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Motorcycle Engine Protection



Introduction

Ever since I started riding off-road more seriously I noticed the plastic engine protection the bike is fitted with originally is insifficient. The original is fabricated from a tough plastic which is perfectly suited for small debris typically encountered on pavel roads. I found however that the occasional rock or tree stump leaves the protector riddled with cracks.





fig 1: Top- and bottom view of the original protection plate.

The large unprotected are on the bottom of the engine indicates the designing engineer had esthetics in mind rather than rugged off-road performance.
In my opinion the available aftermarket products combine a high sales price with unattractive design so for some years I settled on a 30 euro conversion of an original Africa Twin part. Functional but a bit misplaced on the Transalp I kept my eyes and ears open for alternatives. In 2013 the project took a new turn after a discussion on the Dutch Transalp message boards made me realise I wasn't the only one looking for an alternative and a small series production opens the door to outsourcing of some of the fabrication.

The Prototype

I took some rough measurements of the motorcycel and the original part and cut out a piece of 3mm thick aluminium sheet. After bending the plate to match the curves of the frame tubes and manufacturing a set of rubber-lines brackets I started fine-tuning the design. I was looking for full protection of the bottom and front of the engine but a slightly more modern look.





fig 2: Progress on the prototype.

I wanted to be able to lift and support the bike directly on the engine protection, rather than having to remove it. The main reason for this feature is that flat tires are more common when riding off the paved roads and the less work you need to fix a tire the better your travels are. The aluminium sheet is thick enough to support the full weight of the vehicle, but the mounting brackets needed some work. I found some heavy-duty rubber-lined tube clamps and made my own brackets in stainless steel.

Accessibility of the mounting bolts was poor, so the second iteration bracket was designed with an offset that allows easier acces with tooling.


fig 3: Prototype mounting brackets.



fig 4: Finished prototype.


Testing


fig 5: A tire change in Central Asia.


The prototype was put to the test around town and on small dirt roads in th area. After verifying that the protection plate does not interfere with any of the controls and is not a source of any unwanted vibrations, I started an endurance test.

Over the course of two years I put the engine protection to the test in all the possible environments and conditions Europe and Central Asia have to offer, crossing over 30 countries and 30.000+ kilometers.

Production

Satisfied with the overall performance I went back to the drawing board and transferred the prototype to CAD. The final product is made from 4mm thick aluminium sheet, laser cut by CNC, bent manually TIG welded. AS my time is limited I optimized the design for manufacturing.


I can now assemble the final product without templates or jigs to ensure dimensional accuracy. Simply following a specific order of operations ensures the part fits accurately.





fig 6: Brackets and weld-seams of the final product.





fig 7: Finished product.





fig 8: Finished product fitted to a XL650V.

Pedro Mota Riding Around the World

Pedro has been travelling around the world for a couple of years now and contacted me while he was rebuilding his Transalp in New Zealand. I made him a sump guard which is now keeping his engine damage free in South America! Pedro has a youtube channel you can follow HERE.