CA77 Piston / Rings Installation - How to WITHOUT ring compr

MotoX109 · Post by **MotoX109** » Tue Jan 14, 2014 2:41 pm

Hi everyone. I recently installed new pistons and rings on my CA77. The CA77 motor, unlike the CB77, has each piston moving up and down at the same time. With one person, trying to compress both piston rings and push down the cylinder is nearly impossible. After some wasted time and an abundance of frustration, I wanted to pass along an easy way to get it done. I'm sure many guys/girls have done it this way in the past, but I didn't find any posts.

In short - install one piston to the connecting rod and with the cylinder off of the bike, install the other piston into the bottom of the cylinder (up to the wrist pin). That piston will hold in the cylinder as you carefully work the connected piston into the other cylinder. I compressed each ring one by one with my hands and carefully with a flat head screwdriver. Once you have the connected piston into the cylinder, the other side will now be easy to line up the top of the connecting rod and push the wrist pin through (Don't forget to have your circlip ALREADY INSTALLED on the inner side of this piston.) Install the final circlip on the outside and you are done.

Long Form (Sorry I didn't take pictures while I was doing this....I will on the next CA77)

1. First things first is obviously to install the rings on each piston (always with manufacturers marks facing up). *FYI - The ring that is silver on the outer edge is the TOP RING*
2. Choose which side piston will be installed to the connecting rod and remember that the mark/arrow stamped on the top of the piston goes towards the front of the motor. Attach that piston to the connecting rod with rings already installed. One piston is now fully attached to a connecting rod, with both circlips installed.
3. Now you have the cylinder still off of the bike and one piston unattached to the final connecting rod. Install one circlip on the inner side of the remaining piston. For example, if the left side piston is remaining, install the circlip on the right side.
4. Compress each ring individually and push into the bottom of the cylinder...CAREFULLY using your fingers and a flat head screwdriver. (Be sure the gaps of each ring are oriented 120 degrees apart). Push the piston into this cylinder until you get to the top of the wrist pin hole.
5. With one piston sticking out of the bottom of one cylinder, lower the cylinder onto the bike. Now, individually compress each ring on the connected piston in the same manner as before.
6. After the connected piston slides into the cylinder, the final step is to attach the wrist pin on the opposite side and then the final circlip.

I hope this helps someone who might not have 3 people available and/or proper ring compressors. Cheers - Bobby

sixtiescycle · Post by **sixtiescycle** » Tue Jan 14, 2014 3:56 pm

Bobby, you should have posted the question to the forum and someone may have told you to use two hose clamps as ring compressors, one on each piston. Works like a champ.

MotoX109 · Post by **MotoX109** » Tue Jan 14, 2014 7:10 pm

Haha I went for the scenic route

Dgormley · Post by **Dgormley** » Thu Jan 16, 2014 11:01 pm

Bobby, I've used that same technique on old British twins, works slick.................D

jensey · Post by **jensey** » Sat Jan 18, 2014 3:03 am

Hi,

I put the pistons plus rings into the cylinder without attaching them to the conrods, easier and more control. I already put the piston pin clips in their grooves (on both pistons one, at the inner side). Then I slide the cylinder onto the studs, and adjust the height with some pieces of wood. I align the crank so that both conrods are aligned with the piston pin holes, and put both pins in. After that I install the piston pin clips and push the cylinder down after removing the wooden blocks.

This way you will always know that the piston rings are assembled in the right way.

Jensen

btw, this only works on twins, on fours I use a different procedure.