Another part to my 2008 Triumph Bonneville that I have decided to modify after my accident is the front sprocket cover. In my case it is a black powder coated cast aluminum part from Triumph.

I have been collecting ideas of various designs and modifications I’ve seen posted online. I decided that I still wanted the protection of a full cover, but to add some personalized touches.

Based upon the Joker Machine headlight ears, I have been drilling holes in various parts of the bike (chain guard, shift lever). I decided upon this same basic direction for the sprocket cover as well.

First I laid out my design in pencil on the cover. After several layouts, I decided on 4 holes in a line across the centerline of the cover.


Final 4 hole layout on my front sprocket cover

Next, I center punched each hole and drilled small pilot holes to guide me with the larger holes to follow.


Pilot holes drilled, ready for drilling to larger sizes using a drill press.

After attempting to drill out a larger hole using my drill press, I decided that using a hand drill would be easier and safer, so I switched to clamping the cover in a vice and using the stepped bit in my Makita hand drill.


Larger holes drilled out using a hand drill and stepped drill bit.

I used the stepped bit to also countersink the holes on the outside and inside.


Holes de-burred and countersunk inside and out.

I used a cut off tool and angle grinder with various metal cutting, sanding and polishing wheels to remove the inside aluminum bosses and clean up the holes.


Inside aluminum bosses ground and polished to a smooth inside finish.

I then used metal scotch pads to clean and smooth out the inside and outside, prepping the metal for painting.


Inside of my modified front sprocket cover


Outside of my modified front sprocket cover.

You can see that I ended up drilling two smaller holes at the front and back and two larger holes in the middle. It just looked right to me.

March 8-9, 2014 Updates

This past weekend I started applying final coatings to the sprocket cover. I am using black Plasti Dip by Performix, which I purchased from Home Depot.


Inside of front sprocket cover with a coat of black Plasti Dip


Plasti Dip spray can – by Performix


Now that is a really nice looking finish for a hand held $6 spray can!