Getting top MPG
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Thread: Getting top MPG

  1. #1
    Member dmathia's Avatar
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    Here is a nice article on a 2008 XT250 in CleanMGP.com. It focuses on the fuel economy, they were getting 104MPG out of it.



    CleanMGP is a good resource for techniques on getting the most out of your tank of gas. Some of their ideas are more extreme than the typical rider would use, but the fundamentals are sound.



    Highlighting some of the basics:



    Speed Kills - it's also bad for your gas mileage. 40-45 is ideal. Mileage really drops over 55.



    Tire Pressure - CleanMPG recommends using the maximum pressure listed on the tire's sidewall.



    Gear Ratio - if you are worried about MPG, 14/42-45 or 15/45-50 gears will help.



    Engine Tune - clean air filter and carb, proper valve clearance, good spark plug, correct ignition and cam timing.



    Oil - keep it clean and light. Lots of threads on these forums about that. I won't get into it here.



    Gentle Acceleration - full throttle eats gas (duh).



    Avoid Engine Braking - conserve your momentum by using your clutch and coasting down when possible. Unlike fuel injection, carbs still feed gas when decelerating (more than at idle).



    Weight - not a lot we can do here, but extra bags, fuel and gear obviously pull down mileage. Only carry what you need.



    Time The Lights - try not to come to a complete stop. Slow down before the traffic light so you arrive when it turns green.



    Don't Idle Too Long - turn off the motor if idling >15 secs, when it is safe to do so.





    There are a lot of posts about re-jetting carbs. While most performance mods come at a cost to gas mileage, it's possible to

    actually get better mileage by having the proper mixture using conservative re-jetting if you are running too lean. Definitely adjust the idle mixture so that you can achieve a smooth, low idle.



    I found on my 2007 after adjusting the idle mixture, the factory jetting runs fine anywhere from sea level to over 9000 ft.

    I am consistently getting around 92MPG driving 50-55 carrying my 6'4" 225lbs, 75% highway 25% city using E10 premium in 90+ weather.

    Tires are 30 front and 32 rear for highway driving, gears are 14/45 with an O-ring chain.



    Comments and ridicule welcome.
    07 Tdub - Jimbo shield, Givi carrier, 14/45 gears, O-ring chain, Tusk guards and risers, big pegs, seat pad, 45oex tip, Ultra H4, LED rear lites, fuel filter, dual horns, foam grips, storage tube, AGM battery.

  2. #2
    Senior Member lizrdbrth's Avatar
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    No ridicule from here. All great info, particularly concerning the impact that jetting has on MPG.



    The only ridicule that I have concerning some of those sites (I'm a member of most of them. 61 mpg Metro) is with those who engage in hypermiling techniques as a daily commuting strategy. Rolling red lights and stop signs and becoming an obstacle on highways with a case of "Prius Owner Syndrome" as a daily strategy is just flat dangerous, (even more so on a bike) and often high end of the mileage scale reflects that type of behavior.



    I can explain it to you, but I can't understand it for you.

    Powdercoated '87 frame, extended swingarm, YZ fork legs, ATV tire, 14/55, XT350 tank, spliced quick-release seat, disc brake conversion, beeg headlight, beeger rack, Lizrdcooler, Lizrdventz and bunch of other stuff all covered in invisible ink.

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  3. #3
    Senior Member RodneyReed's Avatar
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    +1. Safety 1st, MPG 2nd.

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  5. #4
    Member dmathia's Avatar
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    Definitely, common sense tops max MPG. (no drafting 18 wheelers!)
    07 Tdub - Jimbo shield, Givi carrier, 14/45 gears, O-ring chain, Tusk guards and risers, big pegs, seat pad, 45oex tip, Ultra H4, LED rear lites, fuel filter, dual horns, foam grips, storage tube, AGM battery.

  6. #5
    Senior Member elime's Avatar
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    "Prius Owner Syndrome" -- now that is funny! I never knew it had a name but I see it all the time. Getting maximum mileage and holding up traffic and to hell with everyone else.



