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Pilot Screw Setting

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  • Pilot Screw Setting

    I'm going through the carbs and for the first time I've removed the brass plugs covering the pilot fuel screws. So this is the first time they've seen daylight in 21 years
    The carbs 102 guide recommends 1.75 turns of the screw. I have the haynes manual which has several different settings depending on country and engine.
    For the USA they offer no setting - it's sealed

    for a 750f in Canada, Austria and Switzerland they say it should have 3 turns. For other European countries they have 2 turns on the outer carbs and 1.5 on the inner carbs.

    The original factory setting was 2.5 turns on the outer carbs, 1 turn on carb 3 and 1.5 turns on carb 2. To me this seems like the carbs were originally set up by monkeys! The one carb with one turn out has to be a mistake.

    I would like to set it like the Canadians have it 3 turns on all carbs. Apparently 3 turns is the maximum rich. Maybe 2.25 is OK? I have a nice
    wileyco aftermarket stainless steel exhaust that probably flows better than stock.

    Any opinions on this idea? Why would you have a different setting on the inner carbs?????

    Update: in another post someone recommended 2.5 turns so this is what I went with. Tested today and found it to run well and rev nicely - in fact revs much better than the original factory setting. Probably should be tuned to be perfect, but I'm satisfied as is.
    Last edited by mektek; 04-01-2020, 11:32 PM.

  • #2
    This is the best tunng procedure hyperlink below and have used it to good effect does take some time and usually couple of days over a weekend to get through as to get buggers are hard to get to
    the different settings due to various emissions laws I basically set mine up at the time to UK spec all the way through as they had the least restrictions it seemed.

    The Jets are all dependent to some respect on all the others including the float heights do.

    to get the ideal setting takes some time I have never found there drop test where you turn the jet one way then the other till the revs drop them set it in the middle as easy to do on these 4 cylinder Motors as the other 3 produce so much power as to give you false readings

    Last edited by Lachie; 03-26-2020, 11:36 PM.
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    • #3
      Thanks for the link - lots of good info there.
      Tuning the pilot screw is a PITA - you need that special tool (a lot of $$$ for one time use) or can buy very expensive extended screws. Or, solder a piece of copper tubing to the bottom of the screw to extend it to a suitable length. And you have to remove both side fairings to get to the bottom of the carbs. I'll take a gamble on 2.5 turns and see how it runs.

      Update: confirmed that 2.5 turns is OK. It revs nicely - much better than stock. Maybe someday I'll do the tuning procedure but for now I'll keep it as is.
      There is a good reason to make it richer. The original pilot screw setting was for non-ethanol gas - E10 did not exist when the Kat was in production. Ethanol is an oxygenate which will make the engine run leaner and hotter. So when you have the carbs out it's a good idea to remove the plugs and enrich the mixture a bit.
      Last edited by mektek; 05-09-2020, 10:53 AM.