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caster oil

I've just been reading the manual for a 1903 Minerva motorcycle engine. The instructions for starting when cold include injecting a spoonful of paraffin into the cylinder head (through a specially provided valve) in order to free up the piston rings which might otherwise have been stuck by congealed oil.

I wonder how quicklythat idea was dropped? I imagine the oil was probably castor based, so is paraffin the magic solvent for gummed-up OHC Nortons using Castrol R?

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Having a 1905 Minerva, I can confirm that I no longer have to add paraffin to thin the oil. Oil in these days, normally mineral monograde, was thick and became very viscous in cold weather. In winter, there was almost no chance of turning it over fast enough to start it with oil turned to treacle, hence the need to inject some petrol or paraffin into the head or cylinder to get it to turn over.

Modern SAE 40 or 50 has solved that particular problem.

So nothing to do with Castrol R and piston rings.

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Very interesting, Gordon - good to hear from another owner - going off Nortons completely now though! The actual wording in my book is "to clean congealed oil from the piston rings".

But before I go - this is the Minerva engine QuadrantI ride - have I seen you on the Pioneer Run? Banbury was too much effort last year - too hilly for my lack of horses. I'm currently trying some adjustments to recover some power.

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Staying off topic (shame...). Haven't been on either Banbury or Pioneer runs, though do go on the Bamburgh and Scottish runs on the Douglas. The Minerva is a Chater-Lea framed device, recently put into running order.

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