Part 4 - Component by Component
The T1 carburettor must only be used on the T1 engine type, and the T2 carburettor on the T2 engine type, both standard and unmodified. However all carburettors are subject to normal dimensional criteria. Overall length (manifold face to airbox face) is 53.9mm min and bore go / no go gauge is 13.2mm / 13.3mm. Pilot jet size 35 only, the mixture screw tang can be removed.
The T1 has 140 stamped on the throttle valve and four small holes just below the mixture screw point. The T2 has 150 stamped on it, with only three holes at the same point. (see Appendix note 1). When used as a Cadet or Junior engine, only the official ABkC restrictor plate (which may be de burred) must be fitted between the carburettor and insulator, and have an opening of no more than 16mm diameter (see p.8). This size may be altered during the year (see p.7). A 2mm hole may be drilled in the tag on the restrictor for the purpose of affixing an official seal. This restrictor is not permitted in Senior engines.
6. Permitted main jets
size 65 (PN 99101-ZK7-0650) size 68 (PN 99101-ZK7-0680)
size 70 (PN 99101-ZK7-0700) size 72 (PN 99101-ZK7-0720)
(jets may be brass or silver in colour)
Emulsion tube must be either part number 16166-ZH8-W50, 16166-ZH-810 or 16166-Z4M-922 (see drawing 1 in Appendix 1). The throttle-actuating arm can be modified to accept an actuating rod onto the throttle butterfly, a method of mounting a throttle actuating cable and a method of mounting a throttle return spring only.
7. Carburettor air box
Must be standard and unmodified. The additional silencer, part number 17235-ZE1-831 may be used.
8. Air filter
The original air filter, if used, must have the base washer in place, it can have it’s paper or foam or both removed. Alternatively it can be omitted completely or be substituted for another filter. In any case, the plastic outer cover must remain as standard, unmodified and fixed securely in its original position.