Hello? Are these genuine wm20 rings?

Hi Kalle..Yes, they are genuine. Some original pistons had them cut at an angle as yours are....Ian

email (option): julie@wright52.plus.com

Thank You! They are in very good condition and then I will use them. Intresting how shoud I measure ring gap?
seems impossible to me.

With the feeler gauges at right angle to the stroke dimension, i.e., parallel to the ground when the cylinder is upright. Fortunately the M20 bore is large enough that there should be no interference with the opposite wall.

email (option): jonny.rudge@verizon.net

These rings make your thumbs hurt when you remove them

email (option): ahum@quicknet.nl

These rings can hurt your thumbs when you remove them

email (option): ahum@quicknet.nl

Kalle. put each individual ring in the top of the cylinder and push it down about 12-13mm with the piston to keep it parallel in the bore. Now check the gap with a feeler guage. If the gap needs to be opened up? Hold the ring just off the edge of a firm surface, like the top of your vice. Then gently remove some of the end of the ring with a fine file. Ron

email (option): ronpier@talk21.com

Then diagonal gap should be less than usual? Half? Good point, I will be careful with my thumbs. Thank you all.

No Kalle, if the instruction manual asks for say an eight thou gap. That measurement will apply whether its straight or diagonal. Ron

email (option): ronpier@talk21.com

It seems to me that if I leave diagonally (let's say 45 degrees) .008" I will really have gap about .011"

No Kalle. If you slide the feeler gauge in the diagonal gap, 8 thou is 8 thou. For instance if the ring were to expand say 8 though, the gap would close. It seems to me that your theory diagram would suggest that you only give a gap of about 2/3rds the required amount and therefore if the ring would expand 8 thou it would then seize.....Maybe someone with engineering experience can explain it better? Ron

email (option): ronpier@talk21.com

Hi Kalle..If you took a measurement say...every 5 degrees from horizontal to 45 degrees you would get a fractionally different measurement every time ranging from .011 to .008"
The gap is measured at 90 degrees to the face of the slot. Here you would get an .008" feeler in...if you removed that feeler and tried to put an .011" one in it wouldn't go...Ian

email (option): julie@wright52.plus.com

Thank you all!