I have only ever known that lawnmowers were 4 stroke, but were they commonly 2 stroke and when?
Lawnboy is the only two stroke brand I remember. That was in the 60s - 70s. I believe there were some commercial models made as well, but they might have also been Lawnboy.
There were others besides Lawn-Boy. I had a Wheel Horse one. I made a lot of money with it that summer. I do recall that in the 60s and early 70s, the cheapest rotary mowers sold at places like Montgomery Ward, Sears, and J.C. Penney were often 18-20" 2 stokers.
they were cheaper models. major brands might have a model or two on the low end.
For $10 I bought an elderly 2-stroke LawnBoy about 20 years ago. It gave reliable service for 11 years - at which point I sold it for $10. A fine machine.
But Lawnboys weren’t the cheaper models, they were a full-price one. IIRC they had a good reputation for reliability.
And I don’t recall the other brands having a two-stroke model as their low-end offering. In my recollection the cheapest models were always four-stroke.
I remember seeing some relatively nice mowers with 2-stroke Suzuki engines in them from the 80’s.
I think in general, though, the only companies that really made them were companies that made a lot of other 2-stroke engines. At the time, most of Suzuki’s smaller motorcycles were 2-strokes and IIRC the company that made Lawn Boys mostly made small outboard engines. 2-strokes generally aren’t great fits for lawnmowers because the weight savings aren’t especially relevant and mowers benefit from 4-stroke engine’s better low end torque.
Also, people don’t like to have to mix gas. Admittedly, some motorcycles (like some Suzukis, IIRC) had a mixing system so you could use regular gas, but for a mower, why bother with that on a lawnmower?
Not sure when they started converting lawnmowers and other small motors to 4-stroke; I suspect it came along at the same time as car pollution standards. A lot of little motors, chainsaws, lawnmowers, even some larger motorcycles in the 200cc to 400cc range used to be two-stroke. By the 1980’s it seems to me motorbikes were mostly 4-stroke; but maybe that’s just because I was using a bigger size of motorcycle.
Obviously the much simpler (and so lower maintenance) design was the appeal for small motors. IIRC they have a better power-to-weight ratio.
(When I was a tourist in Beijing a few years ago, I noticed a lot of electric scooters. They are trying to replace the heavily polluting two-stroke scooters with non-polluting ones. For good reasons )
2 stroke are more polluting and louder.
I remember one of the neighbors had a Lawnboy when I was a kid and it always smelled funny to me compared to our 4-stroke Briggs and Stratton.
When I was a teenager in the mid to late 70’s I worked as a small engine mechanic. Lawn-Boys were definitely considered high end. The deck was either aluminum or magnesium so quite light and never rusted. Once an old boy brought in a Lawn-Boy tiller to be ‘fixed’. It was basically just a box full of parts that had been in his garage for 20 years. We could still get the few parts that were missing so we cleaned it up, put it back together, fueled it, and it started on the 2nd pull.
And power per unit capacity too. Although a single power stroke is less efficient in a 2-stroke than a 4-stroke, getting power on every downstroke more than compensates, and certainly for many years - I don’t know if it’s still the case - four-stroke racing bikes got eaten alive by their two-stroke counterparts.
Bigger bikes generally have always been four-strokes, but certainly bikes like the Suzuki and Kawasaki 750cc triples were considered extremely hot in their day, and the Yamaha 350LC watercooled was reckoned able to keep up with most 750cc four-strokes.
I just sold my ten year old Lawn Boy mower. It ran fine, but the reason I wanted a new mower was to get a self propelled model. Maybe the weight savings doesn’t matter much now because people (like me) are getting lazy and don’t want a push mower. Also it left a nice cloud of blue smoke when starting.
^^ Who is this guy? :dubious:
The cloud of blue smoke when starting. And then you had to throttle it. A memory fragment from my childhood. Thx.
I had a '73 Kawasaki 350 S2 triple. At the time, it was an amazingly fast bike, probably to the point of being dangerous, especially given how light it was.
All true. The 2 stroke was simpler and revved faster. Pollution controls made the 2 stroke obsolete. At the time the fastest motorcycles were 2 strokes. The Daytona motorcycle race was dominated by Harley 650cc 4 strokes. Then Yamaha came along with a 350cc 2 stroke and just smoked them. No contest. That Kawasaki 3 cylinder was legendary. Wicked fast for a motorcycle at that time. It was maybe the first “crotch rocket”.
As I remember most lawn mowers were 2-stroke when I was a kid (1970’s). Note that nowadays small 2 strokes (lawn equipment, outboards, bikes) usually have to be direct injected to meet emissions standards. And emissions regs do exist for such small stuff, because at a certain point after car emissions declined markedly, even the tiny total horsepower-hours of still very dirty lawn equipment engines was adding a measurable amount to total pollution.
With direct injection, the main source of extra 2-stroke emissions, the gasoline laden air which goes into the exhaust after being blown through the cylinder in the scavenging process, is eliminated. And you don’t mix oil and gas but rather the lube oil is injected a little at a time and burned completely. But still, 4 stroke is more common now on small gasoline engines.
Yep. RZ collector, here. Flat stomps much larger bikes of its era. (early 80’s)
2-stroke bikes would still dominate (Supercross/Motocross and MotoGP) if they didn’t re-write the rules to basically exclude them. Light and fast. Just my opinion, however. I was at the Vegas race when Doug Henry won the first “new” 4-stroke Supercross against 2-strokes. (His was 450cc vs. 250cc) I kept the ticket stub and told girlfriend’s kid, “This is the beginning of a new era”.
The new 4-strokes have come a long way however in weight savings and power. The 450’s they race in Supercross are scary fast. They don’t so much mow the grass, they remove it!