Chainsaw Repair

The 066 came in several models. The MR (Mag Rescue) model had a 3/4 wrap, a PNW sprocket side cover and large falling dogs. The early M (magnum) model had a dual port muffler. The Arctic model had a wrap handle heater and a mini alternator in the flywheel (both AL and poly flywheels have a heated handle/carb version). There are also Aussie AUS and Canadian CDN versions of the saws. The Canadian model had a full wrap option. The Australian model came with a high output oil pump. They had light, medium and heavy duty air filter options. They came with an Elasto-start as an option. They also had a variety of carbs, some had a fixed H jet, some with heaters to keep the carbs from icing up.

Irratic idle can also be a bad L set carb. Use a tach, and set the idle at 3300 RPM, then turn the L screw either way. Set it to the highest revs that you find. Then reset the idle to 3300 again, and tweek the L screw again until you find the higest idle speed. Then throttle it to check the response. Lower the idle until the chain stops spinning. Then reset the H screw; at WOT out of the wood, it should 4-stroke/burple. If you do not have a Red Light model like I had, the RPM should be set to 13.5k. If the carb will not set right or it still runs funny, try rebuilding the carb. One of the diaphrams may be shot, or there may be a gasket leak or clogged jet.

Check for bearing looseness by pulling the B&C and clutch drum, clutch and oil pump/drive gear, and the starter. Try to move the flywheel and clutch diagonally and see if there is any play in the crank. If there is any play, the bearings are fried. They may run pretty good even with fried bearings. Finally the loose bearings will take out the oil pump gear. It is a PITA to replace bearings on an 066.

The bearing seats for all of the cases are the same. The flywheel side seal pocket for the poly-flywheel cases is larger for the larger seal.
The cylinder base mounts on all of the cases (066/660) are the same.

The poly flywheel case is wider than the metal flywheel case. This is why you cannot put a poly flywheel crank in a metal flywheel case
even if you machine out the flywheel side seal pocket for the larger seal. You've have to make a case gasket that's 4mm thick and that
isn't feasible. The poly flywheel crank is 4mm wider than the metal flywheel crank