Low Budget Chain Guide
by Cameron Carr
The stock one-sided plastic guide on my '03 XR100 is better suited for flipping eggs. I liked the look of the fancy BBR chain guide, but I didn't like the price. There's not much to it, a bit of aluminum and teflon (or UHMW) so I designed and built one. It took about 2 hours in total out of scraps in my shop (cost $0). There are only 2 critical dimensions (other than the mounting holes). The swingarm mount surface to chain edge is 7mm and the width of the chain path is 22mm. The other thickness dimensions can be altered to match the thickness of the teflon used. The left side plate should be 1/4" thick aluminum since this plate creates the strength of the guide. The pics of my prototye are slightly different since the drawings show the final design and the photos were taken at an earlier stage. The geeninsh product I used is called "synsteel" which is a UHMW plastic that contains sintered metal (hey I had it under my workbench). Happy Building. Cam Carr.
For templates click files:
Tech/XR_Chain Guide dwg.pdf
1/4" aluminum plate (LH side plate)
1/8" aluminum plate (RH side plate)
1/2" thick teflon (old cutting board)
1/4" bolts, long enough to go through the finish guide
27mm length small aluminum pipe ( this is a spacer, anything will work - lighter is better)
1. Print off the side plate template and cut them out. Tape them on the aluminum: punch the hole centers with a center punch and mark the outline. Drill the holes 1st then cut out the aluminum plates. Bolt them together and file shape the edges that match. Next, take them apart and file the edges that don't match. You should end up with 2 nicely shaped aluminum plates, a 1/4" thick outer and a thinner inner
2. Clamp the shaped aluminum sideplates to the teflon and drill the holes. Mark the outline, remove the aluminum and cut the teflon to shape. Cut an extra short piece for the bottom. Like the aluminum, bolt the 3 teflon pieces together before final shaping with a file.
3. Cut an 8mm notch in the left side teflon where it bolts to the swingarm. A router is handy, but careful work with a file works fine. To create the 22mm inside gap, the right side teflon can be cut thinner with a bandsaw or hacksaw (use WD40), or a different combination of thicknesses of cutting board (1/4") can be used to get the same approximate dimensions.
4. Polish the LH aluminum plate with an SOS pad, bolt it all together and bolt it on the bike. Don't forget to locktite all the nuts.