    At 66.5 mpg from my TW I am happy. 14/55 ratio and every stop sign is like a drag race. On a highway I am in the slow lane but at or near WOT.



    More power to you guys that get more mpg.





    Long live the internal combustion engine!

  7. #6
    Member birdmove's Avatar
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    There is a lot one can do as far as riding technique to maximize gas mileage. I had a 2007 Yamaha XT225 for some years, and , when kept to 50 mph and under and ridden easily (gradual accleration as opposed to full throttle) I could get over 100 mpg, and often did. I won't be shutting off a motorcycle at a stop unless it's a long stop due to road construction or an accident or something. First, with the engine shut off, you have no way to instantly take off should the idiot behind you accidently plow into you. Second, any mpg increase you might get by shutting off the bike is more than offset by starting system wear and tear in my opinion.Starters, starter clutches, relays, solenoids, etc.



    Jon
    Jon

    Keaau, Hawaii

  8. #7
    Banned qwerty's Avatar
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    Excessive tire pressure has a negative effect on handling and braking. Unacceptable safety issue. There is also a detrimental effect on tread wear and tire life, as much as 75% loss.



    A lean slightly lean mixture is good for efficiency, but bad for engine life due to the engine running hotter. Spark plugs don't last as long.



    Short shifting and lugging the engine at too low a RPM reduce oil pressure and can result in engine wear and battery charging problems. A reasonable acceleration allows higher gears quicker and savings in fuel over slower acceleration rates.



    Thinner engine oils are less parasitic on power. Too thin and engine life is reduced through increased wear. Combined with lean jetting and high temperature and siezure is possible.



    Tdub has returned 101 to 111mpg repeatedly with a slightly lean tune, 22psi front, 25psi rear, the maximum recommended in the owner manual. This efficiency came with 15/47 sprockets and a power-robbing o-ring chain running 10W40 dino oil and 87 octane gasoline with no ethanol, in-town among Saginaw, Northside, and Arlington in cold and dry winter weather. Routing focused on minimizing stops and slowdowns for traffic, lights, and stop signs, on roads with 40-50mph speed limits. Riding style was conservativally keeping up with traffic until the speed limit. The secondary road choice of routes was due to lacking sufficient gear for protection from cold at highway speeds.



    It is not necessary to jeapordize safety or be a hinderance to others on the road to see good fuel efficiency figures. Set your bike up correctly and go with the flow of traffic up to the speed limit on roads with limits of 50mph or less. Avoiding ethanol-laced fuels is a major contributer to efficiency.



    It is clearly evident that choices in vehicle tune and set-up are compromises. Maximizing efficiency is a laudable goal, as long as you don't make an ass of yourself.



    There was an incident in Memphis where a hypermiler rolled a stopsign, causing a motorcyclist to hit a median and crash. The hypermiler drove on. some of the folks riding with the motorcyclist got on the phone, chased the hypermilist down with video camera recording, followed until the police caught up, and filed the report, which included the motorcyclists whipping out a tire pressure gauge and having the officer note in the report that the tires on the car were over-inflated. The video allowed the investigating officer to ticket the hypermilist for several driving infractions, including running redlights and stopsigns, speed excessive for the conditions (tires squeeling around corners), tailgating, and other stuff I can't remember. With the tire pressure data, the video of the hypermiling driving style, and the hypermiler's hypermiling blog as evidence, the motorcyclist was able to collect not only for the actual damages to his bike and gear vand medical expenses, but also compensatory damages for pain and suffering, mental anguish, lost income from missing work while recuperating, etc., and punitive damages for reckless endangerment. Yes, hypermiling is reckless endangerment. Be careful.



    "Prius Owner Syndrome" P.O.S. Well, fits pretty well with the Prius owners I know.




  9. #8
    Member dmathia's Avatar
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    @jon

    I appreciate your concern for safety, but I think you are too worried. In my sixty years, I have been rear ended once, and he hit the car behind me and pushed him into me. I never saw it coming.



