Query of Changing Engine Oil Frequency

Hi,

Am I correct to say that a small cc bike engine is working harder than a big
cc bike engine for a same distance (eg: 10,000km)?

If the a above statement is correct, does it mean that the small cc bike has
to change its engine oil more frequently? Lets say a 400cc bike is changing
its engine oil every 5000km then a 125cc bike should change its engine oil
not more than 2500km?

 

Why would this be the case?

Why not just follow the manufacturer's suggested change interval?

 

Define your perspective. What does "working harder" mean?

Lets say your "little" bike has 1" bearing mains and turns 6,000 RPM
under "normal" conditions. And your land ark super SUV has 3" bearings
at 2,000 RPM. Guess what? The bearing velocities are exactly the same.

I haven't had a V8 apart in a while so I'll be the first to admit that
3" is a bit big for a consumer engine but not unrealistic in a
commercial Diesel truck engine.

Then considering most motorcycles have ball bearing crank mains, the
bearing contact velocities are much much less.

For a homework assignment try the same math on maximum piston speeds.


As for attempting to establish an all-encompassing generic
generalization, as others have already said, "Read your owner's manual."
The motorcycle manufacturer has a much better grasp as to what your
engine needs. Much better than even the oil manufacturer's marketing
department who only wants instill fear so you will readily purchase
greater quantities of their most expensive products.

My GL1800 gets an oil change every 4,000 miles or 12 months, whichever
comes first. Been riding the KTM dirtbike a lot so the GL sits more than
it used to. The KTM RFS gets oil change every 15 hours, which works out
to every 3 to 5 rides, or 3 to 5 washes, or 1 dirty air filter wash, or
about the same as valve adjustment interval. The KTM gets its oil
changed very often not because I'm worried about the oil wearing out but
because I'm worried about the dirt and water I expose the thing to.

 

Only if the smaller engine is being used twice as hard.

 

As Mark Olson says, this is complete nonsense - apart from two-strokes.

Ball race cranks haven't really been seen in four-strokes since Suzuki
killed the GS range and Kawasaki ended production of the
Z1/900/1000/1100 series.

I *think* one or two four-stroke singles have used built-up cranks, but
ICBA to Google.

 

That might be true of some older small bore engines of less
sophisticated designs. Drain your oil into a clean pan. If you're
seeing "crispy critters" in your oil pan when you change oil, go ahead
and reduce your oil change interval until you no longer see those
little black things...

The comparison is too general. Maybe the 400cc engine is an older air
cooled design with a longer stroke compared to its cylinder bore and
and the 125 cc engine is a modern watercooled design with a very stroke
stroke in comparison to its bore diameter...

So you need to follow the motorbike manufacturer's recommendations for
oil change intervals...

One thing that you should understand about oil is that lubricating oil
is separated from crude oil by a process of heat distillation. Since
the engine gets hot during operation, your petroleum-based oil
continues to distill and get thicker inside your engine...

You want your engine oil to reach 212 degrees F everytime you run your
engine, in order to boil off any water tht has condensed in the oil.
Water
in the oil combines with sulfur, making sulfuric acid that eats away at
the parts of your engine...

The maximum temperature that your petroleum oil should regularly reach
is
240 degrees F . If the oil never gets over 240 degrees, follow your
owner's manual for oil change interval based on time and mileage...

For every 10 degrees F over 240 degrees, you should *theoretically* cut
your oil change interval in half, according to the motorbike magazine
writers...

So, if your manufacturer recommends changing engine oil every 3500
miles, and your oil temperature gets up to 290 F, this theory suggests
you should change your oil every 109 miles...

There have been big bore Honda engines that regularly heated their oil
up to 315 degrees F in the cylinder head area. Theoretically, their oil
should have been changed every 40 miles or so, not that most owners
ever actually
did this regimen...

Actually, that 315 degrees F was just local heating, whatever light
fractions distilled out of the oil would leave waxy brown deposits or
asphaltic black goo up under the valve cover, while the rest of the oil
just got thicker and thicker and thicker and was more difficult to
circulate. What an observant rider might notice at his 3500 mile oil
change would be small black carbon particles in the oil. My friend used
to call them "crispy critters". That suggests the oil change interval
should be changed...

And the magazine which suggested halving the oil change interval for
every 10 degrees over 240 admitted that they just weren't seeing a lot
of smoking wrecks of motorcycles abandoned along the roadside, having
died of lubrication failure...

 

.... and eats away at the oil itself, reducing its lubricating properties ...

 

You are one ignorant loudmouth and know nothing of cranks aside from
being one. I have two current production 4 stroke bikes with roller
bearing cranks - a DRZ and an LC4.

You know nothing much, do you?

 

You really are an ignorant and objectionable twonk.

Did you read the line you snipped?

"I *think* one or two four-stroke singles have used built-up cranks, but
ICBA to Google."

Now remind me: what's an LC4? and what's a Suzuki DRZ? Oooh, hang about,
it's coming to me...

And if you read again the para you left unsnipped, it reads "Ball race
cranks haven't really been seen in four-strokes....". That's an
open-ended statement. It's not a definitive statement that they've never
been used since the 1970s.

Take those together and you'll see that I was, indeed, accurate and
David Kelly was, indeed, talking utter crap.

And yes, I almost certainly *do* know more than you.

 

And his two examples are singles, a class of bike which I said I
believed still do use b&r cranks from time to time.

No, let him stick around, and let's see what other idiocies he comes up
with. It's always fun watching people make fools of themselves.

<Taps fingers expectantly>

 

Because the asshole picked a fight with me in public. He's ignorant and
I will point it out when I see him. Where were you when he picked his
fight with me?

He can fry in hell for all I care.

 

Nope! Surprisingly orant, in fact.

Got it wrong, then didn't you, boi? Dearie dearie me.

Regarding you as a complete idiot?

Sizzle! Sizzle!

*Lovely* Thanks for that, Cassel, sweetie-pie. You've made my day.

 

Oi! I resemble that. There was no tiff as such IMHO that implies a
fairly even argumenbt or dispute, and I don't think there was anything
of the kind. And certainly no rancour on my part.

Amusement, maybe.... ;-))

It's the "in public" bit that makes me snigger. I mean, does he think
that Usenet is a private club or something?

 

<Slips MO a tenner>

 

"The Older Gentleman"
message

<takes tenner FROM MO and hands it back to TOG>

I'm sorry sir is there a problem? This person has
been standing around the front door all day taking
peoples monies. Rather sad really, pretending to
be the doorman we neither have nor need. 8^) The
waitstaff and members are quiet capable of sorting
who does and does not belong.

Now if you'll excuse me I'll get back to drinking
my last Sam Adams Lager of the holiday.
--
Keith Schiffner
RCOS #7
Assistant to the Assistant Undersecretary of the
Ministry of Silly Walks.
"terrorist organization" is a redundancy