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Mcculloch flywheel i.d.
#1
theres always a question or two about flywheels for mcculloch.
simplest answer is most of the flywheels both saw and kart will fit most of the motors.
fit doesn't mean work but often they will work even if wrong .
the engine will run just not as well as the engine could run with the correct parts.
The 5 key will face up exactly at the arrow by the magnets, the 'standard' faces slightly off to the left.
You can get over 30 degrees timing with the 5, but either flywheel will get you 26 degrees, which is all you usually want to run anyway.


so identifying which flywheel you have is a useful skill.
this thread is about what you can do to identify the flywheel.
please feel free to post your own methods but if the admin decides the info is wrong it will be deleted.

heres a nicely built jig to determine if you have a 0 or 5 degree flywheel.



               

here is a quote i think goes with these pix. i'll be danged if i remember who wrote it but it's a quote from somebody
"The reference lines on the fixture are established by checking bunches of standard and 5 degree flywheels. You can find small variations from the "norm" for both types but if you go through enough of them then the correct reference line placement becomes obvious based on the sampling. You'll see in the photos that the reference line for each type is the leading edge of the trailing magnet. I chose the leading edge of the trailing magnet as the reference point because it is the critical dimension for determining when the spark will occur if the points are taken out of the system as occurs with Maverick Spark.
There are no "2 degree" flywheels, only standard and 5 degree. The "2" you see on some flywheels does not relate to the magnet position. The magnet position on a Mc10 flywheel is about negative 5 degrees based on the fixture positions. Remember that the flywheel is not the whole story, the key slot position in the crankshaft is an equally important factor in determining the relative position of the magnets to the rod journal on the crank.
Regarding ba1ance, the flywheels are balanced separate from the engines. I've checked plenty of the them and it's rare to find one that is perfect. The older versions are less consistent than the newer version. On the older style flywheels the heavy spot can be anywhere and on the newer style the heavy spot is always in the same place, it lines up with the counter weights on the crank. The amount of error tends to be very small on the newer flywheels compared to the error found on the old version.
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#2
I can say from searching that the casting part numbers on the backside of the flywheel should be treated as you do casting numbers on a crankshaft. Its not viable mcculloch part number found in any of the price guides from 69-82.
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#3
(01-30-2017, 10:50 AM)Mark Loraine Wrote: I can say from searching that the casting part numbers on the backside of the flywheel should be treated as you do casting numbers on a crankshaft. Its not viable mcculloch part number found in any of the price guides from 69-82.

absolutely true the casting number is not a part number. not always but sometimes you'll find a part number on the flywheel. they are always STAMPED IN never cast.
Dave L.
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