Porting a Sachs Wankel

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motorman45
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Porting a Sachs Wankel

#1 Post by motorman45 » Tue Dec 04, 2018 10:10 am

I thought some of you here may like to see and hear the ported Sachs 303's ive been building. these Peripheral port charge cooled and air cooled engines that were used mostly in snowmobiles from 68-72. there were 30,000 of these installed in Arctic cat sleds over these years and aa 295 later on but not many. I live where there is a lot of snow so ill get a chance to test and tune it some more. I may post some of it in action later when there is more snow on the ground.
anyway ive ported a few of thee and this is my latest. please comment.
Attachments
porting 4.jpg
porting 1.jpg
IMG_20181015_164845276.jpg
assembled motor.jpg
33mm HR tilly .jpg
32.jpg
3ed vs stock porting.jpg
These users liked motorman45's post (total 4):
WANKfactor (Tue Dec 04, 2018 7:14 pm) • M10A (Tue Dec 04, 2018 7:31 pm) • Slides (Thu Dec 06, 2018 11:38 pm) • Sachs Man (Sun Dec 09, 2018 11:51 pm)



spunbearing
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Re: Porting a Sachs Wankel

#2 Post by spunbearing » Tue Dec 04, 2018 2:08 pm

Nice work

Porting is different on rotary engines, not really about making them all round bigger, more about port timing. You should try opening the trailing side of the port only, you will get a stronger higher reving engine.

What is this thing you call snow?



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Re: Porting a Sachs Wankel

#3 Post by MIK20B » Tue Dec 04, 2018 2:10 pm

AWE.......SOME!!!!!
ANY MORE VIDEOS?
ANY MORE PHOTOS???



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Re: Porting a Sachs Wankel

#4 Post by WANKfactor » Tue Dec 04, 2018 7:13 pm

Sound strong! What sort of power do you think its putting out? I love it.


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Re: Porting a Sachs Wankel

#5 Post by motorman45 » Tue Dec 04, 2018 11:31 pm

Im glad you guys like it. this is the third go at porting one of these. i had a bunch of motors and wanted to d something different than 2 strokes in a vintage sled. i hear ya about the port timing. i did try just opening the trailing edge but these motors have such small ports i didnt realize much power gain till i gave it some real port area and made a custom intake and got a 34mm cab on it. came with a 25mm carb stock.
the porting is limited by the thru bolt locations mostly. stock these were rated at 20hp at 5500rpm. i have two sleds with ported engines now, the first one here https://vintagesleds.com/bs/index.php/t ... 738.0.html peaks out at 6700 on a flat field but will rev to 7k on a long run on the lake ice. the latest port job i kind of went as far as i think i can given the casting limitations. my guess is im putting out 26~28hp on both of these motors, maybe closer to 30 on the latest when i get the clutching dialed in. CVT clutching is key on sleds to get all the power to the track.
here is another vid of the first ported motor, this custom exhaust sounds really good and seems to help the output when i got the carb tuned in. the carb on all these engines are Tillotsons, like used on race karts, just bigger, adjustable high and low needles. there are more videos on my channel




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Re: Porting a Sachs Wankel

#6 Post by Slides » Thu Dec 06, 2018 11:42 pm

If they are just fixed timing magneto ignition you could probably get heaps more power and revs with programmable ignition to go slong with the ports and bigger carbs. Is there any throttle advance like 2 stroke boat motors?



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Re: Porting a Sachs Wankel

#7 Post by motorman45 » Sat Dec 08, 2018 8:24 am

The timing is fixed in these motors at 10-12 deg stock. ive played with it at 15 and 18 deg with minimal diff. ive thought about adapting a cdi to it but from what ? i know there are custom retro-fit cdi units for old sachs 2 stroke race engines, i may be able to make something like that work,
im not sure how much output these motors could stand and stay reliable. if i get 30-35 hp thats a big increase from the 20hp they start with and enough to move my 320lb sled well over 60 mph on snow.
i have read and searched for ideas on this and other rotary sites for a while before i started porting these.



