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Oil and economy

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muttley1
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Oil and economy

Post by muttley1 on Mon 08 Jun 2015, 8:53 pm

Hi,
following on from the very interesting thread here http://www.cb500club.net/t3708-trialling-two-controversial-maintenance-practices
I run two cb500's. One I've had for 12 years and its always had oil and filter every 3k, usually Hein Gericke semi synthetic 10w 40 and their filter. It does 52mpg and feels very responsive. This is a '98 bike (disc rear brake).

The other I've had for 2 1/2 years and its also had oil and filter regularly, every 2.5k according to the prev owner. However, this bike has had Silkolene synthetic 10w 30 and Honda filters. It does a surprising 61mpg and seems a little more docile than my main bike. This ones '95, drum rear.

Both have race cans, correct jets, balanced carbs and get ridden on the same sort of roads.

So, 10w 30 - seems to make sense? I think its what Honda recommend iirc?

muttley1
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ceejay
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Re: Oil and economy

Post by ceejay on Mon 08 Jun 2015, 9:05 pm

Interesting but for me there are so many variables involved here would be almost impossible to attribute that difference to the difference between those oils. I put 10w 40 motul semi in mine and get around 60mpg fwiw.
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wornsprokets
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Re: Oil and economy

Post by wornsprokets on Mon 08 Jun 2015, 9:33 pm

Yes its not down to oil or filters, early fireblades had somthing simular but wasnt mpg:)  its caused by running in period , some fireblades were trashed from new and others were run in correctly  the ones trashed from new had more power by 5 to 8 hp   , i am not suggesting to do this as u could blow new engine , thats what was said ?
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ashcroc
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Re: Oil and economy

Post by ashcroc on Mon 08 Jun 2015, 10:28 pm

When I was a kid my mum had a new car that finished it's run in on a trip down to the south of Germany. It definitely benefitted to being gently taken up though the revs & crused at 100+mph.

I've seen the other side of the coin too with a car that had never been taken above 40mph on trips to the shops & was sluggish as hell. Both fuel economy & responsiveness improved after it had been run in properly even though it was a few years old.


muttley1
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Re: Oil and economy

Post by muttley1 on Tue 09 Jun 2015, 12:27 am

Could be to do with the running in then.

I've had my main bike since 3k and its been used to the full as Mr Honda intended.

The other I believe came from and old chap who put the first 8k on it over 10+ years, then the Silkolene 4 years; 30k including track days and a european tour, and then me, 3k.

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stormbringer
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Re: Oil and economy

Post by stormbringer on Tue 09 Jun 2015, 6:47 am

@muttley1 wrote:I run two cb500's.
Both have race cans, correct jets, balanced carbs and get ridden on the same sort of roads.
One reason for the difference in mpg could be the oil. Run-in-period use could be another - which is hard to verify, because few people buy two identical bikes and use them for the same purpose. All we can do is try to shed light on the subject like you do. Thus, I'll read along with interest!

For information (not reference, too many variables differ) mine does 59 mpg (carefully measured over the course of +20.000 miles), is correctly jetted, uses Castrol Power1 10W40 & has Fuel can.

Q: Drag is responsible for a fair part of your petrol use. Do both your bikes have similar mirrors, shrouds and other drag-generating doodads? I'm asking because I've recently got a new helmet - and this seems to register on my economy-calculations. Which has led to me doing experiments with avoiding eg jeans (yes, kevlar, not the type from GAP) flapping in the wind. Best of both worlds; better comfort & better economy Smile

muttley1
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Re: Oil and economy

Post by muttley1 on Tue 09 Jun 2015, 1:29 pm

Hi,
and as I run basically identical bikes its still a surprising difference, could be the oil, could be the running in...

Stormbringer, good point ref the drag, it is another major variable and the bikes have differences in that respect. The 52mpg bike has a givi roadstar screen, its headlight mounted and pretty good, if tall. The bike usually has a large topbox on too. The 61mpg bike has a faabri screen, the standard sort of headlight screen and has a smaller 1 helmet only tobpbox.

Mirrors are Honda's finest, the 61mpg bike has renthal bars, wider and a bit taller than stock, the 52mpg one renthals too, lower and a bit wider than stock.

If I was to do any experimenting it'd be roadstar screen off and rearsets on, see how that goes...

muttley1
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jchesshyre
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Re: Oil and economy

Post by jchesshyre on Thu 11 Jun 2015, 11:20 am

Sounds stupid but are they on the same pilot mixture settings? I know that on CV carbs the pilot mixture affects a lot more than just the idle. But 9mpg? Hmm...

As a side note, I'm always amazed to read of anyone getting 60 or more mpg. My bike ('97 disc brake, stock except Fuel exhaust with baffle in place) is in very good tune (not perfect but I'm getting there) and even on a long run I get about 56mpg, switching to reserve at 200 – 210 miles. My previous '96 drum brake CB, with the same exhaust, was more or less identical. That's when I ride as I usually do - not caning it and trying to minimise braking and WOT but also getting a damn move on with plenty of overtakes. I guess if I was content to stay with the flow of cars, or go on motorways, I might get lower consumption.

muttley1, when you say 'same sort of roads' what sort of roads is this, and how do you ride?

muttley1
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Re: Oil and economy

Post by muttley1 on Thu 11 Jun 2015, 1:19 pm

HI,
no idea ref the carbs, only that both bikes run micron endcans and are jetted to suit.

Roads I ride are - a roads, 50 mile round trips, occasional 110 mile round trip, weekends: b roads and worse. Style of riding: experienced rider, I tend to make good progress Very Happy

muttley1
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Re: Oil and economy

Post by muttley1 on Thu 11 Jun 2015, 9:54 pm

Done some googling about the drag thing and its a bit confusing. Seems a screen can indeed break up the flow of air towards the rider but cause some disruption to the aerodynamics behind the rider "pulling" the bike back due to the turbulence created. This varies due to the angle and  height of the screen.
This also applies to topboxes, the turbulence created behind the rider then gets a further disruption due to the mass of the box and drags the bike.

Not rocket science ref topboxes but screens don't seem to = fuel economy from an aerodynamic point of view.

Still a little mystery ref my bikes though

muttley1
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HomeBrew
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Re: Oil and economy

Post by HomeBrew on Sun 14 Jun 2015, 8:01 am

I use 10w30 or 5w30 fully synthetic, the bikes seems to prefer it to the thicker stuff. I have a two helmet topbox 47 litre, I'm sure it makes alot of drag. Sometimes my helmet lifts up if the strap isn't done up tight when I'm going fast, alot of drag there.
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eternally_troubled
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Re: Oil and economy

Post by eternally_troubled on Sun 14 Jun 2015, 5:13 pm

@muttley1 wrote:Done some googling about the drag thing and its a bit confusing.

You can say that again!

It's very hard to predict what effects drag - it's not always the things you might expect.  This is why F1 teams and car/bike manufacturers spend lots of time in wind tunnels...

muttley1
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Re: Oil and economy

Post by muttley1 on Sun 14 Jun 2015, 11:35 pm

Good point ref helmets, windblast lifting them can't be a good thing.

Yes eternally, the turbulence behind the rider seems to be the thing, not so much any screen/fairing and the front end generally. So top boxes, mounting plates, grabrails, stick out indicators etc are all very bad news from a drag aspect (and perhaps a handling one too).

I would think that big mirrors and wide bars don't help either as the turbulence they set up will affect the bike too. One article reckoned that the radiator caused 7% drag due to its shape...it all gets a bit nerdy and theoretical and still didn't explain the differences on my bikes.

Time to just ride, imo

muttley1

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