Piston Rings: Perfect Circle
71148, Hastings 278. Oversize available through 0.050 on
Gas cap: NAPA 7031020 fits but
does not have the oil measuring cup attached as does the
original. Use only the NAPA cap, do not substitute with another
Kick starter return spring:
Garner 1112270135-MR. A turn must be removed, ends torched to
soften and hooks formed at ends. These springs do not fit all
the kick starters as some of them have a larger diameter
bushing extending from the rear of the starter.
Carburetor: The 1948 Martin 40
outboard engines used a Carter carburetor which can be modified
to work with the Dynacycle engine. Venturi size is correct
(23/32), fuel mixture adjustment comes out the bottom.
Needle bearing MUST be installed
by pressing from the imprint side. Apply grease to the outer
shell before installing.
I have several unfinished pistons
available. OD requires machining to match your overbore, ring
groove cut and ring anti-rotation pin installed. Wrist pin bore
already machined. New wrist pin and clips are available for an
additional $4.50. These are PREMIUM quality, cost me a kings'
ransom, but I have more than I will ever need $35 each. Also a
few finished stock bore and 0.010 oversize $75 each.
I urge Dynacycle owners to use
Amsoil Sabre Pro oil, 40:1 ratio. It burns clean, sparkplug
The intake reed is prone to
pitting and cracking which seriously affects starting and
performance. I have the 12 mil spring steel material available
at no charge or will make the reed to $8. There are two versions
available; one with a single attachment screw, the later engines
using two screws. If you want me to make a replacement, let me
know which version you have.
Air cleaner: Walbro CAA-4H. This
is a nylon-cased filter that fits and functions very well.
Replacement element (foam rubber): Walbro 125-15.
If your lower connecting rod
needles are pitted (28 pieces), try cracking open a B-1612
needle bearing for replacements. The nipples at the ends of
these needles may require moderate buffing to remove sharp
edges, if present.
Muffler shell can be replicated
by using 2-1/4 exhaust pipe, ~18 length with the one end
belled down to ~1-1/4 diameter hole (production units were
inconsistent. I have measured everything from 1-1/8 to 1-7/8).
Sixteen guage is preferred, however it is difficult to locate.
Your muffler shop has the equipment to do this. Muffler insert:
Patriot H2971. Some of these inserts have a cap at the far end
which will require removal prior to slipping into the muffler
shell. I have drawings of the two pieces that attach to the
exhaust pipe (nose cone and nut). Email me for copies at
Early production Dynacycles did
not have a fuel filter installed. It is imperative that one be
placed in the fuel line to keep debris out of the carburetor.
See Service Bulletins.
The clip securing the kick
starter to its shaft is prone to coming off. Consider drilling
and tapping a 1/4-20 hole in the end of the shaft; install a
bolt and large diameter washer (1 minimum).
If your engine is not
equipped with the lighting feature, consider replacing the
ignition points with a solid-state module. Timing position is
the same as with the point configuration. Suggested installation
pictures available upon request.
After sixty-one years of riding
Dynacycle, I have learned the wisdom of always carrying a spare
spark plug and removal tool. You can't drive a single cylinder
engine with a fouled plug!
Dynacycle issued a Service
Bulletin and provided a part for attachment to the bottom of the
kick stand. The stock kick stand has an extremely small
footprint, whichh can penetrate into warm asphalt or any soft
ground causing the machine to tip. This, in turn, may cause
the carburetor float to lose control allowing the fuel tank to
drain. Upgrade part consisted of a 1 X 2-1/4 oval plate with a
5/16 rod welded to it. After removal of the tang at the bottom
of the stock kick stand, the rod was slipped into the bottom and
welded into place.