35cc Honda 4-Stroke= 30mph!

[Petrock's 1984 Spree]

Well im putting the moped on hold for this thing. Its a school project to get the most mpg. Many schools in Iowa compete ever year in Altoona to see who made the best one and i think our design is going to kick some a**!

Here's the pics so far!
downsized_0204111642 by jpetrak, on Flickr
0221111546a by jpetrak, on Flickr
0221111546b by jpetrak, on Flickr
0221111548 by jpetrak, on Flickr
0223111723 by jpetrak, on Flickr
0221111652 by jpetrak, on Flickr
0223111723a by jpetrak, on Flickr
0309111639 by jpetrak, on Flickr
0330111705 by jpetrak, on Flickr
0330111705b by jpetrak, on Flickr

[Petrock's 1984 Spree]

The frame is inch by inch aluminum square tube, wall of it is 1/8th thick.
This thing is so light you can lift it with your pinky finger!

29'' super light front wheels, 120psi max. 20'' Rear drive wheel, 115 psi max.
So far everything has been fairly easy but were starting to maching our own giant 138th sprocket.

Yeah, 138 tooth Its gigantic, and its going to mount onto the disk brake mount holes that are on our rear wheel.

So we will mount an aluminum hub to the disk brake mount, then mount the giant sprocket to that aluminum hub. The Sprocket is so big we have to make it in 2 pieces because our mill can't handle it.

The sprocket is going to be about 17''x17''.
This is the engine we have, we adapted it to run on a briggs and straton electric starter too

Little 35cc weed wacker engine lol.

1.2 lbs-ft. of torque at 5500 rpm. Tons of power!!

So were maching the aluminum hub. We already broke two milling bits, and figured out the cutters can only chew up .005'' of aluminum per pass. And we have to mill off .25''

Thats a 4.5hr job Just to mill it to size, then we have to mill in all the holes and everything else. Big, PITA job lol

Should be sick when its all done though!!
0330111700 by jpetrak, on Flickr
0330111659 by jpetrak, on Flickr

[eliteguy50]

Why did you sheet over the backrest?

[motormike]

Great stuff.......like the ground clearance......I'm with eliteguy....no sheet on the seat back......what a drag, and weight. I'll bet you've got some elaborate bodywork to make the seat a moot point.....

[Petrock's 1984 Spree]

Why did you sheet over the backrest?

Mandatory 3/16th'' firewall

I think the worst burn you would get from a 35cc would be singed arm hairs
Oh well

Great stuff.......like the ground clearance......I'm with eliteguy....no sheet on the seat back......what a drag, and weight. I'll bet you've got some elaborate bodywork to make the seat a moot point.....

Oh yeah. Gotta love when the retailer states they are 29'' wheels and they turn out to be only 27 and 7/8th''.
Originally we were going to have 1 inch of clearance, so we had to adjust the wheel mounts to make the 1'' again.

Ah, the seat. Well when im driving it, i will be laying down almost flat. So i dunno if you could even call that a seat?

[eliteguy50]

Is the height mandatory? Does it have to be flat? You could bend it for a slight wedge or gap it off the frame.

[Petrock's 1984 Spree]

No, the height isn't mandatory. But its only about 30'' high. So just enough for the driver to get his head and shoulders up to be able to see whats in front of him.

Nah, it doesn't much matter because were going to make a fiberglass body shell for the car as well.
The "race" is in mid may at adventure land so were really squeezed for time now trying to get it all done.
So we will see if we can get to the shell or not.

There are some real frankestein machines that show up. There was one vehicle last year that the driver sat 4 feet off the ground and every time it made a turn the entire vehicle would lean. They had to put training wheels on it so it wouldn't flip over
Its a blast to see all the different designs.

Perry and Pella are the two schools to beat, they have about 650 mpg with their cars. But they have been upgrading them over about 5 years or so. Its insane!

[eliteguy50]

Is Pella the one with the solar powered hybrid?

[Petrock's 1984 Spree]

I'm not for sure which one has what unfortunately.

One of those two has an electric hybrid car that ran for FOREVER last year. Last year was nuts.
We had so many mishaps during the race.

Our first problem we didnt put suspension on it so the senior last year went over a bump and the chain slipped off the jack shaft.
Then at one point in the race our engine came off its mount and was dragging across the ground
Amazingly we were able to put it back on in 5 minutes and went back out and kept on going!
And lastly, after the race we figured out the allan keys holding the sprockets on had flown out during the race so we were losing a TON of efficiency there.

So we learned a lot haha. Blue loctite will fix most of the problems

[motormike]

about 650 mpg



thats a mind -boggling figure ya got there, sonny

[noiseguy]

Concerned with your front wheel hangers. The triangles don't line up viewed fore/aft; your strength to bending there is only as good as a 1" x 1" x 1/8" piece of aluminum. This is where the frontend will break, and it's subject to bending and torsion forces in this design. Would suggest that you either tie the top together or triangulate to the full height of the support.

Why the massive sprocket, vs. a jackshaft? Efficiency?

[Trafficjamz]

Where do you dive this thing when it is done?

Is it around and around a track? Or does it go on public roads?

I assume not off-road.

[Petrock's 1984 Spree]

Concerned with your front wheel hangers. The triangles don't line up viewed fore/aft; your strength to bending there is only as good as a 1" x 1" x 1/8" piece of aluminum. This is where the frontend will break, and it's subject to bending and torsion forces in this design. Would suggest that you either tie the top together or triangulate to the full height of the support.

Why the massive sprocket, vs. a jackshaft? Efficiency?

Yeah the front hangers aren't 100% true but oh well. Its *shudder* close enough.
We made sure to beat the hangers level after we tack'd them. So if they are off, its not going to affect the wheels
Its all about being as light as possible and using the least amount of material possible. So yeah we could really beef this up and make it sturdy.

Or we could just try to dodge all the bumps in the road and pray

On the sprocket, it is all about efficiency there. Last year we went with a jackshaft and it was just a big pain. Plus you need to transfer power through more objects using more chain. If we just go one tiny sprocket on the engine to one giant on on the back you simplify the drive train and increase effiiciency.

Where do you dive this thing when it is done?

Is it around and around a track? Or does it go on public roads?

I assume not off-road.

LOL this thing wouldn't last 3 seconds off road. We go out to a giant parking lot were they lay out an 1/8th mile oval track with cones.
I really hope we can get some testing in before we take it up there. The hub for the giant sprocket is almost done and the steel for the gear should arrive saturday.

The gear and the hub should be done monday night and be ready to mount up!
Then we just have to adjust the steering controls, make the engine mount, and make the fiberglass body.

[spree-rider]

sproket and chain are worse. since your just building it in a small shop odds are your deffinitaly not going to get it allined properly. so even on the smallest bumbs the chain will bounce off.

[Petrock's 1984 Spree]

The sprocket and chain are better for efficiency.

True, we dont have a jig or any way to line it up down to the thousandth of inch but we can get it d*mn close.
As for the chain bouncing off on the bumps...it didn't last year so were looking for the best of luck this year as well.

There are flat slabs of track with no bumps, you just have to identify them pre-race so you know what to avoid.
It'll all work out