The Triumph Tiger Cub gets a new piston!

If you have been following the blog, you know that I have been working on restoring a Triumph Tiger Cub, slowly but its coming together. Last week I went over to Frankie's house to pick up the engine to attempt to finish it by myself.

Frankie told me to support the connecting rod with some wood shims to prevent the rod from banging around. There is a little play in the rod, but I believe within serviceable limits.

Frankie gave me the tip of using a socket that is slightly smaller than the grudgeon pin to drive out the pin only far enough to clear the connecting rod. Then simply slipping the new piston into the connecting rod. Its that simple!

A few short raps of a ball peen hammer... 

Voila! The old piston 

Inserting the new piston was as simple as removing the old. Using a chunk of wood for stability I was able to use the same ball peen hammer to drive the new pin into the connecting rod. 

This piston is bored over 0.04" and appears to be a higher compression piston in comparison to the old, tired piston.

Last step is to replace the clips. One goes on each side of the piston and they can be a real bear to position. I found myself struggling to get both sides in before having it ricochet across the room. 

It definitely was a game of hide and seek trying to find the clips after they would shoot off, but after some struggling both sides seated nicely.

Fast forward to the next day, I got up early to start working again. I polished up these valve covers right away.

First blood goes to the triumph.

While trying to tighten a bolt my hand slipped jamming against a sprocket tooth.

The new clutch plates were a pain to get into the basket. Simply put, they would not fit. I had to take them all to the grinding wheel and slowly take off 1/32" to 1/16" all the way around the circumference just to get them to fit.

Above you can see the bare metal that I used an awl to transfer from the old plate so that these "new" plates would fit. This project is turning into quite the headache, but just have to keep powering through it.

When all was said and done, I had to leave the engine in this state. Anything look out of place? The primary chain is far too loose and will strike the engine casing if closed up in this state. After some research, I found that the Tiger cub was designed with a chain tensioner in mind, but never implemented! Hence why this chain is so loose. Drat! I also learned that these chains came in two different styles. Early Tiger cubs were fitted with chains that would stretch over time, but the later models were fitted with "pre-stretched" chains that were found to last a lot longer. One step forward, two steps back. 

Stay tuned!