Sachs Dolmar rotary engine

[sedanman]

I have access to a wankel engine Sachs Dolmar chainsaw. It does not currently run though all the parts appear to be there. What do I do with it?

 

[dbabcock]

To start with, I'd be looking for apex and peripheral seals. The weak link in the chain.

The Epitrochoid Kid

 

[SilverBlue]

No really? there's such a beast??

 

[Stumper]

Oh Yeah! they made a 3.5 CID saw with the "Sachs Wankel engine". At 17lbs the KMS4 wasn't exactly a lightweight though.

 

[max2cam]

Talk about a collector's item! Can you post a photo of what the beast looks like?

Of course there was a Wankel Rotary engine motorcycle. Didn't Suzuki build that for a couple years in the 1970s? And who made the Jap car rotary? Was it Datsun? Can't remember for sure. Any others?

 

[Stumper]

Mazda


Mike Acres has a pic over on the Chainsaw Collector's Corner. The specs are kind of eye popping-8 Horsepower!

 

[buckwheat]

It's my understanding that Mazda is again offering a rotary engine in, i think, the MX8.

Out of curiousity, with a high mass rotary moving at what I assume would be fairly high rpms (the cars redline at 9K), is there any "gyro" effect with these saws?

 

[dbabcock]

The RX8, with suicide doors no less, is once again the only Rotary automobile available in the US. The "Renesis" motor makes 250 HP from about 80 cubic inches of swept volume in its two rotors.

Because a saw only has one rotor, the rotating assembly requires some form of counterbalance just like a single cylinder piston engine. This counterbalance doesn't have to be a large as one might think as the crankshaft offset is very small on these things. Also, be aware that for a crank RPM of 9000, the rotor is only turning at 3000 RPM, thus reducing the inertial forces by a factor of 9 right off the bat.

 

[Stumper]

Max operating rpm on the KMS-4 was listed as 8000.

 

[jbrody44]

I have heard that many owners of the new rx-8 have been very upset at the HP output from the car. When run on a dyno they have not been putting down the HP. In fact Mazda has offerd to buy back some cars: See here:


http://www.rx8club.com/showthread.php?s=&threadid=9347]

 

[cuttinscott]

KMS4

hey great find is it for sale i am really interested
let me know if you want to sell or trade maybe for
a new saw thanks Scott.

____________________________________________________

a few dolmars
166 38" 166 alchol and nitro 21"
153 24" 143 mx 29"
133 20" 133super 20"
123 20" 309 demolition 12"
116 super alchol and nitro 18"
ps 7900 20" ps 540 18"
ps 401 14" 102 14"
7314 demolition 14"

 

[max2cam]

Any idea how many of these rotary engine chainsaws were made? Couldn't have been too many...

 

[Stumper]

I don't know the actual number but as you say probably not very many. It retailed for $598 in 1975 --about double the cost of similar displacement saws. Of course if performance was at the level impied by the spec sheet it outclassed all of the similar displacement saws.

 

[sawyer40]

Artic cat also had a snowmobile with a wankel engine

 

[max2cam]

I went to Mike Acres Collector's website but couldn't locate any photos of the rotary Sachs-Dolmar. Anyone have a link?

I did learn that Dolmar got its name because the first one was used on Dolmar Mountain. That was cool!

 

[Stumper]

Is is on the site-the model is KMS-4. The pic is at the bottom of the page-you have to scroll to see it.

 

[Stumper]

 

[McC]

A fellow collector brought one to our Baraboo show a couple of years ago. It has a beautiful throaty sound, and seemed to have pretty good power. My deceased uncle has one, still in the box, never run. He said they were recalled by Dolmar, who disposed of them through a company who was supposed to destroy them. This company sold them liquidators, who sold them to the public. Dolmar dealers were quite surprised to have them show up in their shops for repair, since they were supossed to be destroyed.

 

[HUSKYMAN]

Why were they recalled. Did they explode like the balanced Mac's?

 

[max2cam]

Thanks for the photo.

Good looking saw. Good story on the recall and liquidation sale. Super collector's item too.