Installing the Pistons and Cylinders

Be sure to orient each piston properly, as you prepare to install each one onto a connecting rod. Carefully examine the piston-top. If your pistons are flat-topped, refer to the service manual for directions in orientation. Also, if you are reinstalling your stock (or other) pistons, be sure you get each piston back in the same cylinder it came from.

If you are installing high compression pistons, you will see that the dome is not centered. It is somewhat shifted to one side. The piston side with the most dome should be oriented away from the engine-center--at least it did in the case of my Nemesis pistons. Check with your supplier to get the orientation correct for your pistons, but is probably the same as the Nemesis. See photo below.

Install the right-side wrist-pin retainer into the piston.

Tip: There is a notch in the piston to help you get a small tool in to insert the retainer. Rotate the retainer so that one of the ends is near this notch; it may be easier to get the retainer in.

Safety Warning: It will take significant force to insert the retainer. Sometimes they flip out with great force. Protect your eyes.

Tip: I recommend you always replace the retainers with new ones. It is very cheap insurance against a warped or weakened retainer. The Parts and Tools article in this series has the part numbers.

If you haven’t done this already, place some rags into the crankcase cylinder holes and against the cylinder studs. This precaution is to prevent loosing the other wrist-pin retainer into the crankcase, and to protect the piston. See photo below.

Lube the wrist-pin, the connecting rod bearing, and the wrist-pin bearings of the piston with assembly lube. Then position the piston over the connecting rod. The wrist-pin retainer should be facing to the bike's right-side.

Now slide the wrist-pin through the piston and connecting rod.

Next, install the left-side wrist-pin retainer. Be careful not to scratch the piston skirt. See photo below.

Tip: There is a notch in the piston to help you get a small tool in to insert the retainer. Rotate the retainer so that one of the ends is near this notch; it may be easier to get the retainer in.

Safety Warning: It will take significant force to insert the retainer. Sometimes they flip out with great force. Protect your eyes.

Tip: I recommend you always replace the retainers with new ones. It is very cheap insurance against a warped or weakened retainer. The Parts and Tools article in this series has the part numbers.

Next, remove the rags from around connecting rod for the cylinder you’re going to install.

Insert alignment dowels into the dowel holes in the crankcases, at the base of the cylinder studs. Only do this for the cylinder you're working on.

Tip: Be very careful not to drop a dowel into the engine!

Install a cylinder base gasket. Make certain it is oriented so that all the holes line up.

Tip: Insert wooden blocks under the piston, across the cylinder base to support the piston. I used two, 7 inch lengths of 1"x2" scraps, placed cross-wise. This helped keep the piston from sinking as I worked the cylinder onto it.

Check the chamfer along bottom edge of cylinder sleeve. If it's even a little bit rough, oil-sand it to smooth the inner edge of the sleeve bottom. Finish this process with 400 grit paper.

Clean and re-oil the sleeve bottom after sanding, as needed. Next, check that the piston rings are still distributed properly, then slide the cylinder down over the studs and let it rest squarely on the piston's top ring.

Take picts.

Wiggle the cylinder slightly and carefully over the top ring. Do this at a point furthest from the ring’s gap.

Now, use your fingers or a plastic tool (see the Tip below to see what I made) to compress the ring while gently wriggling the cylinder over the ring. This takes a lot of finger pressure, but you must be careful not to damage any ring. It should not take a lot of downward pressure on the cylinder.

Take your time--even an hour for each ring, if you need to. Just don't scratch, or otherwise damage, a ring. If you do, you'll need to get replacements, and start all over--which is still better than installing damaged rings that may quickly ruin your cylinder and piston.

Tip: I found a couple of plastic, plumbing, faucet wing-nuts in my tool box. I filed a flat onto one of the wings of each nut. I used them sort of like sewing thimbles. They worked pretty well in allowing me to save my fingers, and put more pressure into the ring, as I worked it in, around the cylinder sleeve. See photo below.

Repeat for the other rings. Proceed carefully--especially the thin ones and the oil expander ring (squiggly one).

Important Warning: If a ring gets bent at all or scratched, you must get new rings and start over.

Once all the rings are inside the cylinder, remove the wooden blocks from under the piston. Then push the cylinder all the way down, and over the alignment dowels.

Repeat this entire process for the other piston, rings, and cylinder.

Also see the How to install Hi-Compression pistons in a Roadstar article in this website for more information on installing pistons.

To access related articles, refer back to the Complete Engine Tear Down, Orientation article in this series to see which additional articles best address your situation.

Questions should be asked in our forum (Use discuss link below). The forum is very active and you stand a good chance of getting your questions answered there. If you would like to leave feedback for the author, or have additional information you think will benefit others, please use the comment section at the bottom of this page.

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DISCLAIMER: This information and procedure is provided as a courtesy and is for informational purposes only.  Neither the publishers nor the authors accept any responsibility for the accuracy, applicability, or suitability of this procedure.  You assume all risks associated with the use of this information.  NEITHER THE PUBLISHERs NOR THE AUTHORs SHALL IN ANY EVENT BE LIABLE FOR ANY DIRECT, INDIRECT, PUNITIVE, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, OF ANY NATURE ARISING OUT OF OR IN ANY WAY CONNECTED WITH THE USE OR MISUSE OF THIS INFORMATION OR LACK OF INFORMATION.  Any type of modification or service work on your motorcycle should always be performed by a professional mechanic. If performed incorrectly, this procedure may endanger the safety of you and others on your motorcycle and possibly invalidate your manufacturer’s warranty.

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