toydoc
Member
Use to be a issue long ago. Not so much any more. Whats the ring end gap at BDC, 1/2 stroke and TDC? Keeping the ring end gap on the tight side of spec will keep the pin in place. Also the off chance that a big exhaust port may not help also. When hot the ring may push out on ex side, that opens ring pin side. Pin ends up in intake/reed then on piston.
I have seen this happen.... also have seen the space between the rings break off.
i remember back in 98, yamaha had a recall for the 97 vmax 600 for that happening. my brother's sled was found to of backed out and the ring was just spinning on the piston! caught it just in time before the ring caught on the port and caused a big mess!
skidooboy
New member
spi pistons are known for this problem still today. ski
Magic I had one do that on my 1000. It was a wiesco and the ring spun and broke. Peppered the head but did not hurt cyclinder.
RJH
New member
Had one go on my brand new blaster ATV. We drove it for two years like that – just hard to start sometimes – but ran strong. It was always WOT so couldn’t tell. I got it for cheap from a buddy dealer so I didn’t push the issue. I kept looking inside the exhaust hole and compression was not too bad – so I just left it.
When I didn finally pull it down - The head mechanic said the cylinder was toast, when I did take it apart.
I took it to my old race mechanic and he simply bored the cylinder off set. Piston didn’t care – she still runs real strong today. Piston and ring from eBay.
The pin left OK but the ring rotated then stopped - bending it in and did some cylinder wear damage.
When I didn finally pull it down - The head mechanic said the cylinder was toast, when I did take it apart.
I took it to my old race mechanic and he simply bored the cylinder off set. Piston didn’t care – she still runs real strong today. Piston and ring from eBay.
The pin left OK but the ring rotated then stopped - bending it in and did some cylinder wear damage.