Measuring Your Cranks Stroke
Part number:
mycs
Description:
If you really want to know what size engine you have, you must remove a cylinder head.
Take one cyl to tdc and that brings the neighbor cyl to bdc.
Measure with a ruler from the top of the CLEAN piston that's at bdc to the top of the cylinder. Let's say that your measurement is 74mm.
Now bring that CLEAN piston up to tdc and measure to the top of the cylinder again. Let's say that this measurement is 5mm.
You have a 69mm stroke crank.
In the case of our pictured example, the piston protruded OUT of the cylinder by 1mm at tdc and at btc you can see we have 81mm to the top of the cylinder.
We have an 82mm stroke crank.
Now you know the stroke.
Remember that you cleaned the one piston? See the stamp on it that says the size? It may be 90 point something, which makes it a 90.5. Or it may be a 91.93 which makes it a 92.
Ours is a 92
So, the engine shown is a 2180 - it was said to be a 2387. The owner was disappointed.
Take one cyl to tdc and that brings the neighbor cyl to bdc.
Measure with a ruler from the top of the CLEAN piston that's at bdc to the top of the cylinder. Let's say that your measurement is 74mm.
Now bring that CLEAN piston up to tdc and measure to the top of the cylinder again. Let's say that this measurement is 5mm.
You have a 69mm stroke crank.
In the case of our pictured example, the piston protruded OUT of the cylinder by 1mm at tdc and at btc you can see we have 81mm to the top of the cylinder.
We have an 82mm stroke crank.
Now you know the stroke.
Remember that you cleaned the one piston? See the stamp on it that says the size? It may be 90 point something, which makes it a 90.5. Or it may be a 91.93 which makes it a 92.
Ours is a 92
So, the engine shown is a 2180 - it was said to be a 2387. The owner was disappointed.
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