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Author Topic: M90 Engine Displacement QuestionHi  (Read 290 times)

70Rcode

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M90 Engine Displacement QuestionHi
« on: February 19, 2020, 09:34:57 am »
Hi all, ...Looking at my M90 instruction sheet specs (and my digital calipers) the Cylinder Diameter at 22mm & an  Itinerary (Stroke ??) of 20mm for a Displacement 6cc. ??  I keep computing 7.6cc Displacement size..What an i doing wrong ?...i was on a "i got this easy calculation" roll until i "faceplanted" on the Itinerary parameter. Thx for any help, ..tom.

Raphael

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Re: M90 Engine Displacement QuestionHi
« Reply #1 on: February 19, 2020, 12:04:33 pm »
Bonjour Tom,
Based on your figures, I also obtain 7,6 cm3...  ;)
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70Rcode

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Re: M90 Engine Displacement QuestionHi
« Reply #2 on: February 20, 2020, 02:53:36 pm »
duh !!
after seeing my post, the obvious slugged me ! ... the leading "7" probably got lost ....of course it's 7.6cc !! ...still the M90 newbie who sometimes gets crossed up in mm's, cc's & L's...tom.

Bentwings

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Re: M90 Engine Displacement QuestionHi
« Reply #3 on: March 22, 2022, 03:23:46 pm »
The formula is bore radius squared time stroke time number of cylinders if you have double acting you can double the number of cylinders as you are going both ways. With power.

Adirondack Jack

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Re: M90 Engine Displacement QuestionHi
« Reply #4 on: March 25, 2022, 09:13:02 am »
The Chinese native speaker translating to English does seem to have frequent issues with expressing numbers.  I just went through this where they butchered fuel/oil ratios, mistakenly translating 40:1 as 25%.  The obvious error of a 25% oil mix was easy to spot.  Those numbers not so intuitive to “eyeball” are the ones I’d be concerned with.  More mature companies hire technical writers/translators for exactly these kinds of things. It’s the smaller outfits that think they can’t afford such writers, until they realize they can’t afford not to.  Anyone who has ever suffered through off brand furniture assembly wishes for IKEA, and maybe appreciates why they’re pricier than Walmart standard….

Many moons ago, a professor assigned a technical writing class the task of writing instructions for unboxing and using a toaster, writing for someone transported from another planet.  It’s tougher than you might think.  Master that, try instructions for tying shoes for someone unfamiliar with shoes.  It’s 27 steps.