Right this is a bit of an odd one. I was riding the MC21 on a private circuit I have access to earlier today and on a long straight section I was flat out (130mph indicated on clock) when I felt the bike suddenly stutter and hesitate. I immediately pulled the clutch in and coasted to a stop, the bike had stopped running by this point. Now I’m thinking was that a seizure happening but it happened so fast it’s hard to say, the back wheel didn’t lock or squirm or anything else to make me think a seize just this power loss in the engine.
Anyway I stopped, got off,checked around the bike for any fluids etc and let it cool for a few minutes. Then I tried to kick it and it was as free as it always is so I started it up and limped home. It felt fine on the way back but I was riding steady.
I’ve done a compression test on both cylinders mainly because I had one to hand from another bike I’m working on and both cylinders are at 130psi. Now as I was removing the plug from the front cylinder I noticed the insulator was damaged, like smashed to pieces and bits of it are all in the belly pan. Ive never seen one damaged like that in 30 odd years and hundreds of bikes I’ve worked on.
Could the spark plug be the reason for the sudden power loss or do you think it was a seizure? I’ve no idea what happened to the plug unless a stone hit it at that moment?
Engine sounds fine by the way.
Sorry for the long post but I wanted to get as much detail in as possible.
Cheers
Chris.