Rattle on Overrun - Sanity Check
Posted: Thu Dec 12, 2019 11:52 am
Hi All,
My now sorted 1984 KR250A starts, goes and rides fine. However, when riding it hard, I can hear a slight top end rattle on the overrun between gear changes. The bikes has done about 11k and runs spot on. I know the early KR’s had a reputation for catching piston rings in the ports, so is this a sign of impending self distraction?
I can’t decide if it is rings, piston slap or small ends. It’s been there since getting the bike and hasn’t got any worse over the last 1000+ miles, so before I needlessly strip the top end, has any of you KR250 owners experienced this, and if so, is it the infamous ‘normal’ or something I need to address PDQ?!
Meanwhile, all looks clean on the piston skirts when viewed through the exhaust ports. My next step was to do a compression test and borrow a mate’s endoscope to poke into the plug holes to see if there are any other tell tale signs or marks. Hope I’m wrong, but my other water cooled 2 strokes are all mechanical quiet on the overrun. The KR reminds me of my old air cooled 2 strokes....
My now sorted 1984 KR250A starts, goes and rides fine. However, when riding it hard, I can hear a slight top end rattle on the overrun between gear changes. The bikes has done about 11k and runs spot on. I know the early KR’s had a reputation for catching piston rings in the ports, so is this a sign of impending self distraction?
I can’t decide if it is rings, piston slap or small ends. It’s been there since getting the bike and hasn’t got any worse over the last 1000+ miles, so before I needlessly strip the top end, has any of you KR250 owners experienced this, and if so, is it the infamous ‘normal’ or something I need to address PDQ?!
Meanwhile, all looks clean on the piston skirts when viewed through the exhaust ports. My next step was to do a compression test and borrow a mate’s endoscope to poke into the plug holes to see if there are any other tell tale signs or marks. Hope I’m wrong, but my other water cooled 2 strokes are all mechanical quiet on the overrun. The KR reminds me of my old air cooled 2 strokes....