Hi
Just wondering what is the best way to install a four stroke to the mount. Is it best to use a nut and bolt, or should I tap and install a bolt? I know four strokes vibrate a lot, so I don't know which is the best.

Thank you for your help.

Handyandy

Really, I don't think there is a best way. It's all a matter of personal preference. I usually mount mine with a sheet metal type screw. It hasn't failed me yet.

I have also used a bolt with a locking nut on a four stroke engine, only to have the nuts back off after a period of time.

My personal opinion..... use the method that suits you best.

Best regards,
Mike

over the years I've had three motor mounts break with sheet metal screws,I've used bolts with washers and locknuts for more than a dozen years with no problems.

My preference is to tap the mount and use a nylock to back up the threaded mount. If the bottom of the mount is not parallel to the top surface, you will need to make it parallel so that the nut has a solid surface to tighten on to.

I have used this setup for years without any issue whatsoever. Be sure to use new nylock nuts and they will never back out.

I also prefer to use a bolt and tap the mount. I have not used a bolt and nut since the days when engine mounts were hard maple beams that ran back between the first two fuse. formers.

I don't use anything to back them up but do check for tightness every session. That is just part of my pre-flight and I have seldom found a lose bolt.

I use a device sold by Great Planes called Dead-Center that marks the exact center of the engines mounting holes on the mount and then drill using a drill press. I also only use aluminum motor mounts on four strokes.