wvl

Are there any issues to mount a 2-stroke engine using the 4 cranck case cover thread holes? Is there a risk that the cranck case will break?
Some engines don't seem very robust near these cranck cover thread holes. I would like to mount the engine to a flat plate, and mount that plate with rubber isolators to the firewall.

I just don't wont to see my engine take off without wings.

Thanks guys,

WVL

jacs

Have you seen anybody mount their engine that way?

The screw are to small for this job I think.

FHHuber

The screws are marginal for the purpose on most sport 2 stroke engines.

You would HAVE to use longer screws to catch sufficient threads in the case to prevent striping out the screw holes in the case.

You would be asking to break out the sides of the screw holes in the engine case, as the casting is not designed to take the loads you would be imposing.

There ARE some engines that are designed for this type mounting... but most of the common engines would not tollerate it.

Tall Paul

K&B makes a mount exactly like that for the .20/.28, and maybe the .40.. It replaces the back plate and has 4 legs to support the motor.
It is somewhat fragile, but works OK.
Many people have added flat plates to back covers for this type of mount. Relieve the plate a bit on the back so the screws are flush against the firewall.
Here's the K&B, and two custom mades..

wildnloose

You may want to look at one of those "go fast" mounts that pylon racers use and see if it will work...

Ed Smith

For our .40 size Pylon Racers we us a backplate mount. The engine of choice is the Nelson N40. It revs at about 19,000 and generates nearly 3HP. It pulls a 3.5# airplane along at 150 mph. The backplate mount is made by Nelson for the engine. It replaces the rear cover. It is held on by four #5-40 screws. I have never broken or seen a broken crankcase because of this type of mount. I have had some very bad crashes. It is not an issue and do not listen to those who say it is.

Ed S

LouW

Seem like this question was also posted in the engines forum. The attached photos show an example. I got this engine with some traded stuff, and the mountung lugs were ground off. The engine appeared to be new. I made the backplate and it has been quite durable.