Technical: Carbs: Model M
Various Authors

The venerable Linkert Model M carburator was used on the 1952 – 1956  K, KK, KH and KHK, as well as on the racing models of that period. The K and KK's Model 53 is revered for its unusual "bombsite venturi", while the KH and KHK's Model 53-A1 was fairly similar to the well known M74B carb used on Big Twins. And then there was a 53-A, which is somewhat of a mystery.

The OSKRG's Identification Guide and What Fits What - Version 1.0 (PDF)

Quick Reference for Initial Adjustments

When you get your carburator completely out of whack, here's what to do...

Note: These illustrations are generic Linkert Model M carburators

A carburetor may be adjusted as follows: Turn both low and high-speed needles all the way in (clockwise). Back out the low speed needle five turns. Back out the high-speed needle two turns. With needles in these positions, the engine will start but the mixture will be too rich. Advance spark all the way or nearly all the way, whichever is best. Warm engine to full operating temperature and correct adjustment of both needles.

Adjust low speed first, with engine at operating temperature and idling. Turn needle in, one notch at a time, until mixture becomes so lean that the engine misses and acts starved. Back out the needle five to ten notches, or until engine hits regularly with spark advanced and throttle closed, or as nearly closed as it can be set and stlll have engine run at idling speed.

Adjust throttle lever stop screw (5, Fig. 3F-9) to make engine idle at desired speed with throttle fully closed. Turning screw clockwise m@es engine idle faster. Never set idle adjustment to slowest possible speed. An extremely slow idle causes bearing wear, oil consumption and slow speed accelerating difficuly.

Make final readjustment on low speed needle. Try one notch at a time, first in and then out, to see if engine picks up speed or runs more smoothly. Starting and all around carburetion will be better with low speed adjustment set slightly rich rather than lean. If necessary, make further adjustment on idle stop screw to obtaln desired idling engine speed. Retard spark completely. If carburetor is properly adjusted, engine will continue to run evenly and smoothly, though more slowly. During high speed operation, fuel is metered by a fixed jet which has no adjustment. However, the high speed needle may be used as "trimmer valve" to supplement the fuel flowing through the jet during extremely high speed operation (opened amount which achieves best results). It may be closed during operation at high altitudes to keep mixture from becoming too rich in the rarified air.