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HOW TO: Excelsior motor rebuild Part 2: Reassembly

April 14, 2010

Once the motor parts had been repaired/replaced/rebuilt, it was time to assemble the parts, align and adjust things, then get on the road.

The cast iron pistons and rings were measured and were still fitting the bore.  An advantage to CI pistons is that they don’t wear quickly like aluminum pistons do.  They also are thermally matched to the bore, so they both grow at the same rate as the temperature rises.  This also greatly reduces the chances of pistons seizing.


Lots of holes in the  pistons, especially in the front one.  I thought that maybe they had been modified to be lighter by a previous owner, but the factory photos in the parts manual show all these holes too.



New circlips, and check out the size of the rings!  No oil control rings, this is a constant-loss oiling system.  The oil goes past these rings, then gets burned up and goes out the exhaust valve, then through the muffler.  (the muffler has no rust after all these years…)


Both pistons and barrels installed.  Getting ready to mount in the frame.


IMG_0926 Timing gear in place, with lots of assembly grease.  Notice the new roller cam followers: the inlet cam lobe and followers are visible in this photo.




Motor into frame, then add the Schebler carb, intake valve cages, oil pump and copper lines, timing cover & pushrods, exhaust, primary drive, lots of linkages,set the magneto timing, etc etc etc.

IMG_0176 IMG_0177

 IMG_0182 IMG_0183

On the road for a test drive, with 30 pounds of tools on the rear rack:


The reassembly and test ride were a whirlwind of 2 days and nights.  But I was glad that no major issues came up, and the bike did several hundred miles the following weekend, with just a few nuts and bolts coming a bit loose due to vibration.

7 Comments leave one →
  1. April 14, 2010 1:04 pm

    Nice post! Well composed pictures; elegantly simple text.

    Like the bike itself.

    And laughed out loud at taking 30 lbs of tools on the test run. That would be what, 15% of the bike’s curb weight?

    Looking forward to a future post on what it’s like to ride.


  2. Richard McKenney permalink
    April 14, 2010 3:22 pm

    G’day Pete

    Original pistons? Gudgeon pin turned down for C clips, I’m guessing?
    How much gap do you have on the piston/barrel and what kind of metal did you make the cam follower out of, is it hardened?

    Sorry for so many questions, but I’m doing the same thing, and is this the right place to be posting these questions, or should I duck off some where else?

    We have a mutual friend who has the same Excelsior and I’ve asked for first refusal should he ever sell, but he likes it to much.

    Five star article, inspiring stuff, more please.


    • Pete Young permalink*
      April 14, 2010 3:57 pm

      Hi Richard. The motor was originally made with round section circlips, so I only had to find modern C clips of the correct thickness and diameter to fit. A bag of 100 clips was a few dollars. Let me know if you need some!

      The cam follower is the factory part, a forging. I bought the roller elements, they were drill bushings, made from hardened steel. I’m not sure what material, probably O1 or A2 tool steel. Very hard!

      There is more info in Part 1 of the rebuilding, I’m posting that later today.

      Is that mutual friend Andrew?
      cheers mate

      • Richard McKenney permalink
        April 15, 2010 5:03 am

        G’day Pete

        Your Amazing! make anything, pity you don’t live down the road I need a hand.

        Yes that would be the irrepressible Andrew!

        We drove across Australia from West Oz to Adelaide for the 2005 5th National Veteran Rally in record time, I’m still recovering.

        His nickname was “Turbo” and mine “Sloth”, he like yourself, can make anything it’s a privilege/inspiration to know him, he can fix anything.

        At the 2009 7th National Veteran Rally after a day of Motor Bicycling, you would find broken bikes outside Andrew’s camp awaiting repair for tomorrow, a handy chap.

        I think Occhio Lungo should be on the Discovery Channel, more please.

        Cheers Richard.

  3. July 15, 2013 4:31 pm

    Occhio, I checked my bore-piston gap at .006″ and Charlie Carter who has done several X’s said it’s OK. Compression is very very low so I will just have to run it to see what I have created. Bores were rusty and I just cleaned them up with 180 grit sand paper until the piston would go to the top. It looks strange not having shiny bores, but it might work. Rings will be stock. I’m thinking now I will disassemble the cases too since when I opened my 1913 motor it was dirty inside because of the total loss system. As far as the big end rod bearings I’ll take my chances for now. Too many projects. My valves are just lapped in without any new valves or guides. I want to see if it will run on the old stuff first. Noise is ok with me as long as it’s authentic. Thanks, Paul Venne “slow is fast.”

    • July 22, 2013 10:12 am

      Hello Paul. that sounds like a good plan. I like to put in new rings when I can, even for old pistons and old bores. But the wide rings can be hard to find. There was a website somewhere that was selling wide rings for old car pistons, but I can’t remember the name of it… Best of luck, and be sure to let me know how it all comes together!

  4. May 21, 2014 11:13 pm

    Nice post! Well composed pictures; elegantly simple text.
    Like the bike itself.
    And laughed out loud at taking 30 lbs of tools on the test run.
    Looking forward to a future post on what it’s like to ride.
    RegardsThe content on this publish is really a single of the most beneficial material that I’ve ever are available across. I love your article, I’ll arrive back to verify for new posts.

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