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Discussion in 'Thumpers' started by neepuk, Jan 10, 2009.
"]Lotta downhills[/QUOTE] not serious
I do not know how you could get 95 mpg.
Ridden very gently at lower speeds I could get 85 maybe. At sea level.
Don’t know myself, and not really happy with it . The bike is bone stock ,carb never been touched . I plan to raise the needle and see if that helps. My other TW is getting about 70 mpg , which is more like what it should be for where I’m riding.
95 MPG and your're "not really happy with it"? Why would anyone not be happy with 95 MPG?
Either the original claim was a typo and he meant to type 45 or he was being sarcastic. At Colorado altitudes, I'd expect pretty good mileage.
Because it means the mixture is very lean and can do ugly things to the top end.
This is a myth - not really applicable to modern four-strokes. If it's running ok with no lean misfire and no pinging, it's just fine.
Modern four strokes . That’s funny stuff right there !
Thinking about properly designed squish clearance, reasonable control over exhaust valve temp., modern materials, etc. OK we don't have water cooling but in other respects the TW engine should not be especially vulnerable to lean mixtures. If it runs ok, it is fine. Also, unless the jetting has been leaned for altitude, the TW will run slightly richer at higher elevations (mostly compensated by the CV carb), making it even less of a concern in Colorado.
I am not sure I would call the TW motor modern!
But I wonder if there are or could be any changes in the parts since it was first sold.
I tend to doubt it.
As you go up, I would think the mixture would get richer and MPG would go down.
Riding the TW hard off road seemed to give about 60 to 70 mpg at sea level.
Riding it gently at 40 to 45 mph in 5th gear with no wide throttle openings might give 85 mpg but I could never do it long enough to measure it.
On the street, with lots of air in the tires, you should be able to get to 95 mpg if you did 40 mph in 5th gear I guess.
That is a lot of level gentle riding...
The mixture DOES get richer as you gain altitude but with a CV carburetor it is mostly compensated for. The idle mixture will be richer for sure. When I did the TAT on my DR350 (also a CV carb), I had to turn the idle speed up slightly when above about 10,000 feet. However, air resistance is reduced and fuel mileage will increase. More so with well set-up FI but you'll see it with a CV carb too.
At 10,000 feet the air is so thin a TW will struggle to hit 40mph in 5th gear so yes, 95mpg may be possible
When I run my TW with a 16 tooth front - 47 tooth rear sprocket, TW203/204 tires, FMF exhaust and a 130 main jet I get around 80 miles per gallon under 1000 ft elevation on road. I'm sorry but I have a very hard time believing 95 MPG under the conditions described. Maybe 95 KM or some miscalculation?
I know it seems hard to believe, so let me throw some gas on this fire and tell you my best mileage has been 102 mpg , that was all at elevation above 2000 ft. . So if I was to ride at sea level the bike would be even leaner .
If memory serves me well. I remember a member on the old TW forum that rode his under 30-35 mph (scooter speeds) for a tank and got 130+/- mpg's.
The TW can get great mpg's. Most riders can not. Ymmv
There seems to be an assumption here that running an engine lean results in better fuel economy - not necessarily true. An engine gets its best economy when it is running efficiently. With an engine running too lean you must work the throttle more and push the engine more to get the same results you can get at less throttle with a properly tuned engine. This is my experience. My engine ran smoother and more efficiently after I corrected the lean settings from the factory.
Am I the only one who has never checked mpg?
Although all this talk may motivate me to find out.
Same here. My old TW doesn't have a trip meter and I never remember what it was at on the last fill up.
Not intending to check the mileage on a ride a couple of weekends ago, I was just surprised I had gone so far on a stock tank before switching to reserve. It was something like 110 miles. When we got close to home I dropped into the gas station to fill up. I can't remember my final mileage, I think about 127 and it took 1.5 gallons of gas. I think it was something like 84 mpg. All my other TW's have larger tanks and I've never checked fuel mileage nor do I go on reserve with those tanks. My butt gets too sore to ride that far I think.
I'm not generally OCD but I do track mileage pretty closely on most of my vehicles. Have not put enough miles on the TW to have a clue but I have a spreadsheet history for all my other bikes. Will be interesting to (finally) get the TW on the road and see what it can do.
A new TW contest!
Who can get the highest mpg?