Greasy Saturday – LML 125 4t Valve Clearance Adjustment

The weather is fantastic this weekend, so obviously I choose to stay indoors and go trough the valve clearance check (and oil change) on the LML.

Yes…I make questionable decisions sometimes, but the fact is the poor little bike was in need of some love and I’d been delaying this for the last 3 months.

It was my first time doing a valve clearance check (and adjustment) and I’m not going to write up any kind of tutorial as I’m far from an expert on it. I can however share a couple of things I discovered and that might be useful to you given the relative lack of online info on this bike. (and the very synthetic workshop manual).

First of all, if you are indecisive on whether or not to do it yourself, go for it! You’ll have a hard time finding a more basic engine to work on. It’s 2 valves only and the adjustment is done with locknut&screw (no shim under bucket shenanigans here). Check the video I linked to previously, read a bit about valve checking/adjusting to understand what is what, have a look at the LML workshop manual and go for it.

Secondly get a set of proper metric feeler gauges, mine is in inches/metric making things unnecessarily more complicated (Valve clearances are Inlet: 0,06+-0,01mm | Exaust: 0,08 +-0,01mm |I only had 0,063 0,076 0,102 so had to work with that)

Third: ignore the valve clearance adjustment tool, they are usually only sold in sets and cost around 35€. With only two valves to work on, it’s easy enough to just use a small needle nose plier do make the adjustment.

Fourth: You shouldn’t need any type of liquid gasket for the valve inspection ports as they have a rubber o-ring seal that shouldn’t need replacement nor additional seals. I was afraid they used liquid seal and therefore would need new sealant to be applied but no.


And final piece of advice: good luck finding the TDC mark on the flywheel/magneto cover! Ended up removing the cover and to make life easier to anyone trying it I would recommend you do the same. Remove the spark-plug, remove the flywheel cover and then turn the engine by hand until you see the inlet valve dip and return (open & close) then align the mark with the one on the cover (by aligning the cover back in place). Check there is some play in the rocker arms and then check clearances.

TDC mark on the magneto cover
TDC mark on the magneto cover

My bike’s intake valve was a bit loose, so adjusted it to 0,063mm, the exhaust was somewhere between 0,076 and 0,102 but closer to the smaller so probably within spec: 0,08+-1 mm.

Inlet Valve Cover
Inlet Valve Cover

Checking clearance on Inlet side (the exhaust is a tiny bit trickier)
Checking clearance on Inlet side (the exhaust is a tiny bit trickier)

After checking valves, it was time to warm up the engine and change oil.

Quite dirty oil (although it hasn't covered a big distance, the change is overdue by a few months...)
Quite dirty oil (although it hasn’t covered a big distance, the change is overdue by a few months…)

And new oil in! Using Castrol Power RS 10W40 full synth which is definitely overkill for a low tech engine with a small yearly mileage but it’s what I had around because I use it on the Ducati.

P1150186 (Copy)

Hope this was useful! I must admit I was a bit nervous about doing this myself but the fact is it all took about 2h30 and was quite straightforward.


2 thoughts on “Greasy Saturday – LML 125 4t Valve Clearance Adjustment”

  1. Serious respect here mate as I wouldn’t even consider doing valve clearances on anything. I know my limits!

    1. I had two things helping:
      1- single cilinder air cooled engine
      2 – not my bike!

      Joking apart, I should’ve done this during last year’s service but chickened out. Finally decided to give it a shot this time around.

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