Tire sizes

[Reveeen]

This is just a basic guide to get you pointed in the right direction.

10" Tires

2.50x10 : 2.5"W x ?"T
2.75x10 : 2.8"W x 15.6"T
3.00x10 : 3.0"W x 16.5"T
80/90/10 : 3.1"W x 15.7"T
90/90/10 : 3.5"W x 16.4"T
3.50x10 : 3.5"W x 16.5"T
100/80/10 : 3.9"W x 16.3"T
100/90/10 : 3.9"W x 17.1"T
4.00x10 : 4.0"W x 18"T
110/80/10 : 4.3"W x 16.9"T
120/70/10 : 4.7"W x 16.6"T
120/90/10 : 4.7"W x 18.5"T
130/70/10 : 5.1"W x 17.2"T
130/90/10 : 5.1"W x 19.2"T

12" Tires

4.00x12 : 4.0"W x ?"T
110/70/12 : 4.3"W x 18.1"T
110/90/12 : 4.3"W x 19.8"T
110/100/12 : 4.3"W x 20.7"T
120/70/12 : 4.7"W x 18.6"T
130/70/12 : 5.1"W x 19.2"T
140/60/12 : 5.5"W x 18.6"T
140/70/12 : 5.5"W x 19.7"T

13" Tires

110/90/13 : 4.3"W x 20.8"T
120/70/13 : 4.7"W x 19.6"T
130/60/13 : 5.1"W x 19.1"T
130/70/13 : 5.1"W x 20.2"T
140/60/13 : 5.5"W x 19.6"T
150/70/13 : 5.9"W x 21.3"T


Just some info on tire fitment, potential gear ratio impact, and speedometer error (stolen from 49ccscooter.com).

[katoranger]

That is good info. Will be using this for the CT70 project. The taller the tire the better for it.

[Reveeen]

Now all I need is someone to offer up a final drive gear ratio for a GY6 engine!

I have a buggy engine I'm trying to convert over for use in a scooter.

No one seems able to tell me what should be in there for a ratio.

There are too many available:

http://www.partsforscooters.com/Gear...ategory=124370

(trial and error will get expensive in a hurry!)

A fellow in Britain told me a 15/42 gives a good 40mph cruise. (2.8:1)

[Weldangrind]

Do you have access to a dead GY6 Elite engine? Maybe you can find the answer on an Elite forum.

[Reveeen]

Whatever I do, it will be a stab in the dark, so to speak.

I am using a short case engine, meaning: 3:50 X 10 (or 16-16 1/2" tire) maximum.
My horsepower is unknown, meaning: I don't expect I have a high horsepower version of the GY6 engine, maybe 8? (it could be less)
I have been given a ratio of 2.8, giving a cruise of 40mph, on a unknown tire size. (I'm expecting a 19-20" tire)

My choices are: 2.25, 2.31, 2.37, 2.4, 2.46, 2.53, 2.57, 2.64, 2.71

A "safe" bet would be a 2.57, or do I go with a 2.4-2.46, and if I can't pull it, try to make more horsepower?

[Weldangrind]

You could stick with the 2.57 and try to make it rev higher.

I've tried several gear calculators, and I must be doing something wrong; they're all coming in around 93mph! http://www.csgnetwork.com/rearendgearcalc.html

I used 5000 as a target, along with 2.57 final drive, 1.00 in the absence of a trans gear and 16" for the tire diameter.

[Reveeen]

There is a fixed reduction within the transmission......

You would plug in a, say 19" tire, I would *think* about 6500rpm @ 40mph. That would give us an overall reduction, from which you would remove the 2.8, giving us the fixed reduction.

BUT whatever you come up with....can my engine "pull it"?

[Weldangrind]

When you say fixed, are you referring to the gears in the final drive? I presume that's the gearset that you're trying to decide on now.

What is the range of the variable ratio belt on a stock Elite? I found this site that might be correct: http://www.motorscooterguide.net/pag...12/page12.html It indicates a primary reduction of 2.2 - 0.9, and a final reduction of 7.318:1 (I believe this to be a combination of the variable plus the fixed at a given RPM). The pics at the bottom of the page are hilarious!

Since gear ratios are multiplied when used together, I presume that we can divide 7.318 by 2.2, which equals 3.32:1. While that might be in the ballpark, it isn't on your list of available choices.

Whatever you choose, I'd stay on the low side (higher numerically). How fast do you really want to go? The stock 125 Elite had a claimed 55mph maximum speed.

