Buying a bike for MPG/Vetter Challenge, what would be your favorite?

[sendler]

The new Honda PCX scooter would make a great starting point for an around town streamliner project. I am starting to see second hand availability at $2800. It is getting 105 mpgUS stock at 35mph and has a really nice new engine which is unique in the two wheeled world as being quite under square bore/ stroke. It also has the worlds first? engine start/ stop system for a two wheeler? But The PCX is too small for Vetter class, cross country use. Only 11hp. Top speed would need custom gears to get beyond 60mph if there is any wind and the 14 inch wheels could be bigger.
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http://world.honda.com/PCX/spec/index.html
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[Ken Fry]

Originally Posted by Frank Lee

96 is about 8 better than any figure I've ever seen for CVTs. Must be a scooter unit with a much more pliable belt and lower pinch pressures.

Carlisle says at least 94% for variable v-belt drives, up to 99% for other types.
http://www.cptbelts.com/pdf/misc/ene...efficiency.pdf

I can't think which scooter has a belt made of zillions of individual plastic pieces I was thinking it was a Burgman, but I just watched a video that showed a conventional-looking belt. The one I have in mind looked to be very low hysteresis.

[sendler]

Looks like there are some bending losses with belts in addition to the slipping and compression losses in a scooter CVT. Hence double cogged belts to let them bend easier. 5 or 6% total loss is not a deal breaker I guess to get a lower seat height than you can get with a sport bike frame, and to eliminate shifting. It will be interesting to see what Allen comes up with for a forward shifter. Now that he has lowered the seat of his Ninja to the minimum in anticipation of a feet forward cruiser position inside the new nose, it looks very cramped to get onto the stock pegs for shifting. I also just noticed that Honda USA has dropped the SH150i in favor of the cheaper PCX which is not big enough to ever go 70 mph. Looks like the pre gen Ninja will stay the defacto used bike starting point for the soon to be ready Vetter streamliner kit. The better ones will then have to add an Ecotrons EFI conversion and find some way to de-tune the cams.

[sendler]

Here is a used Honda SH150i that has been modified with paint and a headlight which will only serve to knock the value down. 900 miles and they will be lucky to get $2800.
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Honda : SH-150 Honda : SH-150 - eBay (item 180819802520 end time Feb-20-12 23:00:00 PST)

[Frank Lee]

Originally Posted by Ken Fry

Carlisle says at least 94% for variable v-belt drives, up to 99% for other types.
http://www.cptbelts.com/pdf/misc/ene...efficiency.pdf

I don't see anything in there re: variable drives a.k.a. CVTs.

[Ken Fry]

Originally Posted by sendler

Looks like there are some bending losses with belts in addition to the slipping and compression losses in a scooter CVT. Hence double cogged belts to let them bend easier.

The Burgman 650 belt has individual steel segments, and two Kevlar bands.


Here's a broken one. (Evidently they last about 50,000 miles or more.)


Still haven't been able to think what scooter has the plastic segments -- but it was Burgmanesque, with the pulley adjusted electronically, rather than with flyweights, etc.

[Ken Fry]

Originally Posted by Frank Lee

I don't see anything in there re: variable drives a.k.a. CVTs.

This is what they are talking about when they say "agricultural variable speed" on pages 2 and 9. Combines (and other ag machines) use continuously variable drives to adapt travel speed to thrashing speed, etc. These applications are particular demanding and require tough belts, which you would expect to have high bending losses (typically) high bending losses.

Here's a vendor for such belts:
Variable Speed Belts - Quality Power Products

This describes how these drives are used.
Viewing a thread - 1440 combine rotor drive belt problem?

[Grant-53]

On any machine look at the power to weight ratio and the rpm of peak torque. The aero drag force at speed determines the power needed. Note that Charlie Perethian used a Honda 250cc single to get 157 mpg at the Vetter Challenge that is very similar to the new CBR model. The high mpg records of the 80's were set by 125cc bikes with full body fairings.
Over the years in the auto parts business I sold tons of belts of all types. The manufacturers such as Gates and others offer a wealth of information.

[jkv357]

Originally Posted by Grant-53

On any machine look at the power to weight ratio and the rpm of peak torque. The aero drag force at speed determines the power needed. Note that Charlie Perethian used a Honda 250cc single to get 157 mpg at the Vetter Challenge that is very similar to the new CBR model. The high mpg records of the 80's were set by 125cc bikes with full body fairings.
Over the years in the auto parts business I sold tons of belts of all types. The manufacturers such as Gates and others offer a wealth of information.

As I understand it, the conditions and speeds were much different in older Vetter Challenges than what is required for today's challenge, with no requirements for cargo and no minimum speeds.

I assume the record of 470MPG was done at lower speeds with a good amount of P&G, because the winner had the trans modified with a neutral available from top gear.


Jay

[Grant-53]

There were minimum speeds for the older events and P&G has not been used from the comments Craig made in other posts. Check the website to be sure. The Cargobike variant of the Aprilia scooters have a 125cc model and look slick. Someone may find a Kreidler 50cc racer and cover it with a full body fairing.