Topic: Motor refinishing question

[Johnny5]

After sorting through the engine with only 4k miles on it, I decided it's not needed to crack open since it doesn't have any leaks and has good compression. I do want to dress it up the engine a bit this winter when I pull it out to get the frame powdercoated.

Question on bead blasting, can it be done to strip the paint from the fins while the engine is still together? I don't want to hurt anything but I really like the plain metal look of old fins.

[calj737]

Highly unadvisable to bead blast an assembled motor. The media will find its way into oil galleys and bearing surfaces. This will drastically shorten the lifespan of your motor. Some have sofa blasted their motors, but that does necessitate flushing the entire motor well as soda/oil cause congealing of the oil.

Best to simply use wire brushes and elbow grease and solvents to strip the motor. I like stainless steel brushes to cut through the oxidation. It also doesn't scratch so heavily against raw aluminum. You can follow that up with ScotchBrite pads for a more brushed finish.

[Johnny5]

Ah, I would have thought stainless steel brushes would be too aggressive. Nice suggestion. Thanks man.

Highly unadvisable to bead blast an assembled motor. The media will find its way into oil galleys and bearing surfaces. This will drastically shorten the lifespan of your motor. Some have sofa blasted their motors, but that does necessitate flushing the entire motor well as soda/oil cause congealing of the oil.

Best to simply use wire brushes and elbow grease and solvents to strip the motor. I like stainless steel brushes to cut through the oxidation. It also doesn't scratch so heavily against raw aluminum. You can follow that up with ScotchBrite pads for a more brushed finish.

[calj737]

Stainless brushes are used when welding aluminum for the very purpose of scuffing away the oxidation. Much softer than carbon brushes and brass.

[SOHC4 Cafe Racer Fan]

I wonder if the motor could be soda or vapor blasted (assembled).

[calj737]

I wonder if the motor could be soda or vapor blasted (assembled).

Yes to soda, but requires heavy flushing afterwards. No, to vapor blast. Vapor blasting is done in a cabinet and I doubt seriously anyone around has a cabinet large enough to do an entire motor without significant disassembly.