Here's a diy gudgeon pin puller that will work on 15mm pins and up.
Bill of materials:
M8 nuts x2
Plastic or metal pipe
Some notes on the construction :
The pipe should have the same or bigger length to the pin that is going to be removed, it should also have an ID bigger than the pin. A soft metal like copper or aluminum will work fine as will a plastic/ pvc pipe. I used stainless steel sheet rolled on a slip roll machine and just covered one side to protect the piston skirt.
Make sure that the LH nut (see pic) will clear both pin and piston bearing or the puller will be jammed. The washer should have the same or bigger OD of the pipe been used and the ID should foul with the M8 nut.
Self explanatory really, see the picture of the whole mechanism bolted on an old piston.
Insert the rod and one m8 nut through the pin, circlips should be already removed.
Then insert from the other side of the piston the pipe, the washer and the second m8 nut in that order. Finger tight the second m8 nut until the whole mechanism is not loose and center it to the piston.
Use a suitable spanner and continue tightening the nut until the gudgeon pin slowly pops out.