COLD Weather Starting your Airhead Motorcycle
©
Copyright, 2011, R. Fleischer
coldstarting.htm-56
When the engine is quite cold it is best to warm it before starting
the engine. In fact, it is better to have the entire bike well above freezing. Not
overly practical in many circumstances. Be cautious,
don't over rev the engine when cold, it is hard on the pistons, camshaft lobes, and many
other places.
MOST engine wear occurs within the first minute or three at
startup. This is true at any
temperature, but very especially when the engine is quite cold.
Many street tires are
very slippery when cold, so be cautious when riding off.
For regular use in relatively cold temperatures I suggest using a
QUALITY thinner than normal multi-grade oil.
Not just for starting
ease, but quicker oiling. I approve
of FULL SYNTHETICS (or my previously recommended partial
synthetic GOLDEN Spectro 4). A thinner grade is
MANDATORY if the weather is QUITE cold. Full synthetics are necessary in constant super-cold
temperatures....few will be riding in temperatures 20 or more
near or below
zero °F.
Here is my
recommendations for an Airhead (and this is good advice for a
Classic K-bike too):
1. Normal temperatures, say from around 40°F to as hot as
it gets anyplace, use a QUALITY 20W50, such as a top-grade
semi-synthetic like Golden Spectro 4; or Spectro's full synthetic
. You really do NOT need the full-synthetic.
2. You could also use a 15W50.
I advise that you avoid starting an airhead if the engine is
colder than about freezing; unless you really need to, and if you
do, best to use a 10W40 or 10W50 oil, the 10W50 preferred if the
oil is going to get fairly hot from high speeds.
For
a Classic K-bike, I can NOT recommend any oils except FULL
synthetic, by Spectro, and by Mobil 1. This is due to the
sprag clutch problems with lesser, dino oils.
Your airhead will start more easily if the starter motor is in top condition, --
I recommend silicone grease be used on the starter Bendix-drive, appropriate oil in the crankcase,
clutch pulled in during starting, an
excellent battery. The battery cables, and the solenoid must be good.
You could take voltage drop measurements to be sure of proper system operation.
ANYthing
marginal, especially in the ignition or valves with too little
clearance, can cause poor starting in cold weather!!
Spark plug gaps can be broadened to .032" (MAX!); ignition
coils checked and cleaned; wires and spark plug caps cleaned and
checked. I suggest 1000 ohm early style caps or 1000 ohm NGK spark
plug caps on the POINTS models.
You can NOT use 1000
ohm caps on the 1981+ electronics models, they MUST have the 5000 ohm
caps. DO NOT USE resistor spark plugs!
Valve and seat condition and valve clearances (especially), compression pressure and
ignition timing must be good. Tight valves or worn top end will make starting difficult...or
impossible.
The engine must spin over relatively fast to get a good start. Kick starting MAY
be especially difficult. The incoming mixture will tend to be less homogenized. A very rich
mixture is needed in cold weather. Spark plugs MUST be clean and dry. If spark plugs are
carboned up, they must be cleaned, and the reason for such carboning, if
excessive, fixed.
The carburetor must be flooded, or in the case of the enrichener-choke-lever airheads, full choke
is used, and
do check that the levers, and enrichener parts, are OK and set correctly.
Carburetor choke levers that do not reach full-on stops (or nearly) may not give full
choking.
***If your Bing CV carburetor equipped bike starts, and then seems to die after maybe 15-30 seconds or so, inspect the carburetor bowl contents, and especially check the bowl gasket that it is intact and good..... and be sure to inspect the little jet in the corner well of the bowl and its side-hole inlet. Failure for fuel to properly flow from the bowl into the well will cause this particular problem, and a clogged or partially clogged jet is commonly found. If the bike does not want to start at all, also check that the corner jet well has fuel in it. Jets can plug-up with crud.
****NOTE!! Cold weather
starting is nearly always
done by using 100% FULL
choke,
AND manipulating the throttle during
cranking. Many manuals, including factory owners
manuals will say not to touch the throttle. In my experience, that is
WRONG!
As soon as the engine is running,
REDUCE the amount of choke as rapidly as you can, yet still maintain smooth
running. Try to keep the rpm between 1200-1500. Do NOT blip the throttle and take the
engine to high rpm, EVER, when starting....the wear will be very
high.....in some situations you can BREAK RINGS with a quite cold
engine.
REPEATING: Some books, including BMW rider's manuals, are NOT correct on starting, cold or not. Some books say to use the choke and not touch the throttle. That sometimes worked for the very early R75/5 with the crude early Bing CV carburetor. It likely will NOT work for YOU.
Note!!....for airheads with the choke lever mounted on the air-cleaner clam-shells (pre-1981), the lever is DOWN for choke ON, and the lever points to the REAR for choke OFF. Some Clymer's manuals are WRONG!, and have it backwards!
Even in the coldest weather, the choke lever should be returnable within two minutes from even the half-way position, to full OFF.
Dual-plugging will, in every case I know about, make starting FAR easier.
Summer gasoline's start with more difficulty, they have less 'non-liquid gas'
dissolved in the liquid.
Revisions:
02/03/2003: add Clymers caution and how cold Wx
starting is done.
04/04/2003: edit for clarity, especially about 1000 and 5000 ohm caps.
09/28/2003: check-over. Moderate clarifications
02/19/2007: minor editing, mostly re-arranging areas and adding emphasis
to existing items.
08/25/2009: minor
06/16/2011: Clarity fixes
© Copyright, 2011, R. Fleischer