The oil screen on the Ninja 250 should be removed and inspected with every oil change. If there are any metal shavings or particles trapped there, it could mean a big problem. Steel shavings are the worst. You can tell them from aluminum shavings because they will stick to a magnet.
Below is a link (click the image) to a PDF file that will allow you to make your own Oil Screen Gasket for your Ninja 250. I am told this works on all Ninja 250's. You'll need some gasket paper from the local auto parts store and a printer that will handle thicker paper. Print out the image full scale on regular paper first. Once printed, verify the scale by using the scale marks on the image that you have printed. They should both measure 50mm. If not, then you may need to adjust your printer settings until you get the scale correct. Most printers will default to the correct scale.
Once you are certain the scale is correct, you can print the gasket onto gasket paper. When done, cut the gasket out using scissors and a hole puncher. You are ready to replace your oil screen cover.
Depending on the type of gasket paper, a laser printer may work better. In a pinch, it is possible to use ordinary thick paper. A cereal box or pizza box usually has some that can be used.
NEW: Here is the Clutch Cover Gasket
The Clutch Cover Gasket has to be printed out on a wide printer capable of printing on 11"x17" paper. If you don't have one, you might be able to take your gasket paper to an office supply store that offers printing services. The actual gasket is only about an inch too big for 8.5"x11" paper.
