell the difference between the two based on appearance. It's a real subtle thing to look for. Better to go with the serial number on the blocks. I can't remember that off the top of my head, but I do have the numbers at home. They did also make a twin rotor 606 based off this engine that put out 35hp stock. Arctic is supposed to have recieved about 6 of them for testing, with the idea that they would order more if it worked ok.
They were stuck in a few 1968 sleds. One was raced with some minor success, but the engine had some teething pains, ran hot, and was probably expensive to build, so that was as far as it got. Polaris and Scorpion were also courted by Sachs as customers for the 606, same results. The engine was like an answer for a non- existant problem and just died on the vine. But the 303 single and the later 1973 to 1975 KM24 295 got fans for being smoother than a 2 stroke single of the same size. Women and kids like them because of that, locally we sold a bunch to farmers because the sled would idle all day long when dialed in right, which made it great for taking a couple bales of hay out to the cows. It also is a fairly light engine as compared to other early beefy bangers of the period. That's about all I can tell you.

PS: I avoid the title of "Expert" like VD. :super_happy:
 

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<div class='quotetop'>QUOTE (gbarchives-eltigre @ Jan 10 2007, 04:08 PM) <{POST_SNAPBACK}></div>
PS: I avoid the title of "Expert" like VD. :super_happy:[/b]
How about "All-knowing God of all that is Arctic Cat?" :Not worthy: :D
 

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I can't help you, but dad had a 1968 Panther with a Wankel and it was his favorite machine, probably just because it was "different".

I also know he has been inside a few of them (he used to work at an AC shop part time) so if you had some mechanical questions I could ask him for you. That being said I know he doesn't have a clue where you can find parts for them.

He said they where super smooth, tons of torque but ran real hot (the manifold would glow from what I hear) and they liked to consume fuel at a higher rate then other engines of that time period.

K
 

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I'd agree on the hot exhaust. It's an old joke amongst vintage sled heads to race a group of wankels across a lake and see who can light a cigarette off the glowing stainless header. The 303 header would glow if the sled was run hard and also jetted lean. The engine can burn down, like a two stroke, if run too lean. I jet mine on the "as rich as I can run the thing" side, use good fuel and synthetic oil. Still don't freak out if the header glows in the dark after a 10 mile flat out run. If the thing is glowing all the time, yeah then freak out. This means either the jetting is too lean or the timing is too far advanced. Timing creep is something the later KM24 engine was famous for. Other funky problems the engine had, were some would allow chaff from the fields to creep into the points and burn onto them. Then the engine ran like crap. Dad only had one, a 68 or a 69, do this. I remember my 71 and 72 did not do this. But the big beech with the '72's is the hood allows snow to blow right into the carb if you go powder busting. That makes it choke off and ice up. The other problem was the Tilly HL carbs can be an annoying POS. They run good for about a year or two, then need a complete rebuild. I have hit that time again with my '72. I am thinking about going with a HR/GEM hot rod intake swap. Gives it a bigger carb, more power, less chance for icing if I make a hot air snorkel rig that takes warmer air off the block. We did this mod back in 1974 and it did help a similar sled I had back then. GEM is long out of business, but the manifold adaptors show up at swap meets every now and then. The carb we use is a HR off the Kawasaki 292.
If my memory is right, I think it added about 5 mph on the top end, and power in the upper mid range to top.
That sled would walk up a tree as far as hillclimbing goes, with that 17 inch wide cleated track and three feet of it on the ground, if you threw on about three boxes of Kalamazoo super claws.

Several years ago we had a blizzard that dumped three feet of powder out here. My neighbors new sleds kept freezing up and could not break trail. I kept stopping every 30 minutes to let the carb thaw out, but the old wankster would not get stuck! About the only sled running that night. :super_happy:
 

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Discussion Starter · #7 ·
Thanks for all the great info - explains the Curtiss Wright RC1-18-5 vs KM914B question. I also found a page that lists specs for both models as if they were pretty much the same.
http://www.blackcats1.homestead.com/sachs_wankel_303_01.html

Dumb follow-up question on the KM914 - I am trying to find the right bolts to bolt the KM914 into the Panther mount (the bolts run into the block into blind holes). I have a Sachs rebuild manual for the KM914 that clearly shows these are M10-6H bolts, so I go down to the local Home Depot and get myself some 10MM coarse thread bolts and they are too big. 8MM bolts are too small. I tried an SAE bolt that is in-between and it sorta-kinda goes in OK (I was being careful-hand turning only) but the threads don't look too happy about it ( I can't tell whether someone abused the threads before I got the engine or not). I'm not brave enough to try this on another hole before I can get some confirmation as to why the M10 spec in the manual seems bigger than the actual hole in the block. Can anyone confirm the bolt / thread size?
 

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Discussion Starter · #8 ·
False alarm (sorta) about the mounting bolts. Seems like the problem was indeed that someone had run an SAE bolt into the hole and messed up the threads such that the correct 10mm bolt appeared to bottom immediately. Once I chased them back into shape with a tap the 10mm bolt fits Ok with hopefully not too much loss, and i have checked it against one other hole. The other holes appear unmolested(or at least so far full of too much gunk too tell yet).
 

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An old cat dealer told me he loved Wankel's but they love fuel and you'd better keep some sort of filter on them because if they suck up any dirt, it will score the assembly inside and she'll be all done!
 
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