KR-1S.co.uk Forum

I have 2 sets of pistons & 2 have got 4 holes in the skirt ( I assume this is for little end lubrication ?) the other two are just plain ie without holes.
My question is should I fit the 2 pistons with the lube holes in, or 1 with holes & 1 without ?
If its a mixture, which go's to which side ? as I cant find any reference in the manual.
Cheers

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As the piston decends on the power stroke the charge in the crankcase forces a little mixture from under the piston through the holes to the cylinder wall

They are there to provide extra lubrication on the hotest part on the ring that bears onto the exhaust port

The 2 pairs of 2 holes run down each side of the main exhaust port inbetween sub exhaust ports

IF 12 o'clock is the exhaust pipe (main exhaust port), then 1 pair of holes at approx 11 oclock and another pair at approx 1 oclock
the holes are to face the front wheel NOT THE BACK WHEEL
the holes should run a path down the cylinder wall without ever going through port window (each side of the main exhaust port)

if your piston is blank (no little holes) then you can drill some in
the grey stripes on a Kawasaki piston are a dry film lubricant (Molybdenum Disulfide (MoS2)) that eventually wears off and is a quite good indicator of when you should think about replacing the top end.
(as well as when the tiny machining ridges running around the piston disappear)

the right hand piston is KR-1/KR-1S the left is KMX125 for KR250S

picture by STROKERBOY

Excellent, thanks for that. So are we saying that the pistons with the lube hole's are the correct ones & these can be fitted as a pair ?

Greetings help me please the sizes of the piston the size of a finger, height of the piston and on what distance from a bottom of the piston to the finger centre are very necessary. I can not find the piston I wish to give that to me have cast them but I do not have sizes.