UK Karting - Notice Board (2-Stroke Karting) : Re: rotax jetting help please

Notice Board (2-Stroke Karting)

Re: rotax jetting help please
Posted by 'jc82' on 09 May 2011 @ 20:20

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jc82Joined: April 2010
Total Posts: 1
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My thoughts below:

hi all ive been slowly getting my head round the rotax carb and i seem to be making little ground . i have a few questions to ask .

as the jets go up i.e 165 to 168 etc does this make the carb leaner ? or is it the opposite way ?

Larger jet = richer.

is jetting software anygood for working ou which needle to use ?

You have a choice of needles (K27 & K98) - only way to work out which one is best for you is to test. Good jetting software will provide options to select either needle type as part of the calculation and will make suggestions for jet size and clip position on that basis. Also - jetting software can determine the optimum plug type for the conditions too. Personally, I find that software is most useful when racing (i.e. when there's not always a lot of time between heats) but you can get by without it as you gain experience.

and what is a good cheap barometer to use to help with jetting.

I found a good one on ebay, circa Ł30 new.

and also any other help is greatly appreciated thanks

When engine is cold/warm (i.e. hasn't reached working temperature) the engine will run a little lean but as it heats up (and therefore requires less fuel) your jetting becomes 'optimal' and any signs of lean running (e.g. popping through exhaust) should disappear - usually after a couple of laps at the most. Also, one carb/engine can have completely different jetting to another, so you need to read what the engine is doing and tune accordingly throughout the day. Whilst you dont want to run it lean, be aware of the above - all too easy to over-jet the carb, and thus lose performance.

Message Thread:

rotax jetting help please by 'mojokart' (09 May 2011 @ 18:56)

Re: rotax jetting help please by 'butkuben11' (09 May 2011 @ 20:00)

Re: rotax jetting help please by 'jc82' << You are here!

Re: rotax jetting help please by 'alanrr' (09 May 2011 @ 22:56)

Re: rotax jetting help please by 'John' (10 May 2011 @ 1:48)

Re: rotax jetting help please by 'Ditch' (10 May 2011 @ 5:01)

this is not an advertising forum by 'NJB' (10 May 2011 @ 8:45)

Re: Neville by 'John' (10 May 2011 @ 9:15)

Re: Neville by 'NJB' (11 May 2011 @ 8:28)

Re: Neville by 'John' (11 May 2011 @ 8:41)

Re: Neville by 'NJB' (11 May 2011 @ 9:19)

Re: Neville by 'John' (11 May 2011 @ 9:33)

Re: Neville by 'NJB' (11 May 2011 @ 10:05)

Re: Neville by 'MattCortes' (11 May 2011 @ 10:19)

NJB..... look at the facts. by 'itpro' (11 May 2011 @ 10:37)

John, that's an anti-virus program. by 'alanrr' (10 May 2011 @ 23:50)

Re: John, that's an anti-virus program. by 'John' (11 May 2011 @ 0:42)

Re: John, that's an anti-virus program. by 'itpro' (11 May 2011 @ 0:50)

Re: John, that's an anti-virus program. by 'KJM' (11 May 2011 @ 13:09)

You'lll never get to 90, you'll get run over.... by 'alanrr' (11 May 2011 @ 13:16)

Re: John, that's an anti-virus program. by 'max27' (11 May 2011 @ 23:50)

I Pad by 'itpro' (17 May 2011 @ 14:55)

Ok John, I've read that but just to iterate.... by 'alanrr' (11 May 2011 @ 13:21)

Re: Ok John, I've read that but just to iterate... by 'John' (11 May 2011 @ 18:29)

In the absence of a sensible answer, Aptare by 'alanrr' (13 May 2011 @ 10:56)

Re: In the absence of a sensible answer, Aptare by 'John' (13 May 2011 @ 11:01)

Re: rotax jetting help please by 'PaulMRotax' (12 May 2011 @ 7:52)

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