Bad rhythmic vibration at idle.

[windcalmer]

Qmb139 with a big bore kit. Had been running fine for months with the big bore kit installed. Suddenly there is this rhythmic vibration at idle. It cycles every 1.5 seconds give or take. It shakes the entire scooter enough that you can see the frame, mirrors, and engine shake. The wheels are not turning so it's not the variator or the wheels. This happens while sitting still. It gets a bit better and just vibrates the normal amount at speed.

Just trying to figure out if this could be the cylinder causing this type of thing. Any ideas would help.

Thank you in advance.

[GrumpyUnk]

Think on it a bit. You have the same parts, and now they are shakin' around. That generally comes from things adding or losing weight(tire wear and imperfect rubber density changes, mud on the i.d. of a rim), or things getting loose, and moving around on the rotating crankshaft.
I would check the flywheel and variator to see that they are tight and not moving in any way. I can't think of any other bits that could move and cause vibration. If you have picked up road stuff, and it has gotten into the blower wheel on the flywheel end, it could cause imbalance.
Hopefully, the piston & rod have not gained or lost weight... that could be 'interesting'.
tom