Hartop M

Discussion in 'Help Wanted' started by matth, Sep 29, 2013.

  1. matth

    matth New Member

    I got the mag bracket fitted and managed to make something up to drive the mag temporarily, but I cannot get it to run very well, it starts easily, on the flywheel, and keeps up a fairly regular speed but the firing is a bit erratic, the timing is pretty much spot on, I was wondering what the tappet clearance is for the exhaust, and thought maybe the inlet valve spring is a bit weak because when it is running and you put some load on it it tends to chuck a bit of smoke/vapour out of the carb

    it also bounces around a lot when running, the other ones I have seen seem to run fairly smoothly and quietly, do they tend to run quite well in general?

    This one here seems to run quite well and seems to be nicely balanced
  2. Numpty1

    Numpty1 Member

    Firstly is the mag good?
    On no load these engines 8 stroke, that's normal and to be expected, you can play around with valve springs, timing etc. and may improve it but that's down to you. Don't forget if that carb is a made up affair it may only deliver the right mixture at a certain speed or could be miles out.
    The inlet valve springs are thin and are therefore often weak. Philip Daintree has the spec for replacement springs and can supply them, worth getting an exhaust one too. As a try out you could make a collar to fit round the base of the valve guide and this will raise/squash the valve spring a bit and give you some more strength.
    From my experience of running these on little or no load, you need to richen the mixture otherwise they hunt on the governor. That means enlarging the pilot jet slightly (one or two thou's).
    The engines are not particularly well balanced. They run best (smoothest around 600-650 RPM) but it depends how good a casting your flywheel is as to how balanced it is (this may sound a bit double dutch because the flywheel is meant to be out of balance anyway but one side may be like an aero bar inside). You may have to experiment with speeds to see where it is smoothest or if there is no smooth speed have a go at balancing with sticking bits of lead on the inside of the rim.
  3. matth

    matth New Member

    I put in a new condenser as it was sparking on the points and it improved slightly, I might make a choke flap assembly to go on the stub like the carb in the picture, also put a slightly stronger inlet spring and it doesn't run too badly now, it is now half dismantled ready for paint stripping etc, which I am not looking forward to!

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