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Re: Porting a Sachs Wankel

#8 Post by Slides » Sun Dec 09, 2018 2:31 am

Bringing in more advance should just maintain torque for longer, not introduce additional load, although obviously the bearing loads from any out of balance in the rotating assembly will increase. It should allow more top speed without sacrificing bottom end but that may not be a significant issue with your clutch arrangement and if porting is limited. It may be helpful for fuel economy when not at WOT too.



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Re: Porting a Sachs Wankel

#9 Post by Sachs Man » Sun Dec 09, 2018 11:49 pm

motorman45 wrote:
Tue Dec 04, 2018 10:10 am
I thought some of you here may like to see and hear the ported Sachs 303's ive been building. these Peripheral port charge cooled and air cooled engines that were used mostly in snowmobiles from 68-72. there were 30,000 of these installed in Arctic cat sleds over these years and aa 295 later on but not many. I live where there is a lot of snow so ill get a chance to test and tune it some more. I may post some of it in action later when there is more snow on the ground.
anyway ive ported a few of thee and this is my latest. please comment.
Nice work you have done on the 303's I have a couple of KM24s that i will get up and running soon, one of them had a stuck apex seal, got it loosen up but one of the side seals was rusted in the rotor and i broke the seal when trying to remove it :cry: :cry: I got some parts coming from the US new side seal,new corner springs Man there not cheap. How do you go with getting parts for your sachs engines?



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Re: Porting a Sachs Wankel

#10 Post by motorman45 » Mon Dec 10, 2018 1:53 am

Thanks Sachs Man. these motors area lot of fun and have the best sound of any small engine ive messed with. i have been looking for a KM24 but they made much fewer of those so not many around. its great you found seals, not always easy. i like the 295 km24 as its got bigger ports but has a side intake and peripheral exhaust, i wondered about porting that motor some.

the way ive found parts is to buy entire old sleds and pull the motors apart. surprisingly ive gotten seals still in spec from 3 used motors and it was cheaper than what i see seals alone go for. having a bunch of spare housings laying around is what inspired me to try porting. ive done it gradually mostly on 2 different housings to the point im at now. Arctic cat put over 30,000 of these 303's in sleds so in the snow belt where i am i see them from time to time.

What are you putting the km24 in ?? ive seen a kart on youtube setup with one but he only had it set with a fixed gear, no cvt like a sled or gearbox. these engines work well with the cvt with all the torque they have



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Re: Porting a Sachs Wankel

#11 Post by Sachs Man » Mon Dec 10, 2018 4:48 am

motorman45 wrote:
Mon Dec 10, 2018 1:53 am
Thanks Sachs Man. these motors area lot of fun and have the best sound of any small engine ive messed with. i have been looking for a KM24 but they made much fewer of those so not many around. its great you found seals, not always easy. i like the 295 km24 as its got bigger ports but has a side intake and peripheral exhaust, i wondered about porting that motor some.

the way ive found parts is to buy entire old sleds and pull the motors apart. surprisingly ive gotten seals still in spec from 3 used motors and it was cheaper than what i see seals alone go for. having a bunch of spare housings laying around is what inspired me to try porting. ive done it gradually mostly on 2 different housings to the point im at now. Arctic cat put over 30,000 of these 303's in sleds so in the snow belt where i am i see them from time to time.

