Author Topic: mpg revisited (Read 4868 times)

Squirrelciv · « **Reply #20 on:** March 15, 2011, 21:44:14 »

OK, so I'm running in the engine and riding like a poof, but... 68MPG!!

Happy me.

mr_diver · « **Reply #21 on:** March 15, 2011, 22:37:48 »

OK, I'm no slouch, or the doctor, but I'm getting around 58-62mpg, mostly on local roads and a bit of duel on my run to work.
was getting nearer 70 when I first had the bike, but too nervous to use the gas as just came from a 125cc.
I'll happily trade off a bit of mpg for a little thrill on my commute!

Sven · « **Reply #22 on:** March 15, 2011, 22:48:29 »

Quote from: "Jammo"

I've been logging my fill ups on fuelly since day 1, it's a freebie site... You can see my results by the link below...
(Make sure that UK is selected at top left of the website link - tends to default to US)

http://www.fuelly.com/driver/vstrom/DL650

That's a great site. Some very interesting info on there.

Juvecu · « **Reply #23 on:** March 16, 2011, 10:56:36 »

Hmm, I might need to consider changing to a new twin plug Wee then, that's a significant difference from the 52 I'm getting. I think it will be a Burnt Orange one

I'll probably have to keep the current Wee for at least another year or 2 before changing though.

Gassoon · « **Reply #24 on:** March 16, 2011, 11:29:48 »

You sure your current one will last that long, juvecu? Have you extrapolated what mileage you might have done by then?! I'm getting 54 mpg out of my 08 wee BTW. Very mixed riding. The colour possibly helps

Hookie, you just brought to mind my first bike - a Honda C50, step-through automatic clutch, 4-stroke, bought it from my dads mate for 5 quid in 1971 (circa). The tank was under the Seat,, when I was old enough (still at school) I got 120 mpg out of it, I recall and it held less than a gallon, I think!
Later, my triumph T120T got 80+ mpg fairly consistently, and a T140V used to never drop below 50+ mpg.
My worst bike for mpg was my yamaha XJ650 - but at that time I rode more mentally, and the engine begged to be thrashed.
Once borrowed a mates Suzuki 500GT (2-stroke) for a trip to Birmingham - ran out of fuel after about 20 miles, filled up on motorway, ran out about 50 miles further on (really pushing it!) I think It worked out less than 20 mpg, until I slowed right down!
Err, didn't mean to ramble!

hookie · « **Reply #25 on:** March 16, 2011, 11:47:51 »

Your C50 was the much later overhead cam model and was arguably less economical and reliable than the old push rod one. I used to service the original Kawasaki 2 strokes- A1, A7, H1, H2 and so on and it was quite easy to get the 750 triple down to 15mpg giving it a bit of stick. Great fun and when you got home you felt you'd actually achieved something as you'd made it without chucking it up the road! Happy days eh....?

Juvecu · « **Reply #26 on:** March 16, 2011, 11:55:25 »

I've worked it out as about 42k miles per year. So in a year's time it will be near 100k. I figured I might keep it until it falls apart, but that might take forever. Initially I thought I'd sell it at 100k, but then I moved to Warwick and the miles started piling up, now I'm thinking 200k, but if it gets there and it's still going strong I might consider using it as as bits for a project (one yet to be dreamt up.) I guess I'll see when I get there, I might just strip it, powder coat the frame and rebuild the engine, maybe I'll respray it yellow/orange

Strommer · « **Reply #27 on:** March 16, 2011, 13:10:47 »

K5 - 55mpg. 60mpg on the motorway. Mixed urban.suburban riding with some 70mph A-road. Smooth I am not...

Juvecu · « **Reply #28 on:** March 16, 2011, 13:22:35 »

Strommer, when you are on the motorway, what speed do you go at (indicated)? Do you still have the standard exhaust on?

Strommer · « **Reply #29 on:** March 16, 2011, 19:15:57 »

Generally I'll sit at about 80 indicated (72 GPS). That's at summer temp - seems to dip to 55 mpg-ish in winter.

islandtiger · « **Reply #30 on:** March 16, 2011, 21:01:44 »

Do I wish I had a Wee for mpg--no way I could have had a fizzy 50 but never had
vee for me even though my mpg is well down in the 30's--it is fun though

beep · « **Reply #31 on:** March 17, 2011, 09:32:27 »

I get 55-60mpg, on mainly B-roads, which sounds very typical for a Wee.

Juvecu · « **Reply #32 on:** March 17, 2011, 10:44:59 »

That's the same speed I sit at and at present I get about 52mpg, it's still cold though. I'll watch it during the warmer months, maybe it's not so bad after all. I also have a smaller screen on now and it looks like it's creeping up a bit.

Strommer · « **Reply #33 on:** March 17, 2011, 12:09:52 »

Still not sure why it's worse in winter though I'm inclined to dismiss the engine related arguments and suggest it's:

- heated grips
- more headwinds
- more sidewinds (a wobbly ride is a longer ride)
- heavier clothing
- clumsier throttle action (big gloves)
- poorer aerodynamics due to bigger clothes
- less constant riding style (bigger clothes reduce the sensation a bit and lead to heavier throtle action)

Juvecu · « **Reply #34 on:** March 17, 2011, 12:56:40 »

It's colder in winter and the cold air has less pressure (Boyle's Law, thanks Fatbelly

) Less air pressure means less air is going into the cylinders which translates to less oxygen to burn. Less oxygen means more fuel needed. At least this is how I understand it. Makes sense?

jonH · « **Reply #35 on:** March 17, 2011, 13:09:58 »

Boyle's Law deals with gas in a closed system and relates to the pressure and volume of said gas - double the pressure, half the volume.

The relationship between temperature and air density is far more relevant IMHO and colder air is generally more dense, given a constant altitude. (Charles's law)

Juvecu · « **Reply #36 on:** March 17, 2011, 13:15:06 »

Not really my subject, but the missus is a chemical engineer and she might have an answer. I always thought that cold air would cause the engine to need more fuel to burn the same level as if the air was warmer. So I mean some of the heat is being used to heat the air as well during the ignition. The colder air would need to use more heat energy to than warmer air would need to expand the same amount. I'm not sure I'm succeeding in explaining the idea properly and I might be completely wrong too

jonH · « **Reply #37 on:** March 17, 2011, 13:40:17 »

to be honest the differences are probably negligible either way

steve_icbinb · « **Reply #38 on:** March 17, 2011, 15:01:34 »

K8 (twin spark) did 70.5mpg over 1000 miles around le Massif Central last year - just pootling around. can't touch that with my K5.
Next month I'm off to AssenWSB witth me bro (K5). It'll pee him off at the petrol pumps when I consistantly use less with the K8. He used to gloat so much when we ride K5's side by side that he got higher MPG...

Silly mpg is possible out of my 125 cub (Innova) - over 120mpg if I wanted!

Be interesting to see what we (DC, others & me) get out of our twist n go's next year on our planned Turkey and Bust mission...

Strommer · « **Reply #39 on:** March 17, 2011, 16:41:04 »

Quote from: "jonH"

to be honest the differences are probably negligible either way

That's my suspicion....