UK Karting - Notice Board (2-Stroke Karting) : Re: Castor oil in rotax??

Notice Board (2-Stroke Karting)

Re: Castor oil in rotax??
Posted by 'SimonS' on 15 Apr 2009 @ 19:24

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SimonSJoined: December 2004
Total Posts: 4
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Your tall tale detector should be bleeping at full volume.

Castor oil has a very high film strength, so is used to cushion the running in process where you are mating bore and ring. Essentially you are scraping the barrel, removing very thin layers of material on the high spots of the ring and barrel. However you do not want to have a bare metal to metal contact, so the high film strength of castor helps to heal the skin of oil and protect the surface.

However, with the very hard, very smooth surface of a chromed or Nikasil barrel, the running in process doesn't or shouldn't be scraping the surface (because it can scrape all the way through) so the higher lubrication of synthetic is often recommended.

But, a lot of racing oils are now semi-synthetic, that is they contain castor for the film strength and synthetics for lubrication. Castrol 747 for example is a semi-synthetic which reputedly can be used down to 2%, as low as many fully synthetic oils.

The well known problems of pure castor are that it leaves a residue that can produce a soft varnish in carburettors and a hard glaze varnish in the bore and on the rings. It is possible to gum the rings up so they don't move if you run the engine on castor for an extended time.

But using the varnish to reduce your capacity sounds very iffy, and while technically the black of carbon may transmit heat more evenly, I have my doubts if it is particularly useful since in an engine you are normally trying to keep the metal cool, not heat it up, and shiny is better at that.

Message Thread:

Castor oil in rotax?? by 'TheROTAXkidakaTKMkid' (14 Apr 2009 @ 14:40)

Re: Castor oil in rotax?? by 'gettingquicker' (14 Apr 2009 @ 17:17)

Re: Castor oil in rotax?? by 'TheROTAXkidakaTKMkid' (14 Apr 2009 @ 19:01)

Re: Castor oil in rotax?? by 'gettingquicker' (14 Apr 2009 @ 19:40)

Re: Castor oil in rotax?? by 'dave56' (14 Apr 2009 @ 20:46)

Re: Castor oil in rotax?? by 'DBaldwin' (14 Apr 2009 @ 20:54)

Re: Castor oil in rotax?? by 'intrepidcorby' (14 Apr 2009 @ 21:31)

Re: Castor oil in rotax?? by 'gettingquicker' (14 Apr 2009 @ 21:42)

Re: Castor oil in rotax?? by 'dave56' (14 Apr 2009 @ 21:45)

Re: Castor oil in rotax?? by 'TheROTAXkidakaTKMkid' (14 Apr 2009 @ 21:59)

Re: Castor oil in rotax?? by 'dave56' (14 Apr 2009 @ 22:05)

Re: Castor oil in rotax?? by 'gettingquicker' (14 Apr 2009 @ 22:13)

Re: Castor oil in rotax?? by 'gettingquicker' (14 Apr 2009 @ 22:15)

Re: Castor oil in rotax?? by 'razh54' (14 Apr 2009 @ 23:11)

Re: Dave56 - Wrong! by 'John' (14 Apr 2009 @ 23:48)

Re: Dave56 - Wrong! by 'alanrr' (15 Apr 2009 @ 10:37)

Re: Dave56 - Wrong! by 'TheROTAXkidakaTKMkid' (15 Apr 2009 @ 12:47)

Re: Castor oil in rotax?? by 'SimonS' << You are here!

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