I recently purchased a +80 thou (61.00mm) piston from Villiers Services (VS) to be used in an iron barrelled 9E Villiers.
The piston is a Mitaka brand as sold by Grampian Motors in Liverpool and has Teflon pads on both thrust faces and is fitted with thin rings and certainly looks the business .
I generally bore the cylinders on my lathe so the question arose how much clearance?
The usual practice is to bore and hone to the nominal size plus the oversize in this case 61.00mm (2.4016”) to obtain the correct running clearance which in this case works out to be 0.04mm (0.0016”) a bit tight for my liking, I’m more used to 4 to 5 thou clearances with Villiers pistons.
I then contacted VS and will quote the reply verbatim “ Hi, 4 thou is fine. The alloy is low expansion.Steve”.
Not being entirely happy I contacted Jim at Grampian Motors who was very helpful and stated that they had no experience with Villiers cylinders, but they ran 0.003” clearance on Lambretta cylinders without any problems.
He then went on to say that they organised the manufacture of the pistons to VS specification in a low expansion alloy.
Can anyone tell me of their experience or offers any advice?
The piston is a Mitaka brand as sold by Grampian Motors in Liverpool and has Teflon pads on both thrust faces and is fitted with thin rings and certainly looks the business .
I generally bore the cylinders on my lathe so the question arose how much clearance?
The usual practice is to bore and hone to the nominal size plus the oversize in this case 61.00mm (2.4016”) to obtain the correct running clearance which in this case works out to be 0.04mm (0.0016”) a bit tight for my liking, I’m more used to 4 to 5 thou clearances with Villiers pistons.
I then contacted VS and will quote the reply verbatim “ Hi, 4 thou is fine. The alloy is low expansion.Steve”.
Not being entirely happy I contacted Jim at Grampian Motors who was very helpful and stated that they had no experience with Villiers cylinders, but they ran 0.003” clearance on Lambretta cylinders without any problems.
He then went on to say that they organised the manufacture of the pistons to VS specification in a low expansion alloy.
Can anyone tell me of their experience or offers any advice?
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