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More on oil pumps?

Submitted by paul_webb on Mon, 06/01/2014
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Heavy Twins

I have a number of spare Nortonoil pumps which I assume are all for heavy twins? but when you compare the hole ports some have only holes, some have slots and holes and some have a hole with long and short slots. what models are they for? whatis the definitative answer? I have at some time seen aphotograph showing all the variants togetherand what they are but I have drawn a blank in finding that image. Can any member enlighten me.

Regards, Paul.

Submitted by paul_webb on Sun, 09/02/2014

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Would there be an issue fitting the pump as shown in Fig 7. which has the elongated feed port but with a 3 start worm and gear for use on low pressure system?

Regards, Paul.

Submitted by phil_hannam on Sun, 09/02/2014

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Fig 7 shows the higher capacity pump as used on the twins from the advent of the 650 engines. At first it was used in all the various size of engines with a three start worm but after engine 116372 this changed to a six start for all motors with bleed holes in their conrods.

This pump was generally (but not always) stamped with a letter 'S' to identify it from the outside.

The elongated hole just allows an easier route for the oil to get through the pump and can be safely used on the 500cc and 600cc engines. If anything it is a better pump to use as the increased feed and return flows give both the big ends and the rockers a better feed of oil.

 


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