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  1. #1
    ...On the Grid... gbowie's Avatar
    Join Date
    Jan 2006
    Location
    East London, South Africa
    Posts
    30
    Has any one had any experience of using bored out carbs on a TZ.
    I have recently acquired a '91 3YL with 4DP barrels and CDI and on investigation found that a previous owner has bored the carbs to 39mm.
    The bike pulls well, but tops out between 11-11.5k, I have checked the power jets (found one with a broken wire and repaired this) and they get 12v at high revs in neutral .
    I have done a check on the settings and find as follows :-
    Mains...420
    Power jets..80
    Pilot jets..20
    Nozzels... R 3 ?? (Unlisted in the parts manual)
    Needle clip.. one richer than middle.
    air screws.. 1 turn out
    Squish.. around 0.8mm .
    Timing.. 1.59mm BTDC.
    I am running at sea level using 102 octane leaded petrol and Motol 800 (motocross) at 30:1.
    Has anyone any suggestions as to what difference the extra 1mm bore dia would make to jetting and why it won't rev to ( I'm told 12500-13000).
    Also it won't idle, but I suppose that comes with buggering around with the carbs.
    Any ideas.
    Geoff.



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