Rotary Engine Chainsaw

[Vintage Engine Repairs]

Hi,

I’ve just found out Dolmar and Yanmar made rotary engine chainsaws in the 70’s. Has anyone ever used one here or worked on one?

I’m interested to find out more about what they were like, reliability and how they were to work on?

My experiences of hearing / seeing rotary’s are more in line with this…

 

[leeha]

I own the Dolmar KMS-4 rotory saw. They are very smooth. Power is equal to a 60cc saw in the same time era.
It's a collectors saw today and not all that many around. I have never seen the Yanmar but i have heard of them.

 

[Vintage Engine Repairs]

Very

I own the Dolmar KMS-4 rotory saw. They are very smooth. Power is equal to a 60cc saw in the same time era.
It's a collectors saw today and not all that many around. I have never seen the Yanmar but i have heard of them.

Very interesting! Have you done any repair work on them? If so, how did you find it to work on? Do you still run it occasionally or is it just on the shelf?

 

[KASH]

Sachs recalled and destroyed theirs.Here in ThunderBay there was a outboard dealership in business since 1939 he had a never run one for sale .he wanted 995.00 for it but on the last day the open closing due to bankrupt he would not come down.It closed about 6 years ago it was amazing there was millions in old inventory he had parts and manuals for everything imaginable a crime what on line gambling does.
Kash

 

[Old2stroke]

Be interesting to know what type of carb they used. Rotary engines on snowmobiles had problems with reliable fuel delivery because the impulse signal wasn't strong enough to provide adequate pumping action in a regular pumper carb.

 

[leeha]

Very
Very interesting! Have you done any repair work on them? If so, how did you find it to work on? Do you still run it occasionally or is it just on the shelf?

I have never worked on any, Mine is more or less a shelf queen but it does get run at gtg's.

 

[ken morgan]

@SEAM has a couple of them down on the lower part of Izu peninsula... meaning to drive down their one day to look at his collection and play a little with the saws.

 

[leeha]

Seam is a very good person. We had a few dealings a few years ago.

 

[heimannm]

I only took mine down far enough to give it a good cleaning. The carburetor is a conventional Tillotson HS if I recall.

They are a bit heavy for the displacement but they are very smooth and have a distinctive sound . Mitch Weber (Mweba) has taken a few completely down to replace the rings/seals, I am not sure if he made any posts here but may have made a You Tube video.







There is no real flywheel, rotor provides adequate rotating mass, the fan does move a good quantity of air across the cooling fins.

As with most, mine had the hand guard missing when I receive it. Some sent a like new unit through the shop to change the ignition so I borrowed his hand guard long enough to have my Engineer friend make a drawing so I could reproduce them with the 3D printer.







Mark

 

[Vintage Engine Repairs]

I only took mine down far enough to give it a good cleaning. The carburetor is a conventional Tillotson HS if I recall.

They are a bit heavy for the displacement but they are very smooth and have a distinctive sound . Mitch Weber (Mweba) has taken a few completely down to replace the rings/seals, I am not sure if he made any posts here but may have made a You Tube video.

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There is no real flywheel, rotor provides adequate rotating mass, the fan does move a good quantity of air across the cooling fins.

As with most, mine had the hand guard missing when I receive it. Some sent a like new unit through the shop to change the ignition so I borrowed his hand guard long enough to have my Engineer friend make a drawing so I could reproduce them with the 3D printer.

View attachment 952734

View attachment 952735

View attachment 952738

Mark

Awesome thanks for sharing all that info Mark, they sure are interesting!!

 

[rarefish383]

Don't know how I missed this thread way back when. Was playing around on the internet and saw it, and had to click on it. I know it's old, but I'll throw mine in there too. Thanks to Mark for hooking me up with a hand guard, mine was broken too.

 

[Oliver Mulliss]

I’m going to jump on this thread, I’d love to have one of these saws. Does anyone have one for sale? Preferably in the uk. Thanks.

 

[Jasonrkba]

Interesting, sounds like a slow runner. Different animal to work on I bet.

 

[heimannm]

Even with the hardnose bar and my sloppy technique (two down cuts rather than down/up), my KMS5 was pretty competitive against other 60cc vintage saws.



Mark

 

[rarefish383]

Interesting, sounds like a slow runner. Different animal to work on I bet.

8 HP at 8,000, 58 CC's. Bet it will out cut a lot of 50-60 class saws.

 

[rarefish383]

8 HP at 8,000, 58 CC's. Bet it will out cut a lot of 50-60 class saws.

Thanks Mark. I didn't see your post first.

I’m going to jump on this thread, I’d love to have one of these saws. Does anyone have one for sale? Preferably in the uk. Thank

Make me an offer? PM if you want to keep it private.

 

[sawfun]

My old KMS-4 sounded really strong but cut the same speed as my 3.7 Poulan, which weighed a lot less and cost $100 compared to the $$$. The rotary's are also a serious fire hazard in the woods. Great collector items, but thats about it.

 

[heimannm]

 

[Bill G]

I like mine.