What are you putting the km24 in ?? ive seen a kart on youtube setup with one but he only had it set with a fixed gear, no cvt like a sled or gearbox. these engines work well with the cvt with all the torque they have
Yeah i was thinking of using the second motor for parts,but found a chap who sells spares. I miss out on ebay there was 6 x sets of side seals and springs for $279 usd Ebay come up with KM24s for sale from time to time, you just got to keep a eye on it. I also have a brand new short block km48 so looking out for a complete km48. Yes there was a chap named Bret Stephensen who had videos on the KM24 go kart plus a lot of tips on the engine . I also was chatting to him by email and now he has disappeared all youtube vids are gone and i can not send emails to him anymore.
I think i would like to fit the KM into a motor cycle frame. I have started a topic on the km engine in the Tech talk page viewtopic.php?f=4&t=251169
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A-Short-History-of-Wankel-Motorcycles-The-Vintagent-bsa.starfire.jpg



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Re: Porting a Sachs Wankel

#12 Post by green200b » Mon Dec 10, 2018 7:22 am

Awesome! A rotary snowmobile sounds like a lot of fun!


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Re: Porting a Sachs Wankel

#13 Post by motorman45 » Mon Dec 10, 2018 10:44 am

Sachs Man wrote:
Mon Dec 10, 2018 4:48 am
Yeah i was thinking of using the second motor for parts,but found a chap who sells spares. I miss out on ebay there was 6 x sets of side seals and springs for $279 usd Ebay come up with KM24s for sale from time to time, you just got to keep a eye on it. I also have a brand new short block km48 so looking out for a complete km48. Yes there was a chap named Bret Stephensen who had videos on the KM24 go kart plus a lot of tips on the engine . I also was chatting to him by email and now he has disappeared all youtube vids are gone and i can not send emails to him anymore.
I think i would like to fit the KM into a motor cycle frame. I have started a topic on the km engine in the Tech talk page viewtopic.php?f=4&t=251169
[/quote]

good to know there are still sources for seals. too bad bret pulled the videos, I like that Norton , ive read all about them basing their later rotary bike engines off of the sachs 303 tests like in that pic.

these are Great engines for a snowmobile. nice wide torque curve. Sachs developed some hot version of the 303 in i think 69 or 70 that put out 40hp, were put in some race sleds back then and cleaned up at snowcross that year and then were banned from sled racing. they also were working on water cooled versions but for some reason wanst enough to keep them going.
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Re: Porting a Sachs Wankel

#14 Post by Sachs Man » Mon Dec 10, 2018 2:04 pm

motorman45 wrote:
Mon Dec 10, 2018 10:44 am
Sachs Man wrote:
Mon Dec 10, 2018 4:48 am
Yeah i was thinking of using the second motor for parts,but found a chap who sells spares. I miss out on ebay there was 6 x sets of side seals and springs for $279 usd Ebay come up with KM24s for sale from time to time, you just got to keep a eye on it. I also have a brand new short block km48 so looking out for a complete km48. Yes there was a chap named Bret Stephensen who had videos on the KM24 go kart plus a lot of tips on the engine . I also was chatting to him by email and now he has disappeared all youtube vids are gone and i can not send emails to him anymore.
I think i would like to fit the KM into a motor cycle frame. I have started a topic on the km engine in the Tech talk page viewtopic.php?f=4&t=251169
good to know there are still sources for seals. too bad bret pulled the videos, I like that Norton , ive read all about them basing their later rotary bike engines off of the sachs 303 tests like in that pic.

these are Great engines for a snowmobile. nice wide torque curve. Sachs developed some hot version of the 303 in i think 69 or 70 that put out 40hp, were put in some race sleds back then and cleaned up at snowcross that year and then were banned from sled racing. they also were working on water cooled versions but for some reason wanst enough to keep them going.
[/quote]
Here is a pic of a Sachs powered dirt bike and a some vids of custom sachs wankel bikes.





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Re: Porting a Sachs Wankel

#15 Post by motorman45 » Tue Dec 11, 2018 1:46 am

Really cool bikes. It is amazing how many vehicles used wankel motors besides mazda's. its still surprising to me how it has not been used more widely. john deere ( the tractor co) bought out the OMC rotary engine tooling and developed a whole range of wankels for tanks and tractors and then sold all the development, tooling and rites to whats now freedom motors. https://freedom-motors.com/ this guy has been truing to build flying cars forever, but im not sure where hes at now.
i will have some new video to post of the sled running across snow soon.



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