I have a VT500 honda I'm currently hovering near 60 mpg I'm hoping I can push it up to 70 mpg. I'm thinking about trying to find a better windshield (rifle probably) and perhaps a taller rear tire (it's already geared as tall as is available). after that I guess I would have to start enclosing the bike (not something the wife wants me to do)
Unfortunately, with a shaft drive moto you can't change the gear ratio as easily as a chain drive moto.. maybe try different viscosity gear oil, motor oil.. reduce the friction all around... pump tires up to max pressure... better sprkplugs... check your brakes/wheel bearings for rolling resistance.
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all that has been done I'm running conventional oil in the crankcase 5-30 it calls for 10-30 I didn't feel safe going 0-30 due to the age of the bike. The final drive has redline synthetic in it 70-85 and it called for 80-90. I'm running the tires at 50 psi. And finally I have installed a shadow final drive it has 15% taller gearing. I think the only things I can do now are aero changes.
You're doing pretty darned good on MPG. I've never gotten over 52 MPG on my V twin CX500 and usually get in the low 40s. IMO over inflating motorcycle tires, particularly the front, isn't a good idea because of the way it affects handling.
I just checked I'm only at 40 psi. I think I've done everyting I can other than aero so I guess that's next. perhaps I'll look at a hurricane 600 body work and see if it could be made to fit. not ideal but if it can get the rider out of the wind it's an improvement.
Streamlining could be cool, how good are you with fiberglass? Craig Vetter's streamliner challenges in the past have seen 500-700mpgs. Macine oil in the driveshaft would reduce resistance, but I am not sure about any side effects...
My 250 Ninja only gets 80mpg max with aero and gearing mods.
2007 Kawasaki EX250 Ninja | ZG250 Quarter-Concours
15/41 gears, rack and top case, saddlebags, tank bag, tall windscreen, etc... zg250.blogspot.com
Yeah, body work is a big thing. Everyone keeps reminding me that drag is based on frontal area too, but in my opinion there's no reason for such a light, small engined 2 wheeled machine to get such 'bad' milage (that is most bikes get 40-50MPG and civics can get that...). I think it's because they sit so tall. I think to really make a huge difference you'd need almost a recumbent style bike so you can reduce height by half and then fit a streamliner body.
For now though you could probably revinyl the seat and shave the foam to sit you a couple inches lower, get a wider, more bubbly windshield and tuck in more. On the sides you could smoothly connect airflow over engine bay and to the rear. If you look up streamliners for bicycles you'll see some use spandex type fabric so they can actually fiberglass over where their legs go and have a spandex area they can push feet through to 'put their feet down', but to dismount they'd have to lift each leg up and out of the 'hole' of the body.
There's lots of extreme stuff I'd like to try but I should start on my cars first and eventually get one of the bikes running correctly .... or at all....