UK Karting - Notice Board (2-Stroke Karting) : Re: so i guess its not??

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Re: so i guess its not??
Posted by 'SimonS' on 25 Feb 2009 @ 17:21

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SimonSJoined: December 2004
Total Posts: 4
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There is something called chordal action that affects chains, and I guess it loosely translates as 'whip'.

Essentially if you have a constant load on a chain it will go round the sprocket more efficiently at some revs rather than others.

However, with a kart you are varying the power and the revs so much that the chordal action is less predictable. About the best you can do is to use a datalogger to see what revs you spend most time at, then use the tables to look up the right distance between the centres for that combination of power (see your dyno curve) and revs and then see if the 'best number of links' for that distance of centres is an even number. (chains usualy only come in even link lengths. Use the chain length nearest to the 'right length' and adjust the distance between the centres by moving the engine.

In a worst condition chordal action can increase the resistance due to chain/sprocket interaction by 3%, but you have to see that this is only one part of the overall resistance and the improvement only applies for a small part of the revs that you are using.

The important thing is not to make the chain too tight (about 1 cm of play), this allows the system to 'adjust' itself by the right chordal action and to mqke the distance between the axle and the crankshaft at least equal to or greater than the diameter of the rear sprocket or 20 links whichever is the larger.

With most karts you really dont have an option, though I guess you could move an engine right back on the mounting bars (but then you couldn't get at the carb etc during the race)

Message Thread:

chain lengths ?? by 'buzzinrussell' (23 Feb 2009 @ 15:57)

Re: chain lengths ?? by 'yeoy' (23 Feb 2009 @ 16:43)

Re: chain lengths ?? WHAT DIFFERENCE? by 'cosgrove78' (23 Feb 2009 @ 17:06)

Re: chain lengths ?? WHAT DIFFERENCE? by 'John' (23 Feb 2009 @ 17:16)

Re: chain lengths ?? WHAT DIFFERENCE? by 'cosgrove78' (23 Feb 2009 @ 17:20)

Re: chain lengths ?? WHAT DIFFERENCE? by 'richydehav' (23 Feb 2009 @ 17:35)

Re: chain lengths ?? WHAT DIFFERENCE? by 'itpro' (23 Feb 2009 @ 17:36)

Ian to start a discuison by 'stecrmh51' (23 Feb 2009 @ 17:41)

Re: Ian to start a discuison by 'buzzinrussell' (23 Feb 2009 @ 18:26)

Re: Ian to start a discuison by 'MJC' (23 Feb 2009 @ 18:55)

Re: Ian to start a discuison by '5kyle8' (23 Feb 2009 @ 22:29)

Re: Ian to start a discuison by 'itpro' (24 Feb 2009 @ 1:28)

Re: Ian to start a discuison by 'itpro' (24 Feb 2009 @ 1:36)

Re: Ian to start a discuison by 'Volts' (24 Feb 2009 @ 7:24)

Re: Ian to start a discuison by 'itpro' (24 Feb 2009 @ 11:26)

Re: chain lengths ?? by 'SimonS' (23 Feb 2009 @ 22:58)

so i guess its not?? by 'cosgrove78' (24 Feb 2009 @ 12:00)

Re: so i guess its not?? by 'SimonS' << You are here!

Re: chain lengths ?? by 'Daddyfix' (25 Feb 2009 @ 21:46)

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