XR400 Sump Strainer So... I picked up a '98 XR400 a couple weeks ago. It started on the first kick, ran smoothly, no smoke. I could tell she liked me, and she followed me home. Cool. Oil & filter change went smoothly, as did a cleaning of the frame downtube strainer... a very few small bits, but nothing major for a 15-year-old bike. I didn't check the sump strainer quite yet, as I didn't have the right-hand side-cover gasket, and didn't have any other reason to go in there. Further mechanical meanderings revealed an overly-stretched (don't blaspheme) cam chain. The tensioner spring is good, but has no more travel. Okay, that's two reasons to go into the right side of the case... cam chain and check the oil strainer. Hol-ee shiiiit! The ruler wasn't in there, really. This pile of scrap isn't from my piston. The bike starts and runs with no smoke, and there wasn't a speck of debris anywhere else in the entire sump... just in the strainer cavity. XR400 Sump Strainer. Remove the bolt (10mm head) and slide the strainer out. Not my photo. There is a line of black RTV between the cylinder and case, indicating a reassembly somewhere along the line. I believe after a previous piston was nuked, a mechanic didn't know about the existence of a sump strainer in Honda thumpers and let it pass unnoticed. I was familiar after having done some kick-starter work on my beloved old XL250 years ago. I removed my oil pump and back-flushed the pick-up tunnel, then flushed out the debris with kerosene in a large syringe. Medical types will recognize this procedure as 'lavage'. I lavaged the hell out of it. My sump is now clean enough to eat off of... if you don't mind kerosene residue. So... a kind note to mechanics out there: Please look for, check, and clean sump strainers, especially after major engine work.