[Reveeen]

Target would be 50-55 cruise.

Elites are a bit different kettle of fish. Though the claim is "patterned after", they are substantially stronger and liquid cooled. They are dialed in to cruise @ 50, again I assume around 6500, and are rpm limited at 7500.

What is in the final drive?
http://www.partsforscooters.com/Vehi...e-Transmission

The pieces that are "adjustable" are:
Gear #6 (which slides on the axle)
Shaft #7 (the large gear on #7 presses off of the shaft (for installation on the new shaft) and itself indexes with the gear on #8, the input shaft).
When you buy a "final drive gear set" you get a shaft (#7) with driver gear built-in to the shaft, and a axle gear (#6) that slides on the axle.
The Input shaft (# 8) and the press off gear (on #7) do not change. (sadly I did not determine this ratio)

How fast? Not being rpm "limited" the claim out of a GY6 is 12,000rpm, but I would not want to hold it there, let's say 60mph?

This is why I might be better going with a 2 cycle Honda engine in there, which should @90cc have no trouble with 10hp.

[katoranger]

I plan to try some alternative tires on the new elite. Currently is has 3.5x10 tires. Front is like new, but rear has some miles on it.

These are probably my options.

90/90/10 : 3.5"W x 16.4"T
3.50x10 : 3.5"W x 16.5"T
100/80/10 : 3.9"W x 16.3"T
100/90/10 : 3.9"W x 17.1"T
110/80/10 : 4.3"W x 16.9"T

Not sure on clearance issues yet, but slightly larger tires would be okay. Good all weather traction, decent handling, and decent service life would be my criteria.

I will probably right in cold temps, wet roads, and some curves.

Mostly I will be riding straight up at about 45mph and creating chicken strips.

[Reveeen]

My Yamaha came with 130.90X10 tires stock. I got a desire for better handling and went for 130.70X10 Continental Zippy tires, but found my final drive ratio messed up (though it does do an impressive wheelie now) it tops out around 35mph, so, as soon as the snow goes I'm in for an up-gear.
I do not think you have an up-gear option for your Honda (though you should check around on the forums).

Any tires you pick are, for the most part, ok in the rain. Colder temps require a softer compound (the downside being wear in the warm). I do not believe in "cheaping out" on tires.

The local dealer(s) here push Michelin Reggae tires for scooters:

http://www.michelinmotorcycle.com/in...m?event=Reggae

I would go with a Bopper: (as more of an "all-round")

http://www.michelinmotorcycle.com/in...m?event=Bopper

Though I still like my Continentals:

http://www.conti-online.com/generato...itwist_en.html

[katoranger]

The boppers are reasonably priced. I like those continentals too.

It is worth it to spend alittle more in the tire department if I don't have to change as often and improved saftey.

As for performance. I won't be trying to drag any parts so better mileage and long life is more important. Good stable handling while cruising at 50mph.

I don't know if a 130 would fit. Not alot of room back there. Also you mentioned the elite dialed in for a 50mph cruise. That is perfect for what I need.

[Weldangrind]

Originally Posted by Reveeen

I do not think you have an up-gear option for your Honda (though you should check around on the forums).

I'm surprised to hear that. So this gearbox is not the typical GY6 assembly?

[katoranger]

I think the parts are out there.

[Reveeen]

Originally Posted by Weldangrind

I'm surprised to hear that. So this gearbox is not the typical GY6 assembly?

These things have about as much relation to a GY6 as the space shuttle.

The GY6 was a joint effort between Honda and the Chinese. Something that could be built easily, and cheap, with the existing tooling. There happen to be some parts that cross over, but not many, and it's hit and miss. The design of these units pre-date the GY6 by quite a few years.

Folks just did not get into modding these things. In a/the world view they were largely unpopular, being much more expensive than smaller 2 cycle scooters. Guys just bought them and ran them. Honda too, partnered with existing manufacturers in India/Asia, so what you are left with is the specific markets of N. America, Japan, and Europe. A marketplace too small for the R+D required for a large aftermarket effort.
These are well built quality units, too expensive for the bottom of the market, and competing with a "plastic scooter" against metal Vespa and Lambretta scooters. Though well built, there was no perceived value, "scooter guys" simply did not go to a Honda dealership to buy a scooter.

Even today.... what would you rather own a "vintage Honda plastic scooter" or a "vintage Vespa/Lambretta metal scooter"?