Sachs KM24 Tear down inspection

[Desertduler]

Time to take a look inside one of my rotary engines and see how it has held up under my abuse.

 

[Desertduler]

https://www.youtube.com/watch?v=rKkF4tOYv4A

 

[landuse]

Man!! Those engines are beautiful inside

 

[Desertduler]

Man!! Those engines are beautiful inside

Yes they are indeed.

 

[Desertduler]

https://www.youtube.com/watch?v=t2RG9a-xjAg

 

[Desertduler]

https://www.youtube.com/watch?v=7pv_wsMk8HA

 

[Desertduler]

I know this stuff is not really common on this site but I hope a few of you find this engine interesting as the rotary engine is pretty much dead. This engine is a 1974.

 

[itsid]

Well, you got me drooling over those Wan'kel engines
(really that word censored is not to my liking...)
This little old computer struggles with html5 videos for some reason (well video ram buffer )..
long story short:
When I watch your videos I'm usually not logged in to diygk to comment directly,
and when back I usually forgot what I wanted to ask (the getting older thing and such)

But that doesn't mean I don't love watching you tear down these engines
(Know what... next time I'll take notes or you'll see me pop up on yt )

'sid

 

[Desertduler]

Well, you got me drooling over those Wan'kel engines
(really that word censored is not to my liking...)
This little old computer struggles with html5 videos for some reason (well video ram buffer )..
long story short:
When I watch your videos I'm usually not logged in to diygk to comment directly,
and when back I usually forgot what I wanted to ask (the getting older thing and such)

But that doesn't mean I don't love watching you tear down these engines
(Know what... next time I'll take notes or you'll see me pop up on yt )

'sid

I know that you like these old relics partially because they are a invention from your homeland! You know I love German craftsmanship and I cherish all of my German and Austrian engines and technology!

 

[landuse]

I love rotary engines. They are so simplistic.

 

[bob58o]

I bought a minibike with a clone engine for one of my nephews. I pulled the plug and was surprised to see it was a shorty. I spent quite a while trying to figure out why they were using that plug. After finding no reason (the engine was completely stock), I replaced it with a longer one. The shorter plug has to bump up your chamber volume about a CC and like you said, with the shorter plug - the burn isn't going to be as good. Their mistake just meant free power for me when I corrected it.

Anyway, awesome stuff as always.
Super clean. Not what I would expect a 1974 'anything' to look like.

 

[Desertduler]

I bought a minibike with a clone engine for one of my nephews. I pulled the plug and was surprised to see it was a shorty. I spent quite a while trying to figure out why they were using that plug. After finding no reason (the engine was completely stock), I replaced it with a longer one. The shorter plug has to bump up your chamber volume about a CC and like you said, with the shorter plug - the burn isn't going to be as good. Their mistake just meant free power for me when I corrected it.

Anyway, awesome stuff as always.
Super clean. Not what I would expect a 1974 'anything' to look like.

I too have found other engines with too short of a plug in them. Most certainly in a conventional piston engine you want to have the plug electrodes as close to the roof of the combustion chamber as possible if not protruding into it providing there is clearance between the plug ground electrode and the piston such as the case if the engine has a domed piston.
You don't want a plug that is too long either with the threads exposed in the chamber.
I prefer to have the electrodes where there is going to be atomized air fuel mixture between them so that when the spark occurs at the plug the flame propagation starts when it should otherwise it could be delayed resulting in a late combustion cycle slightly yes but I like dead on. If you indeed find a plug that is too short you can look at a spark plug chart and find different reach spark plugs with the same heat range and choose one that has the correct reach for your needs.
The heat range determines how the spark plug dissipates heat into the cylinder head or in this case the rotor housing. The hotter the heat range of the plug the less of the heat is carried away from the center electrode insulator and visa versa for a colder heat range.

 

[itsid]

I assume, that if one doesn't know what reach plug the engine wants..
one chooses a shorter one to be on the safe side
(not bumping the piston or in your case worse shredding an apex seal).
And that's why a short plug isn't too uncommon to see on used engines.

I guess there are as many "IDK what reach" that used a too long spark plug
but those engines end up at the scrap yard eventually

It's as easy as sticking a narrow wooden stick in the spark plug bore tilt it and measure the distance between the dents if your pinky isn't small enough to feel the threads on your own, I know;
but how many people do that when in doubt?

'sid

 

[NewbCarter]

Kinda offtopic , but is it possible to have "too cold "of a sparkplug ?

Rotary engines i dont really like but are very interesting , and the rotor housing looks like brand new .

 

[Desertduler]

I assume, that if one doesn't know what reach plug the engine wants..
one chooses a shorter one to be on the safe side
(not bumping the piston or in your case worse shredding an apex seal).
And that's why a short plug isn't too uncommon to see on used engines.

I guess there are as many "IDK what reach" that used a too long spark plug
but those engines end up at the scrap yard eventually

It's as easy as sticking a narrow wooden stick in the spark plug bore tilt it and measure the distance between the dents if your pinky isn't small enough to feel the threads on your own, I know;
but how many people do that when in doubt?

'sid

True, being too short is safer by all means and you are absolutely correct.

---------- Post added at 10:32 AM ---------- Previous post was at 10:30 AM ----------

Kinda offtopic , but is it possible to have "too cold "of a sparkplug ?

Rotary engines i dont really like but are very interesting , and the rotor housing looks like brand new .

Yes indeed, too cold of a spark plug tends to foul easier.

 

[Desertduler]

https://www.youtube.com/watch?v=C0aUgoY1mug
Just a update on the reassembly of this engine.

 

[Desertduler]

https://www.youtube.com/watch?v=fwvCkK5f3jM
Here is how I adjust the ignition timing on this engine and this can apply other engines that use the old points ignition.

 

[landuse]

Thanks for the vid. That was interesting

 

[Desertduler]

Thanks for the vid. That was interesting

Thank you for the kind words and the interest.

 

[ezcome-ezgo]

It's fascinating to learn the details of an engine I will probably never have the pleasure of seeing in person. Thank you.