LCGB Forums

So after 3 weekends, 3 tins of gas, 2 club hammers and 10 litres of diesel, the piston is refusing to move.
I was hoping to get it free so I could reuse the standard 125 cylinder and crank, but now I've got the crank turning and moving the cylinder away from the block, I was able to remove half a cup of what looks like mud from around the crank.
There's a lot of sideways movement in the con rod and it looks like it's junk. Now I can cut the rod and move forwards.
As 125 cylinder and piston kits for the Li's don't seem to be available, I've decided to go to a 150 kit as I'm not really looking to improve performance and I need to keep costs down.
Scooter Restorations list some SIL GP150 kits. Are these a straight swap for the Li125 bits, because I've read the crankshafts are different, so didn't know if the pistons etc. are different too?

Secondly, there's a choice of Borgo or Mahle piston. Both are the same price, but is one better than the other?

Out of curiosity, any idea what all the 'mud' is doing in the engine? Is that how oil goes if it's left to sit for a couple of decades? I'll try to upload some pics in a minute.

There is a lot of sideways play on Li cranks, as they are centralised by shimming at the small end of the conrod.

If you cut the conrod to allow the removal of the barrel and piston, then you will need a new crank, so don’t worry too much about the GP and the Li having different cranks. The difference between the two is that the GP has a fatter taper beneath the flywheel. However, changing to the crank will also require a change of flywheel to suit the fatter taper. However, if you ever push further for a bit more more power, the GP crank will cope with it.

You might have already opened a can of worms, but don’t worry, the answer is out there somewhere.

Shimming at small end on LI cranks?
That was the SX motor.

you could try drilling a ring of holes around the crown of the piston, this will hopefully allow you to get it separated from the crank and break/cut the rest of it up..
then the barrel will be slavagable (maybe with a slight rebore) and if you can find a oversize 125 piston you will be back in business..

howver it may be the crank is irretrievably damaged, although it may be possible to clean up the webs and get a new con-rod and bearings fitted, this will save changing crank/flywheel etc (although you can get LI/TV cranks if preferred, which will be ok on a standard spec 125)..

I’ve got a 125 special barrel piston head and crank and also the same of a go 150 if interested

I was trying to work out if the drilling option was viable, but I couldn't find a decent enough photo of the back of the piston to work out where to safely drill.

Thanks Daniel.
Is the 125 Special exactly the same as the series 2 Li125 engine wise?
What sort of condition are they? Would I get away without a rebore and how much would you want for them?

(I may be alone, but cannot see the images fully. The way that some image hosting sites operate is ridiculous! Thank Goodness for Dropbox.....)

Perhaps I am misinterpreting everything, but as the piston is wrecked anyhow, I would choose the biggest hole saw to suit (smaller than the piston 'bore') & carefully drill concentrically through the crown so that the piston will then allow the barrel removal & access to the wrist pin & crankshaft.....

Don't get me started on uploading the pictures.

Presumably I'd need to drill through both sides the wrist pin after going through the crown of the piston, in order to be able to free the barrel?
Forgive me if I'm getting the wrong end of the stick, but I've not seen one of these pistons out of a barrel before.

To make things more interesting, the piston is stuck at BDC.

Removing the piston is easy...….

Step 1: give up hope after using heat, oil and force and get the grinder out.
IMG_20180902_102014 by mick leaf, on Flickr

Step 2: keep on going and give up hope of salvaging the crank.....
IMG_20180909_131242 by mick leaf, on Flickr

Step 3: Success !!
IMG_20180909_132553 by mick leaf, on Flickr

Step 4: debate whether a bit emery cloth will be enough to save the piston
IMG_20180909_132557 by mick leaf, on Flickr

Good luck but be prepared for the worst...….as shown above

PS...….the mag-flange came out in bits as well

My mag flange is also being a nightmare. Guess I have that to look forward to next.

With stuck magneto flanges, the longer they are in soak with penetrating oil/diesel, the better.

If possible, try to remove all of the six M6 fasteners completely, especially studs!

Construct something in steel, using plate or box section/tube that can be used as a lever utilising the two M6 extract holes. The lever should not be used as an attempt for pulling the flange out, but just to free off the thing via rotation, CW & ACW repeatedly.

Any other methods will probably wreck things, but with patience, once it can be freed off a little, it will come out....

Sorry it’s took a while to reply the wife has been cracking the wip on the decorating , they are in good condition as I recall best thing is for you to come look at them if your not to far away I’m in Sheffield

I'm a bit too far away for that I'm afraid. I live on the Herts/Beds border.

I have made some progress with the seized piston though.
After a couple of weeks of soaking in diesel, a lot of cans of blowtorch gas, a can of freeze/release spray and a lot of hammering, I decided it was time to cut something.

There was a couple of millimeters gap by the small end, so initially I thought I'd get a Dremel cutting disc in the there and cut the gudgeon pin.
I was worried that half the diameter of the disc was less than the diameter of the pin, so I decided that was out. Then I noticed I could get to the back of the piston and decided that the aluminium piston would be easier to cut than the pin which I assumed was hardened.

I set about grinding the back of the piston.
It was fairly easy to grind it away, with the biggest issue being the sanding drums rotating on the rubber Dremel bit.
A bit of perseverance and I was able to remove the piston and barrel, leaving the pin in the con rod.





The remainder of the engine has gone back into the drum of diesel, this time covering the mag housing, as that's my next battle.

So the only thing I know that is definitely damaged is the piston.
I'll try to get the piston out of the barrel, to see what it's like where it's been stuck, then I need to carry on taking the engine apart to get the crank out for a proper examination.
It may all turn out to be junk, but who knows.