Homelite 66 compression question

[Bob Wright]

Hi guys, My son had a Homelite 66 Super Wiz given to him with a 25" bar. Looks like the old saw lots its wiz years ago. There is no compression so he thinks the rings are shot. We tore it down and the cyl looks good with no scores. I found rings but I don't know which ring to use a 50 or 51mm ring. The bore is 2" or 50.8mm. Thanks..Bob Wright
http://groups.yahoo.com/group/echochainsaws/

 

[rmihalek]

ring end gap

You'll want to have a gap in the ring when it's put on the piston. My guess is if you use the 51mm ring, the ring ends will be touching when the ring is squeezed into the cylinder. I would go with the 50mm ring and see how the compression is.

 

[mbopp]

If I remember right, the rule-of-thumb for ring end gap is .004" per inch of bore, so you'll need a .008" end gap. Or if you're metric, .1 mm is .004" You can file the ends of the ring to gain clearance if it's tight. Make sure the ring is square in the bore when measuring the end gap. The 50mm ring may have too much clearance.

I re-ringed an old smoking cast iron Briggs once, you could use a yardstick to measure the gap on the rings I took out!

 

[Bob Wright]

Thanks guys for the ring info. I will make a ring bore square on the ole South Bend to keep the ring flat and give it a measure. Thanks...Bob

 

[rmihalek]

A good trick is to use the un-ringed piston as a plunger to gently push the ring into the bore. Push the ring down with the piston a good 3/4 inch. The piston will be very square in the bore and will insure that the ring end gap you're measuring is accurate.

 

[ray benson]

This is out of an Intertec chainsaw service manual 6th edition (1980) for the Homelite Super Wiz 55, 66 and 80 models.
The aluminum alloy piston is fitted with two pinned piston rings. Ring width is 0.037 inch and end gap should be 0.070-0.080 inch. Rings should be renewed if end gap exceeds 0.100 inch. Minimum ring side clearance is 0.0025 inch; maximum ring side clearance in ring groove is 0.004 inch.

Ray

 

[Bill G]

An old Homelite dealer here still has a new 66. He has other NOS saws but the Wiz 66 is the oldest that I have seen on the shelf. I have a 550 that is new but the I want to buy the 66. I just wonder what it sold for new.

Bill

 

[BillW]

June 1971...
SUPERWiz 66 w/19" bar
W/ 32" bar