Having cleaned out all the screw threads and oil passageways I started to assemble my engine. The first thing to go in was the aforementioned valve and I decided to wash out the pump to filter passageway just in case there might be some cleaning medium or 50k miles worth of sludge left in the blind hole part of the passageway. With the valve in place and the crank case upside down on the bench, it’s easy to squirt some petrol or white spirit into the passageway to wash it out. The fluid then collects in the top of the filter chamber and you can reuse it or see what washes out. I soon realised, when the bench became wet, that the valve wasn’t seating. So I removed the valve, cleaned it out and reassembled it. This time I checked the ball was seated first and to my surprise it was about a 1mm off the seat.
So, my question is: - what should the free length of the spring be?
Mine is 14.5mm long and I recon it should be at least 16mm. The Kawasaki manual makes no reference to it other than its there and how to take it out. I recon it is important as a week spring will mean the valve will open for the slightest filter congestion. A strong spring will result in a high pressure and hence a highly clogged filter before the valve opens. But we know the oil pump is designed to deliver quantity not pressure so a high pressure could result in no oil flow at all. Having said all that the real answer is to change the filter regularly but if anyone can shed any light on the free spring length it would be much appreciated.
A2 1979-80. A1 1980-now
