Matchless G3l

[Marley 02]

Hi, I have been renovating a 1955 G3l, the engine smokes although I have checked the bore /piston/rings/all within tolerance,the rings are not inline, the inlet valve oiler is set to a third of a turn out,the sump has been emptied, but still there is fresh oil in the cylinder I was wondering if the crankcase breather was faulty hope not as I will have to strip the primary drive etc any thoughts.
Pete

[clive]

try reducing the inlet valve oil setting. the breather is just a flap valve and would have to have failed closed to cause any oiling of cylinder. Add a clear plastic pipe to the end of the breather and see if there is any air pulsing out.

[Marley 02]

Hi Clive,
thanks for the info, i already closed the inlet valve oiler , unfortunately there is no copper extension pipe on the breather, will find another way of checking, thanks again.
pete

[Marley 02]

Hi all,
after a topend stripdown /inspection, the engine now pulses have adjusted carb settings, but it still persists, any thoughts?
Pete

[clive]

next thing I would check is wear between the valve stems and valve guides. Too much and oil will find its way down from the rockerbox.

[Marley 02]

Hi,
I have renewed the valve quides so that's not the problem, it's a mystery?
Pete

[Duncan]

H I have checked the bore /piston/rings/all within tolerance,the rings are not inline,

Are you at the top end of the tolerances? When I broke the crank on my twin I renewed the piston rings as everything was just within tolerance, after running in it burnt oil and pumped it onto the top of the pistons, a rebore was the solution.

It is worth noting that some piston rings have a tapered face and must be fitted the correct way around, there is usually a mark on the top.

[Marley 02]

Hi,
another slight problem is the engine pulses when started, difficult to get a steady ticker, don't know if this has any bearing on the oil in cylinder mystery?
Pete

[SPRIDDLER]

A couple of questions:
- What exactly do you mean by 'pulses'? Missing a beat on tickover? (It may be that the excess oil is intermittently fouling the sparkling plug).
- Do the revs rise and fall (pulse?) at above tickover speeds?
- Is this with bike on the side stand?
- Is the carb jetted correctly and has the right slide?
- Are sure it's oil smoke (i.e. blue) and not unburned fuel (black smoke) from an over-rich mixture? That would cause 'hunting' (pulsing).
In theory, if the c/case breather isn't functioning you could try relieving some of the c/case pressure by removing/loosening the rocker box cover plate.
BTW - When you are adjusting the carb bear in mind that it is only the Pilot jet that feeds fuel to the engine at throttle openings up to about 1/3rd open. Check that it is absolutely clear of any blockage or restriction. The ethanol in today's fuel does tend to gum up the tiny jet holes and Pilot jet drillings in the carb.

Monobloc pilot drillings (511x640).jpg

And drillings nos. 31, 7 & 8 here: (Force air, aerosol pressure carb cleaner or WD40 through to check they are clear).

Monobloc Pilot screw side.JPG