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STROKE OF POWER IN A SMALL MOTOR

Dear Tom and Ray: The first car I drove, in 1978, was a Saab with a two-stroke, slant-three engine. Friends jested that this was a lawn-mower engine, because I had to add a quart of oil to the gas tank every time I filled it up. I took their remarks as a great insult . . . to my lawn mower.

Do two-stroke engines exist on the planet anymore? My father still owns this masterpiece. Would you recommend shooting it between the headlights?
-- Bill

Tom: There are tons of two-stroke engines around these days, Bill. They're in just about every chain saw, weed hacker and gas-powered nose hair clipper on the planet.

Ray: Two-stroke engines have great advantages. Because every other stroke is a power stroke (as opposed to every fourth stroke in a common, four-cycle car engine), two-cycle engines provide a lot of power and torque in a small size. That's why chain saws use them. Do you think Lenny the lumberjack wants to schlep a 25-pound four-cycle engine up a tree?

Tom: Plus, two strokes can be used upside down, because they don't have oil-filled crankcases. So as Lenny is falling out of the tree, he can still prune a few limbs on his way down.

Ray: The problem with the old two-cycle engines is that they ran very inefficiently and created a lot of pollution. But in recent years, with the advantages of all kinds of modern pollution-control equipment that has been developed, several major manufacturers have been experimenting with two-stroke engines.

And for the record, we don't condone shooting a car between the headlights. When the time comes, we simply recommend making an appointment at Kevorkian Motors.

Charge it

Dear Tom and Ray: I have received a battery charger with the following settings: 6-volt/6 amp; 12-volt/2 amp; 12-volt/6 amp. I have a 1982 Oldsmobile, a '77 Chevy pickup truck and a Snapper rider mower. Which of the above settings should be used to charge their batteries?
-- Bob
Tom: Well, for the first two vehicles, the Olds and the Chevy, you should use the 12-volt/6 amp setting. All modern cars use 12-volt electrical systems.

Ray: The second number, amperage, is a measure of how much electricity can flow through the charger's wires at any given time. And even your highest setting, 6 amps, is not very much. A 6-amp charger would take all night to transfer enough electricity to charge your car's battery.

Tom: It'll work perfectly well overnight, but it's not strong enough to instantly charge a dead battery.

Ray: As for your riding mower, I don't know for certain what kind of electrical system it has. Many of them use 12-volt systems. The voltage should be written right on the battery. And as long as the voltage is set correctly, I think either amperage would be OK.

Write to Car Talk in care of The Buffalo News, P.O. Box 100, Buffalo, N.Y. 14240. Tom and Ray can't answer your letter personally but will run the best letters in the column. Their radio show airs at 7 and 10 a.m. Saturday on WBFO (88.7).

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