ransley wrote:
On Dec 14, 6:33 pm, James Sweet wrote:
ransley wrote:
On Dec 14, 4:05 pm, E Z Peaces wrote:
Jay Chan wrote:
One additional question: The Tech Manual from John Deere asks me to
make sure the engine is running at 3600 rpm when the engine is set at
high-speed mode. I am under the impression that we don't want the
engine to spin too fast and burn itself. That's why we want to keep
its rpm to not more than a certain limit. This means I need a
tachometer. But tachometer seems to require seeing or touching the
spinning part of the tachometer in order to measure the rpm.
Unfortunately the engine is fully enclosed, and I cannot see the
spinning part of the engine. Is there any tachometer that doesn't
require seeing or touching the spinning part of the engine? Can we
measure the rpm by timing the number of sparks that the spark plug
makes?
Where grass wasn't heavy, I used to throttle my mower down to reduce
noise an save gas. Now my mower has only one speed.
I think manufacturers have found that engines that can't be run slow
have fewer warranty claims. Keeping the RPMs up can mean better
lubrication and cooling.
Slower running engines last longer and run cooler, single speed is
cheap to make. 3600 rpm is normal full speed, cut it in half and motor
life increases at least 4x. Long life engines run very slow.
And require greater displacement to produce a given horsepower. Like I
said, it all comes down to cost. People want cheap, and they want enough
power to cut their grass. These motors hardly ever wear out before the
equipment they power anyway, change the oil yearly which hardly anyone
ever does and a lawnmower engine can last 50 years.- Hide quoted text -

- Show quoted text -

An hour rating is better and its from maybe 350-2000 for a cheap
Honda, ive worn out a B&S that was well maintained in 350, and I have
an 83 Lawnboy thats great. 50 years, with a small lawn.


Yeah that sounds reasonable.

I figure most people mow their lawns about 15 times a year, although
obviously that depends on location. If a typical suburban lawn takes
roughly a half hour to mow, and 350 hours engine life is good for 46
years. Not saying nobody ever wears them out, but I've scrapped a number
of lawnmowers due to rusted out decks but the only motors I've ever
junked were ones somebody ran out of oil.