UK Karting - Notice Board (2-Stroke Karting) : Re: rotax power valve help

Notice Board (2-Stroke Karting)

Re: rotax power valve help
Posted by 'KenE' on 09 Feb 2011 @ 20:26

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KenEJoined: February 2006
Total Posts: 1
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As said above there is a very good article on maintaining the power valve on this site under "Karts/Karting - Technical" with pictures.

Once reassembled there are two critical set-up details apart from it being clean and working.
Firstly, the 'blade length'. This is measured from the centre of the blade end (middle of the concave bit) to the tip of the black plastic nut on the outside of the valve assembly. You change the length by turning the blade either clockwise (shorter) or anti-clockwise (longer) relative to the black plastic cap. Realistically you will need a digital micrometer to do this properly - a good starting length would be 75.0 mm but a change of 0.1 mm can make a huge difference to performance depending on which track you race at.

The blade should be reasonbly stiff to turn but definately not loose. Most people achieve this by putting a tiny dab of threadlock on the thread of the blade stud before screwing it into the black cap during reassembly.
Secondly, after blade length adjustment, the blade itself must be exactly in line with the two mounting holes on the valve body. This is so that the blade does not hit the sides of the slot on the engine when remounted. You can check this by placing a ruler on the flat side of the blade and looking at the holes.

If you want to make these maintenance jobs quick and easy it would be worth buying 2 tools: main spring fitting tool (Ł10-15) and a digital micrometer (Ł30) then all you need is brake cleaner and a little bit of help from your friends at the track!

Message Thread:

rotax power valve help by 'Simon43' (07 Feb 2011 @ 8:39)

Re: rotax power valve help by 'John' (07 Feb 2011 @ 9:24)

Re: rotax power valve help by 'Les' (07 Feb 2011 @ 21:48)

Re: rotax power valve help by 'John' (07 Feb 2011 @ 23:50)

Re: rotax power valve help by 'raceinstructor' (08 Feb 2011 @ 17:41)

Re: rotax power valve help by 'John' (08 Feb 2011 @ 18:13)

Re: rotax power valve help by 'fatkartman' (08 Feb 2011 @ 21:21)

Re: rotax power valve help by 'raceinstructor' (08 Feb 2011 @ 22:37)

Re: rotax power valve help by 'fatkartman' (09 Feb 2011 @ 10:14)

Re: rotax power valve help by 'KenE' << You are here!

Re: rotax power valve help by 'Les' (09 Feb 2011 @ 23:26)

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