Project 100 (custom enclosed Honda C90 targets 100 mph vmax and 100 km/L FE)

[godscountry]

Originally Posted by steffen707

What about the Aprilia RS 125? That's 2 stroke, probably won't have as nice fuel economy as the 4 stroke, but more power to achieve that 100mph figure. I havn't looked up specs, but typically 2 stroke has more power per CC.

Actually after searching i found on some sites it was 27hp, or 33 unrestricted. Also noted that its top speed was 100mph. Sure the aerodynamics of your project will be way better, but i'm wondering if the low hp figure I read in the earlier pages will be enough. I still have 10 or so pages to read up on.

He could also modify the engine to produce more power,without upsetting it's fuel sipping ways at cruise speeds,while still producing that top end power.

[godscountry]

Originally Posted by visionary

So here is my first project update. Images are of the Honda C90 motor, which I am using and the rear wheel/tyre & swing arm.
Motor first. I bought a blown motor (seized big-end) to use as a dummy for fabrication purposes. I’ll swap it for my good unit when I strip the bike apart, but I don’t want too much stuff apart at once. I’m using the electric start version as kick starting will be impossible with the motor mounted below the seat and fully enclosed by chassis and bodywork. The starter adds a bit of height to the assembly but without a purpose built unit I don’t think I can do any better. The carb needs to be remounted – eventually I will go to fuel injection but in the short term I will cut-and-shut the inlet manifold to create a lower profile. This part will sit just below the bend in my knees, so it can be a bit higher than the seat base.
The rear wheel assembly is from a Kawasaki ZR750, no idea what year, I just bought it from a motorcycle breakers because I liked the fat 160 rear tyre. Despite the difficult aims of this project I continue to make compromises because this thing has to look “cool”. I know mass and drag penalties will come with this set-up but running around on skinny tyres could kill the attractiveness of the finished article.

Craig Vetter has a point about the best vehicle being your first choice, and for me there is great appeal in a “good-looking” machine. In the few weeks that I have had the C90, my eyes have been reopened about the practicality of motorcycles. Although I have always considered myself a “biker” the truth is that I have not used a bike as regular transport since my teens. They make great toys but no way would I choose one over my car for anything but a “fun” journey.

have you thought about doing a couple of basic engine modifications,like a exhaust tube header,less restrictive muffler?You might even consider more engine mods,after you get the bike handling well,some times you can gain power without upsetting the cruise and mpg performance numbers.

[visionary]

Reply to godscountry - yes I have planned engine modifications. As you rightly pointed out, there is plenty of scope to raise the engine power output in order to reach my primary goal. The C90 motor in its many guises has a wealth of tuning products available, but I hope to achieve my 100mph goal with only limited tuning.
I intend to increase capacity from 85 to 100cc, improve cylinder head flow, install a modified camshaft, utilise a less restrictive exhaust system and fit programmable fuel injection. The net result of these changes will (I hope) give me 12-14bhp, but retain useful driveability.
Recently I have been reflecting upon the lack of a specific fuel economy target in my goals, and the tuning route would seem counterproductive to a vehicle that is all about FE.
It would seem fitting (in light of the Project 100) nametag to aim for 100km/litre at 100kmh, but I think that’s just a bit beyond my reach and I would need to compromise my ideas about style.
Thanks for your interest in the project and suggestions – keep them coming!
Pete

[theo22]

what kind of camshaft are you thinking of?
Most tuningcamshafts i have seen (takagawa) will give more Hp but then the maximum torque comes at a much higher Rpm, forcing you to drive in a higher rpm
These are usually not very fuel efficient.
The beaty about the c90 and the anf125 engines i think lies in the fact that you have maximum torque at relative low rpm. the stroke is more than the bore of the cilinder
and the camshaft is also designed for this.
I think long stroke engines are the best choice for fuel efficiency.
The are becoming scarse.

[Grant-53]

A couple points that might help. Use some aluminum to extend the cooling fins on the engine for more surface area. At high temperature an alcohol/water mist could be injected into the cooling air stream near the engine. The lower body should be rounded in front as in the third sketch and then swept up toward the rear as an inverted wing. Extend the rear body work behind the rear wheel about 12 inches. Seam weld some gusset plates to both sides of the frame triangles mounting the steering subframe.

[visionary]

Looking for ideas

I’m working on a challenging section of the project, and I’m hoping someone will be able to come up with a suggestion that will help me find a simple solution. So far, in this thread, I have been pleasantly surprised by ideas that I had not considered.

