FurryOnTheInside
In Memoriam
I would prefer to tape the gauge to the top tube and perform the compression test as if I was trying to start a stubborn engine. I suppose the main thing though is just trying to be consistent between one test and the next.
When you take the spark plug out, you might as well perform a squish gap measurement. That way if you are getting a low compression reading you'll have an idea why, and what can be done about it.
Spoiler:
Even if you don't want to remove the head (due to the stock gasket being alu and not liking being reused) you can measure the piston-to-head clearance or squish gap.
Fold a length of soft solder into a Y and poke it down the spark plug hole, keeping hold of the bend end obviously. Do this when the piston is close to TDC so that the two ends of the solder find their way to the squish area close to the edges of the cylinder but don't get scraped up the cylinder walls.
Turn the engine over TDC to crush the solder then pull it out and measure in your vernier.
The stock alu gasket is 0.7mm thick. Copper gaskets are available in 0.2mm, 0.4mm and possibly 0.6mm? and twisted Teflon tape which is what I use will crush down to 0.05mm
When you take the spark plug out, you might as well perform a squish gap measurement. That way if you are getting a low compression reading you'll have an idea why, and what can be done about it.
Spoiler:
Even if you don't want to remove the head (due to the stock gasket being alu and not liking being reused) you can measure the piston-to-head clearance or squish gap.
Fold a length of soft solder into a Y and poke it down the spark plug hole, keeping hold of the bend end obviously. Do this when the piston is close to TDC so that the two ends of the solder find their way to the squish area close to the edges of the cylinder but don't get scraped up the cylinder walls.
Turn the engine over TDC to crush the solder then pull it out and measure in your vernier.
The stock alu gasket is 0.7mm thick. Copper gaskets are available in 0.2mm, 0.4mm and possibly 0.6mm? and twisted Teflon tape which is what I use will crush down to 0.05mm