    When I am stopped at a light I know is not going to change for a couple of minutes, I am usually behind someone and someone is behind me. Very rarely am I stopped at a long light and I am the only vehicle waiting. That would be the only scenario in which you are talking. I would like to hear from anyone who was fortunate enough to be watching their mirrors constantly while waiting for a light, to notice someone about to hit them from behind, and to be quick enough to pull away.



    As far as wear and tear, my Tdub starts instantly when the starter hits. Not much wear happening the 3 or 4 lights I do that on my 50+ mile round trip to town. Also, particularly in Florida (or anywhere hot), idling a hot engine where it is over 100 degrees on the asphalt could stress an air cooled engine. Maybe Mr Gizmo could tells us if that is a problem, he has a temp gauge on his.

    But realistically the difference is mileage is minor. It's just a suggestion.



    @Qwerty

    Your experience and advice is outstanding. I agree with you about not going over the sidewall max inflation. Do so at your own risk.

    I deleted that reference.



    The pressures I use are just below the 33 max rating of the stock Bridgestones. They are also rated to carry over 900 lbs at that pressure! These big tires are why we love our TW's.



    I disagree with any concern about increasing tires to their sidewall recommended max. First, where to you get the 75% wear figure? I have been a mechanic all my life and have never encountered that kind of wear from running a reasonable amount over the door sticker. If anything, it should decrease your tire wear.



    Unacceptable safety issue? Not according to Wikipedia: High performance and dynamic drivers often increase the tire pressure to near the maximum pressure as printed on the sidewall. This is done to sacrifice comfort for performance and safety.



    Vehicle manufacturers set tire recommendations to the LOWEST possible number. Why? Because there is no disagreement that raising the pressure increases road noise and ride harshness. No manufacturer wants to have their vehicle branded as noisy and harsh. Tire manufacturers (and their lawyers) also use a conservative figure for their max tire pressure. It's nowhere near the real max capacity of the tire. That's the premise CleanMPG uses in hinting at using even higher pressures.



    I have run tires on my car for 40,000 miles set at the sidewall max. No center wear at all.



    It is far worse to run your tires under-inflated. Tread temps increase, more danger to rolling off the rim, more danger with being pinched by the rim, etc.



    Otherwise, we are in agreement. I would love to find a gas station here that doesn't sell gasohol and to find a highway to town I could do 40 MPH. I can't wait to Fall when temps drop below 90. I want to see that 100MPG number!
    07 Tdub - Jimbo shield, Givi carrier, 14/45 gears, O-ring chain, Tusk guards and risers, big pegs, seat pad, 45oex tip, Ultra H4, LED rear lites, fuel filter, dual horns, foam grips, storage tube, AGM battery.

  10. #9
    Banned qwerty's Avatar
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    Over-inflated tires are prone to rupture when hitting potholes and objects in the road. This type damage often results in catastrophic failure, with the tire coming apart and beating the vehicle with tread and belts, and sometimes even sections of sidewall. Over-inflated tires are also more likely to puncture due to lowered ability to conform to road debris, such as a pebble. Pebble? Yup. Seen it happen on mpg competition vehicles.



    Over-inflating a tire to stiffen it up for performance compromise ride, noise, and the tire's ability to resist damage, none of which are an issue on the track. Slightly wider rims are used with such high pressures to allow even contact pressure across the width of the tread. Over-inflating a tire on a wheel sized for street use will result in uneven contact pressure and a reduction of the traction available. Been there, done that.



    Tire pressure measurement is only currently accurate. There are many variables that affect tire pressure. On that note, be careful running cold pressures near the tire's max. A tire can gain several psi just from increases in ambient air temps--top off the tire in the cool of the morning and the pressure will be significantly higher in the mid-afternoon just from heat. Thermal expansion and contraction will be about 1psi per 10*F. Solar radiation can also warm a tire, causing excessive pressure, again, about 1psi for every 10*F change in the temperature of the air inside a tire. So can a change in barometric pressure, either from a weather front or a change in altitude. About 1psi for every 200 feet change in altitude. Even the load in a vehicle affects tire pressure because the additional weight pushes harder on the tire. Add 2 or 3 of these variables together, and tire pressure can go up by 10-15psi before the engine is even started.



