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Thread: What carbs do racers use?

  1. #1
    apriliaforum expert emX50's Avatar
    Join Date
    May 2014
    East Yorkshire

    What carbs do racers use?

    I've created a needle carb fuel mapper - a post is here:

    There is some more work to be done re multi tapered needles, but getting two tapers to work with the current software should be doable.

    I'm wondering what carbs should have priority for people who may really benefit from the fuel maps.

    I noted that Dellorto offer a racing carb for $3k VHSD/G
    It takes the K needle, but also the AK needles - 4 pages of them.

    A lot of work... but perhaps worth it as the tuner could access the data simply with the fuel mapper.

    Perhaps there are other important carbs that really should be added.
    I thought it best to ask

  2. #2
    apriliaforum expert emX50's Avatar
    Join Date
    May 2014
    East Yorkshire
    A lot of time and effort has passed, since making this first post.

    I haven't given up on the dual taper needles, but I'm beginning to doubt the need.

    Mikuni Needles

    Much effort went into 'Mikuni needle analysis'.

    The vast majority of the published data was simply wrong.
    In some cases, it was simply ridiculous.

    Using the standard Mikuni measurements... certain needles are listed as having a taper that has a larger diameter than the needle land
    The needle dimension data is simply fictitious.
    It's an appalling lack of respect for the engine tuner, with errors to at least 30% of actual fuel flow area.

    I wrote to the major Mikuni agents.
    They aren't interested in correcting the data.

    What to do?

    I instead, calculated all the Dellorto needles that will work in the Mikuni carbs.
    ... and it is a fairly surprising number.

    Due to the atomiser length... a vast range of Dellorto needles can be used in Mikuni carbs.
    Useful to know, considering the small range of Mikuni needles typically offered.

    Needle Carb Fuel Mapper™

    Anyway... the program is now at a 'release stage'.
    It has all the Dellorto carbs, and pretty much all the Mikuni carbs.
    ... that being the needles and atomisers for each, against carb bodies.

    It may not be entirely a complete database... but it is going to be pretty close.
    I spent a lot of time cross referencing different supplier sites.

    There's more work that can be done, but it seems likely that the release version will help most people who are interested in carburettor tuning.

    Carburetor Tuning For Performance

    To this end, I've decided to make a video series.
    The objective is to look in detail at the different circuits, and how they affect the fuel flow.

    It is likely to be an open ended series.
    The first, outlines the challenge, and introduces the concept of 'fuel mapping' as the better way forward to understand carburettor tuning.

    Have a look and see if you think that it can help you.

  3. #3
    apriliaforum newb
    Join Date
    Nov 2017
    Thank you for your information and advice, some good stuff here!

    I have not used carbs for some time but have had to revisit them to race my 1981 GS1100 in the vintage series in my area.
    One group I have been following with some great information is Lectron Carbs, take a look at the site, good info as well.
    If I can get the carbs approved I will use them for my vintage bike..

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