First impressions of a small motorcycle commute

[dcb]

Finally! I got a convergence of halfway decent weather and having my new bike in one piece (81 suzuki gs 250). I finally drove it to work today and it was a lot of fun.

I have done a fair bit of hypermiling/P&G/EOC in a stickshift car. And I have owned bikes of all sizes in a more rebellous past (no clue about hypermiling at the time). I have to say this is something of an adjustment.

The most obvious change is that this thing does not glide near as far as my cars, or my 75 le tour. Even if you dig all the way down to neutral while you crest a hill at 50. Hills that I would accelerate down while EOCing, I was decelerating on today. That will need some work, somehow. Lighter bearing grease, more psi, aero, more neutrals?

The other obvious thing is that the 6 speed gearbox is really close. I had no problem starting in second, shifting to 4th, then shifting to 6th as an experiment. It does about 5300RPM at 50mph with the stock 15/47 sprockets. I have a 37 tooth sprocket en route that should make the gears more useable, but as it is, I'm shifting at 4000 and stay in 6th gear down to 30mph. The new sprocket will make 4th feel like 6th does now.

And this bike isn't exactly a lightweight at about 300lbs, plus I rigged a 5 gallon tank off a 750 on there. But for a small handful of hundreds, it is definately a good value.

So given the bikes limitations, I do feel that timing the lights/obstructions becomes even more important. I cannot glide very well currently, so I have to make up for it somehow, i.e. dwl and avoiding coming to complete stops unless I can sit there with the engine off for a bit.

I considered all two/three wheeled options that I could think of for efficiency, bikes, recumbents, electric bikes, velomobiles, scooters, mopeds. I settled on a small motorcycle (and 250 is a bit overkill) because:
1. very affordable.
2. I can keep up with traffic, no problem.
3. there was no good bike route to my destination 20 miles away.
4. it had the range I needed
5. There is no question as to the legal status or speed/weight limitations

Anyway, I'm smiling

[boxchain]

Very cool. My DD was a 73(?) Honda CB350-4 many many years ago. I picked it up for $100, replaced the battery, tires, and the muffler, and ran the hell out of it. I would get 50-60 mpg trying to qualify on pole.

I've been wanting another, and riding season is starting here. Hmm...

To glide you need momentum and low friction. I don't think that pumping up a bike tire is as good of an idea as a car tire, since blowouts can be a big problem. Momentum is mass * velocity, so with your low mass, low momentum.

[extragoode]

Sounds great. I finally got my bike, '81 Honda CM400E, in working order just in time for it to get cold last fall. Definitely check the tire pressure. Mine seemed like it was slowing down really fast even when I was holding the clutch last year, so I checked the pressure. Bumping it up from 25 to 40 or 45 made a world of difference, but the tires didn't LOOK low at all before I filled it up. Also, you're just not going to get the same coasting distances out of your bike as you would a car. All things considered, bikes have pretty miserable aero and you don't have all the extra mass and rotational inertia that 4 wheels and a passenger compartment has, but that's ok, because you're burning less energy to get going. Crotch rockets have slightly better aero with all their farings and such, but I don't think it's enough to matter.

[Coyote X]

Don't pump the tires up more than they are rated for, it makes the bike ride pretty badly and can make it unpredictable in the corners

Make sure the bearings have good grease and oil the chain regularly with something like chainsaw bar oil. That seems to work the best for me, it holds up and doesn't sling off the chain like used motor oil does.

I never have tried pulse and gliding on my bike. It is tall and since I sit straight up on it I slow down really fast. I bet if you could get the aero even slightly improved on your bike it would probably make a huge difference in coast times. Maybe try a small windshield that is as wide as your shoulders. That could help direct the air a bit better than just hitting you straight on.

If you don't know the mileage you are getting now, riding it as it is for now would be a good thing to do to get a baseline mileage number so you know what changes actually help.

[dcb]

The 37 tooth sprocket showed up today

I quickly slapped the vacuum gauge on the bike so I could try and get some indication of where the peak efficiency mph was before doing the swap, LOL, it wouldn't break 5 inches, it was pretty worthless as a gauge with only a single 125cc cylinder attached to it, bouncing like crazy at idle.

Oh well, the proof will be in the pudding hopefully. Gotta figure out some kind of mpg gauge for these carbureted vehicles.

[MetroMPG]

Have you been tracking your fuel consumption on the bike the old fashioned way since you started riding?

[Ryland]

I had a vacuum gauge on my cb125 for a while, to get rid of the bounce I stuff some air cleaner foam in the hose, a small air chamber would help smooth out the pulses as well.

[dcb]

Metro, not ridden it much at all with the snow and rain, need to get the fairing on. I haven't topped off the rigged 5 gallon tank once yet. I'm focused on the MPG instrumentation at the moment, but will probably put the 37 tooth on and see what it drives like. Hopefully I can get to a point where I can do an A-B-A test on it and:
1 land on the "A" that is more fuel efficient
2 not take tankfuls to complete testing

Ryland: thanks for the restriction in the line tip, is 5" of vacuum normal?

[dcb]

Got the new sprocket in. WHAT A DIFFERENCE!!!! I have to think they made a mistake with the stock sprocket, It takes a little more care to get rolling in first, but no major slipping and it (and all the other gears) are a lot more useable. It HAS to be better MPG

[MetroMPG]

Sounds promising. If only cars were that easy to re-gear.