    Once driving, a tire set at say, 36psi in the cool of morning (70*F) driven home in mid-afternoon on a sun-baked expressway (130*F, 6psi increase) along with the 5psi gain from flexure will be rolling along at 47psi. Take a trip from Fort Worth TX to Leadville CO, over 10,000 feet change in altitude, and PSI goes up another 5. The tire is running at 51psi. Not at all uncommon real-world figures.



    Knowing these variables is why tire engineers design a bit of extra capacity into tires. A user knowing these variables can safely make use of that bit of extra capacity, with a little thought and care, but a moment of carelessness can result in disaster.



    More infor on tire pressures here. Lots of good articles on tire care and use.



    By the way, it is easy to take the ethanol out of gasohol. Simply add water and stir. At 10% ethanol content, you'll lose about 3 octane, so either start with 90+ or replace the ethanol with the same amount by volume of toluene to restore the octane. I have a big steel funnel with the top welded to a 5-gallon gas can and the bottom welded to a pipe reducer and a hose nipple, with about a foot of clear fuel line and a valve, then another foot of fuel line to direct the drain into various containers. Simply dump gas in the tank, add a measured amount of water, and stir. Wait an hour, come back, and the water and ethanol are the clear layer at the bottom of the contraption. Simply open the valve in the fuel line and drain the water and alcohol into a garden sprayer for killing weeds--good stuff for doing that. As soon as the yellow appears in the fuel line, that's gasoline, less alcohol. Deduct the volume of water you original added from the volume in the garden sprayer to calculate the volume of ethanol removed from the gasohol. Add a volume of toluene equal to the volume of ethanol to the gasoline to restore the original octane rating.



    Toluene, aslo called toluol, is a common paint thinner so it's easy to get. Toluene was a common octane booster in the pre-gooberment reg era, sometimes used in proportions up to 50%. Formula 1 cars used to run diluted toluene as fuel--the toluene was rated too high an octane to be allowed straight, so it was diluted with a low-octane substance to meet the limits of the rules.



    I expect you gain nothing by running octane too much higher than 87. Dyno results with Tdub with stock jetting show a loss of power at 91 octane with E0 and 89 octane with E10. When properly jetted with E0 fuel, power loss begins with 89 octane. I expect since you are already wasting money on premium E10, you can wash out the ethanol and use the base gasoline as is. Cheaper way to real gas over mixing toluene. I expect you'll gain 2-2.5% improvement in MPG for every 1% of fuel that is alcohol you remove. That will go a long way towards your fuel efficiency goals, and I expect will cut your $$/mile a bit at the same time. Well, probably not, because the engine will run so much better you'll have a hard time resisting the temptation to play with the throttle.




  11. #10
    Senior Member lizrdbrth's Avatar
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    91 is nothing to sneeze at. I'd be pretty dazzled with that figure as an average. But I also realize how devoted and geeky one can become to squeezing out that extra mile. It's as infectious and satisfying as squeezing out horsepower, and generally speaking it's a helluva lot cheaper hobby as well.



    The XT would be a better candidate, but if a TW were a better starting point than it is I've been really tempted to build one not so much for mpg but to increase sustainable highway speeds. I'd like to do a few Iron Butts on one just to prove a geeky point, but a lot of the same techniques would meet both ends. To be a real candidate for either the first thing that would have to be discarded on a TW would have to be the rear rim and tire. Then it's just aero, tuning, tires.



    I think the safer approach to the tire issue is downsizing. At low horsepower levels I wouild think less rotational mass would probably be a safer split between safety and mileage than would excess pressures. This became all to obvious when I put the ATV tire in my TW.



    I can explain it to you, but I can't understand it for you.

    Powdercoated '87 frame, extended swingarm, YZ fork legs, ATV tire, 14/55, XT350 tank, spliced quick-release seat, disc brake conversion, beeg headlight, beeger rack, Lizrdcooler, Lizrdventz and bunch of other stuff all covered in invisible ink.

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