UK Karting - Notice Board (2-Stroke Karting) : Re: TKM Engine, Barells High or low??

Notice Board (2-Stroke Karting)

Re: TKM Engine, Barells High or low??
Posted by 'bt3962' on 15 Jan 2009 @ 18:04

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bt3962Joined: January 2002
Total Posts: 12
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When describing a barrel as low I would usually be refering to the inlet port timing. The TKM regs. state the inlet port timing as measured with a 0.25 mm feeler guage should not be more than 22 mm before TDC. If set at 22 mm this would be very low. 21.5 would be most normal. Setting the inlet port high is restricted by the corresponding exhaust port timing that must not be less than 28.50 mm (if memory is correct) before TDC. In practice an inlet port timing of 21.35 is about as high as can practical as this is getting very near to the 28.5 mm BTDC setting. So the barrel settings have a range of approx. 0.65 mm or 25 thou. of an inch. Not a lot. However 0.65 mm on a TKM Extreme represents 1.5 ml in head volume which is a lot.
Rule of thumb has a longer (greater) inlet port timing is better for bottom end and a shorter (less) exhaust port timing is better for top end. This is why the TKM rules quote very tight piston skirt dimentions from bottom of the ring groove to bottom of the piston skirt. This is checked by scrutineers.
The next developement was the rotary valve as this enabled the opening timing and the closing timing to be different.

Message Thread:

TKM Engine, Barells High or low?? by 'DanMax66' (14 Jan 2009 @ 21:26)

Re: TKM Engine, Barells High or low?? by 'philharrison' (15 Jan 2009 @ 0:06)

Re: TKM Engine, Barells High or low?? by 'DanMax66' (15 Jan 2009 @ 0:29)

Re: TKM Engine, Barells High or low?? by 'Attack2001' (15 Jan 2009 @ 12:43)

Re: TKM Engine, Barells High or low?? by 'iant' (15 Jan 2009 @ 12:59)

Re: TKM Engine, Barells High or low?? by 'QuickOldTimer' (15 Jan 2009 @ 13:09)

Re: TKM Engine, Barells High or low?? by 'bt3962' << You are here!

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