[theycallmeebryan]

Tank ending on 08-10-09: 90.13mpg

Tank ending on 08-16-09: 90.12mpg

I'm sorry that i have not posted in a 2 weeks or so. I have been quite busy enjoying life .

The past two weeks, i installed a radiator block about 75% just to see how it would affect my mileage. The cooling system works really well on my bike, and usually hovers just over the bottom normal temp line (about 25% of the gauge sweep), even in 70+ weather. With the radiator block, the temp operates around 50% on the gauge now, even in 95*F weather.

In essence, a warmer operating temp should richen the bike up a little, and it seems to have done just that as shown by the two tanks above. This makes me wonder whether or not the stock jetting is too rich for the summer temperatures, and whether i could gain another 5% or so by rejetting the bike. The only thing holding me back is that removing the carbs on this bike is a pain in the butt with the stock airbox still installed.

I'll never really know until i start messing around with different jetting, or until I weld a bung in my exhaust and hook my wideband up to it.

Originally Posted by The Atomic Ass

These were not available the last time I checked for my 250, and I doubt they've come out with them in the last 2-3 years. The 250 uses 16" narrow tires, 100-90-16 and 130-90-16, which severely limits tire choices, as no other bike I am aware of uses these size tires.

I use Kenda K671 Cruiser tires on my bike; 100-90-16's in the front and 130-90-16's in the rear. I usually run around 60psi in them without any problems. They are great tires for a tourer, handle really well in all conditions, and seem to last a long time. Motorcycle Parts, Motorcycle Accessories – BikeBandit.com always has them in stock when i need them, and they are around 50$ each. They are an all-around good value.

Originally Posted by greg123

Great result but I'm not too sure that simply driving really slowly counts too much. As in I can beat that figure by simply pushing the bike, or going on a bicycle. IMHO it's blasting around at normal speeds WHILE getting better economy than all the others around you which makes one an ecomodder, rather than just a slow driver.

Good stuff for cracking 100mpg though, they used to drive like that in the war to eek petrol out!

Greg.

Around town, I would say that i ride normally for the most part. For example, as you would expect to do on a sporty motorcycle, I take some corners aggressively, primarily to maintain my momentum. I do practice the usual ecomodder techniques of watching 5 cars infront of you and judging traffic and your speed accordingly for max efficiency. I never ever exceed the posted speed limit because there simply is no reason to do so. It is, after all, a speed LIMIT, not a suggestion .

On the highway i will not exceed 55mph because i found that to be the sweet spot as far as fuel economy, my bike's power at that rpm, amount of air I'm pushing through, and safety around other drivers goes. Most people dont mind me traveling 5-10mph under the limit on the highway. There have been some instances, but in the end who's paying for the gasoline that I'm using?

Bryan,

I read your post with great interest!!

I have an old VF500 Interceptor that I ride to work each day. I also stay in the crouched position behind a full fairing for almost 50 minutes on the way to work. You mentioned back pain, I don't have any at all. When crouched, I rest my elbows on top of my knees, which then removes most of the load on the back muscles. Very comfortable.

I noticed several posts were trying to lean the carb jetting to get better fuel milage. Historically, unless your jetting is slightly rich, this will not work, and may cause an increase in fuel consumption. Take a close look at the Craig Vetter website, and read the detailed accounts of how other motorcyclists got close to 500 mpg on small displacement gas engines.

You will note that any fuel mixture changes from stock typically did nothing or reduced the gas milage slightly.

Bryan, you are definitely on track with the gearing. Charlie Perentian did two things to get over 300 mpg quite easily:

1) lower the engine rpm's with gearing changes
2) add a tear dropped fairing to the motorcycle

All this was done from years 1980 to 1985, during the Craig Vetter High Mileage Contest, right after the first fuel crisis. Dig around the web, and you will find more information about this. Great reading.

Keep experimenting!! I like reading your post.

Best of luck, Jim.

Thanks for the comments Jim! Those vf500's are pretty neat, 4 125cc cylinders in a V. Thing must be a blast to ride!

The reason i experience back pain is mainly because of where the foot pegs are positioned, and how squished i have to get to tuck. During my tuck, my knees are pretty high, probably 4-6 inches from my chest. I rest my helmet on my handlebar mounts and my elbows are pointed downward, arms laying on the sides of my legs. I was able to sustain the position for a long time, but after awhile + 16 years of being a goalkeeper in soccer, it started hurting me. Maybe if i was able to move the foot pegs down a good 2-4 inches, it would make things more comfortable.

I'm pretty sure my current gearing setup is about the lowest i can go right now, at least until i decide to make a full aero'd and tailed fairing for the bike. I have already done some extensive CFD work and am working on a good virtual design for the fairing. If i go ahead and decide to make a fairing, i want to have most of the guess work out of the way.

Originally Posted by MetroMPG

Just out of curiosity, do you consider 55 mph to be "really slow"? That seems to be the cruising speed that theycallmebryan aims for in his commuting on the 250 - at which he's getting these impressive MPG numbers.

Maybe I'm misreading your comment.

(Or maybe I missed some other post in this thread about theycallmebryan's typical speeds.)

Correct sir. On the highway, I aim for a throttle position that allows me 55mph on flat terrain with minimal head wind. I maintain that throttle position the entire highway trip, and allow the bike to accel down hills and decel up hills. For safety reasons, i tend to not let the bike drop below 50mph on the highway unless there is noone behind me.

I actually find it funny to see people passing me doing 65 or so while im doing 55, and 10 minutes later ill see them again rolling through the toll plaza or sitting at a stop light off an exit. Makes that little ecomodder gremlin inside smile a little .

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I'm glad to hear that more and more people are looking into motorcycles to transport themselves where they need to go. Motorcycles can be very efficient and very fun. I'd just like to wish all those who decide to take the leap a very safe riding experience and a very fun one! Please understand that riding a motorcycle does have its fair share of risks. Be safe, ride clean, save gas, and have fun! That's what its all about ladies and gentlemen.