Checking my centre seal. Made a rig up using 40mm pvc. Have tyre valve and pressure gauge reading from pvc pipe, Using spark plug to block head. Exhaust is a 10mm piece of rubber and a plate over the top.
Before i tried with air i tried with fuel and got ZERO fuel leakage across the centre seal. This was over 18hours.
With air, i pump up to 8psi. Over 3min is slowly drops to to 6.5psi. Over 10 min it drops to 5psi.
When i remove the PVC pipe, the reeds actually trap a fair bit of pressure in the cylinder. I have to poke them open to relieve the pressure.

Question is, is his acceptable ? Previous posts say any leak is bad, but is there an acceptable level ? Im not convinced the centre seal is leaking. May be the exh rubber not being 8psi tight (but tight enough to hold unpressurised fluid) of possible the reeds blocking off and giving the gauge a false read. If the piston is at TDC the air may be slowly creeping past the rings ?
Need to do some more testing over the weekend.
Is it possible to find a leaking side seal without removing flywheel and clutch ?

Cheers Kev
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