Upgrade to enjoy this feature!
Vital MX fantasy is free to play, but Premium users receive great benefits. Premium benefits include:
- View and download rider stats
- Pick trends
- Create a private league
- And more!
Only $10 for all 2026 SX, MX, and SMX series.
Detonation = running lean.
That head has what appears to be some effects of a prior failure also…
Dug further and figured out the crank stuffer exploded and that’s what’s melted on the top of the piston. Is this caused by detonation? Bike didnt seem lean at all. Spark plug is black looks just a tad rich how I like it. Cylinder is pristine and piston was nicely oiled when I pulled it apart. Did notice there was an air leak on the reed cage where fuel was slowly coming out but I could feel a decent amount of air leaking from it. Maybe the cause?
Your bottom end/ crank is coming apart…time to split cases & open wallet..
The Shop
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
Yeah I figured. Unfortunate. Thanks.
Post a reply to: What causes this too the piston and head?2002 yz125