if your sight glass is so dirty on the inside you have no idea if you have oil in your engine or not, it might be time to seriously think about replacing it. i ordered mine from the usa from an ebay seller called "dt400man" theres a photo of the sight glass and on the rubber surround on the sight glass it says LG 25 12 -2 it also says it fits these bikes SUZUKI OIL LEVEL WINDOW ALT125 LT125 DR GS750 GS850 GS1000 GS1100 SP125 SP500when you get the new sight glass, put it in the freeze for about 24 hours to shrink it a little and make it easer to install to the clutch cover. to replace the sight glass on the Across, the clutch cover needs to come off.now, if you bike has oil in it, when you remove the clutch cover, oil will pour out all over the ground. theres a few ways to avoid this first you can wait till next oil change, and when the oil is drained, remove the lower fairing off the bike and then remove the clutch cover or if you want to do it while theres oil still in the bike and you want to do it now, then remove the fairing off the bike and grab a swag and some pillows and find some nice grass. put the bike on the side stand on the grass and put the swag and pillows n the oeft side of the bike. lift bike off side stand and slowly and gently lower bike on to the swag/pillows. move the swag/pillows to the are under the left handle bar/top of the engine. the bike will be at a fairly large angle but still easy enough to work on and oil/fuel wont pour out of it all over the floor now once the clutch cover is removed you need to remove the sight glass. the sight glass is extracted out the back of the clutch cover, towards the engine, hence the need to remove it in the first place. if you look at where the sight glass sits in the clutch cover, it has gasket sealer around it. scrape this back with a sharp knife/small flat blade screw driver. pop out the old sight glass. this wont be an easy task, do what ever it take to get it out once its out, clean the hole where the sight glass was and get rid of any crud left in it get the new sight glass and press it in nice and square. i put the clutch cover on a rag on the floor and pressed either side of the metal surround of the sight glass with a biggest a flat blade screw driver i could lay my hands on once it is in nice and square and flush, put some gasket sealer around the rear of the sight glass from the fight glass rubber to the clutch cover to be extra sure you dont get oil leaking thru the sight glass put it all back together and yuor done