well if you see what i found out...you were kinda on track...only not carbon or oil but a land pinch forcing the ring out opposite exhaust side causing a high roll over friction in one part of the stroke ..
REAL STRANGE PROBLEM
- Thread starter m8magicandmystery
- Start date
well if you see what i found out...you were kinda on track...only not carbon or oil but a land pinch forcing the ring out opposite exhaust side causing a high roll over friction in one part of the stroke ..
Nice
Squish must have been a little tight eh? When I raced 6.5 briggs I added a stroker kit to the engine and forgot to change from my shaved head to more stock head and after about 4 laps power REALLY picked up. Went home, tore it down to check wear and ya, the piston hit the combustion chamber just enough to pinch the ring sad thing was it scored the cylinder and that was that....
Squish must have been a little tight eh? When I raced 6.5 briggs I added a stroker kit to the engine and forgot to change from my shaved head to more stock head and after about 4 laps power REALLY picked up. Went home, tore it down to check wear and ya, the piston hit the combustion chamber just enough to pinch the ring sad thing was it scored the cylinder and that was that....
i don;t suspect the squish because of the pinch only relative exactly at same points exhaust side and the power valve relationship. I suspect the power valve clearance was right on the edge originally and with the power valves possibly opening at an higher rpm then they should have that the valves may have floated up the few thou that they have for clearance and just wore the top of the stop in the head a tad and the bottom of the stop on the power valve a tad and then just a micro thou into the chamber to do a micro pinch....lol..anyway glad i found it...i never felt good about the bellow style STMs..
Your sure the sled wasn't running lean at any rpm causeing those pinched lands near where your wash would be indicated, I pulled my 800 which was doing similar apart and put back to 600 stock. The pistons etc are perfect. My recoil was binding on gouged basket deal bolted to the mag. Filed down marks & works perfect now
nope she wasn;t lean imo..zero signs of lean issues on piston edge and i have afr and egts and never any lean readings and plugs always good with good wash..
I had to file the basket from bdx...the titanium one to work properly originally..if time soon i will add some pics..
I had to file the basket from bdx...the titanium one to work properly originally..if time soon i will add some pics..
