Paul,
I thought I might give you an update on my project / progress. I've added some pics
at the end.
I ran across a guy on Craigslist who had 4 old Arctic Cat Snowmobiles with Wankel
engines for sale ...Sachs KM 24 engine...295 CC. I knew one would run for sure
because we sprayed gas in the carburetor and fired it up for about 30 seconds. I
bought the rest of them not knowing for sure what I would get. 1 had compression,
the other two did not.
Well, I got them home and started tearing down the three engines that did not run. I
also tore all 4 carburetors down, cleaned them up, and put them back together.
They've been sitting so long that the Varnish in the carburetors was actually
powderized. Also there was some oxidation of the aluminum carburetor housing.
I decided not to tear down the one engine that I had test-fired. I used it to test
the carburetors and they were all working fine except one had a leak that I need to
fix... Not sure what it is, probably a gasket.
But I did have some problems with the ignition...losing spark...arcing at the
points... I had to file a few times... I finally realized it was because of bad
connections at the coil and the plug terminal due to age. I replaced the plug wire
and terminal/boot... it's been fine ever since.
Also... I had problems with the plug gap... Supposed to be .020, but every time I
pulled it out, it was at 10-15. Then I noticed a shiny wear spot on the end of the
electrode... it was getting hammered by the Apex seal! What? I ended up having to
add 3 extra spark plug washers to back the plug out to where it would no longer get
hammered by the Apex seal.
I thought this was really strange, because all three other engines that I tore down
had the same spark plug but the electrode was recessed about a quarter inch from the
housing face. I wondered what was going on until I noticed that for some reason the
top of the spark plug hole is different... The other three engines have an extra
quarter inch of material extending up from the outer surface of the housing which
leaves you with an extra quarter inch of threads in the hole. Not sure why they did
this ... same model of engine...different year, maybe? Perhaps it was because the
Wankel could then use a standard BR8ES 2-cycle snowmobile plug instead of its own
oddball... or maybe the previous owner had it modified...cut down to get the plug
closer to the Apex seal....don't know.
There were a few other problems... plugged Muffler, rusty/siezed clutch, stuck choke
and throttle cables.
Well finally, I was able to get the engine to start and run consistently. BEAUTIFUL!!
One pull starts. Purrs like a kitten when it's idling. Video attached.
As for the other three engines, I've got them all torn down and in various stages of
cleaning them up, soaking the parts in diesel fuel or carb cleaner to loosen up the
Carbon. I was a bit worried what I would find when I started. Turns out, one of them
looks brand-new inside... the seals fell out as I removed the rotor from the housing.
Stored with oil in the cylinder... Must have been a farmer... They were kernels of
corn stuck in the air fins ... mice I suspect...lol.
The second engine took a bit of soaking to get all the seals and Springs apart from
the rotor... But after cleaning they seem to be in good shape... And still within
spec so they can be reused.
The last one was the worst, lots of chipping/pitting on the Apex seals... and it took
a lot of work to remove the side seals... soaking, prying, and a bit of hammering...
three of the six didn't make it out in one piece.
The good news is, the housings and the end plates are all in really good shape. The
trochoid surfaces all have a nearly mirror finish after cleaning them... the worst
one which I've shown in the attached pictures has some stubborn stains that might be
a bit of pitting but feels more like really stubborn rust cake... These have been
sitting for years with water in them I think.
The end plates look rough at first glance. There's a few minor scratches from turning
the engine over with Rusty gunk in it. But after wiping it down with carb cleaner,
there's really no grooving or motion related wear. Just a bit of what I think is
minor pitting...could be milled out if necessary.
All in all, I'm quite happy... even the worst engine can be cleaned up and made to
run... And it's in rough enough shape that I won't feel bad about cutting into it to
make my modifications to test my ideas.
I'm about at the point where I need to start thinking about building my dyno test
bench... I don't know if I already told you this, but I figured out how to make an
adjustable load dyno using an old torque converter. First step is to get one of
these engines back together and mounted on a solid platform for running/testing.
Here's a link to my Google Drive folder where I'm keeping a few more videos and pics.
https://drive.google.com/folderview?id=1VcTzC_zkgzKY60b5oKvfWwg8bAOzbKYa
Ethan Stinar
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