I’m doing the braking system on the vehicle. What I have are original donor motorcycle components –
Front wheel (CBR600) – pair of discs mean effective diameter 250mm, pair of sliding two 21mm piston callipers
Rear wheel (ZR750) – single disc, mean effective diameter 220mm, single (sliding) two 27mm piston calliper
Master cylinders – Brembo ½ remote reservoir type

My aim – to arrive at a solution making the best use of the parts that I have, achieving a well-balanced linked system, with a single (left) foot operated brake pedal.

The dilemma – my vehicle has a much lower centre of mass, longer wheelbase, and more rearward static weight distribution than a traditional motorcycle. Therefore the forward weight transfer will be much smaller than normal. In order to achieve a reasonable balance between front and rear baking power I need to increase rear brake performance.

My questions are
On other “linked system” motorcycles, what front rear split is employed?
Other than the traditional racecar “balance bar” method, are there other simple ways to provide adjustment?
Am I being too “fussy” for a 90cc vehicle?

My last resort options are – smaller master cylinder diameter (rear), larger disc (rear), second calliper on rear, or pressure limiting valve on front, none of which I like – do you have any suggestions?

[euromodder]

Originally Posted by visionary

Looking for ideas
On other “linked system” motorcycles, what front rear split is employed?

Honda uses 3-piston calipers, at the ratio of 2 Front to 1 Rear pistons in their DCBS when the front brake is applied - this reverses when the rear brake is applied.
Applying both brakes operates all pistons on both ends.

All that is off course with the rear brake being a smaller, single disk as opposed to the big dual front disks.

Am I being too “fussy” for a 90cc vehicle?

Not if it's going to go fast due to streamlining.
It'll need good brakes - but not so good that you'd easily lock them up.

The CBR's twin brakes are going to be overpowering the front tyre anyway - regardless of the static weight distribution and dynamic redistribution.

do you have any suggestions?

Single CBR rotor fore and aft ?
You'd already have most of the hardware (splitters etc) while it remains a simple 2-disk system.

The volume in the regular CBR front brake cylinder would be sufficient to operate both disks.

Use braided brake lines to offset an increase in brake line length - you don't want to use soft, swelling rubber brake lines over long distance.


More braking power at the rear.
Reduced braking power up front - I doubt you'd need a braking system designed for 150+ mph ?


Another approach :
Calculate the energy the brakes need to be able to dissipate using Vmax and max. weight for your vehicle, compare that to the value for the CBR, and see how much of its braking power you'd need.


Something else to calculate and guestimate :
Weight on the front fork.
Make sure you don't put much more weight on the CBR front forks than the CBR+rider normally does - you'd risk bottoming out the springs under braking which leads to easier lock-ups.

If the vehicle turns out to weigh more than the stock parts were designed to handle, you'd need to improve the suspension components.

[euromodder]

The Monotracer and E-Tracer seem to have retained the now almost default twin front disk set-up, but use an enlarged rear disk that's pretty much the size of the front - so the rear disk is a lot bigger than on most road bikes.

Then again, it's designed for 150 mph.

[sendler]

Originally Posted by visionary

Looking for ideas
achieving a well-balanced linked system, with a single (left) foot operated brake pedal.

Starting with a CBR250R as a donor would be the easiest way to come up with linked ABS as it is offered on this bike and works perfectly. And they are cheap. They sell for $4,500. The engine would also be the perfect choice to chase 100 mpg at 100 mph with advanced streamlining such as a lay down recumbent land speed shell. When Vetter gets his fairing finalized this might come close right off the shelf. It would certainly do 100 mpg at 100kph to surpass the challenge. Could probably tweak the cam timing and gearing to the everyday normal riding range of 120-130 mpg at 100kph Pulse and glide could be higher. 100mph is ridiculously fast.

[redyaris]

An other issue to consider is the traction available at the tyre [tire] road surface interface. I suspect that you may already have more brakes than your tires can use, front and rear. You may want to calculate how much force the tire will take before it loses traction then design the brake system accordingly with what you have on hand. a "bigger" brake system than you need only reduces the force required to get max deceleration or lockup!

Some Brainstorming crazy Ideas

Modify the CBR twin disc front wheel by removing one of the discs and replace that disc with a sprocket adaptation.
Get other front wheel with same size single disc as CBR front wheel.