65 Tiger Cub Motorcycle

FRS 106, Michael Littman – Spring 2016

Top End

Chris and Parker

Final Note

We started off the class removing the engine from the bike and disassembling the top end completely, cleaning the parts individually before we started the restoration process.  We then sandblasted the exterior of the head and polished it with an abrasive grit in order to seal against oil stains.  Once we were happy with the condition of the parts, we measured the cylinder to check “squareness”, or whether the dimensions of the combustion chamber were uniform from top to bottom. We then replaced the gaskets, retrofitting them to the correct size in order to eliminate leakage during operation while still maintaining the original appearance of the machine.  We then trued the pushrods, planed the copper gasket on a flat surface with high-grit sandpaper and machinist’s oil, and set to work recutting the valve seats on the interior of the head.  This process involved three separate cuts per valve, each at a different angle.  The most neutral cut was at an angle that would match the taper of the valve itself, and the other two angles allowed us to create a very narrow contact patch between the head and the valves, ensuring optimal flow of the air-fuel mixture into the combustion chamber during operation.

After completing our restoration of the top end, we focused on reassembling the top end, which involves clamping the valve assembly, reinserting the rockers, aligning the camshaft with the crankshaft, fitting the pushrods, setting the valve gap, and finally, setting the spark gap on the spark plug.  With this done, we focused our efforts on the 1962 Triumph, which needed the flywheel replaced.  This ended up serving as a good trial run for the reassembly of our own engine, which went smoothly after we had spent several classes getting the ’62 just right.

We had a great experience and learned a lot over the course of the semester. We just wanted to thank Professor Littman, Glenn, Jon, and the rest of the machine shop for guiding us throughout the rebuild, and the rest of the class for making it such an enjoyable term.

Top End 2016

Chris and Parker

» View the slide show HERE

1965-Triumph-Tiger-Cub_-Top-End Presentation