HF 79cc Utility Bike

Felton said:
I don't know if your dead set on chain for the first reduction but here is a centi cluch for a belt.

This is the same one I am using you would most likely have to by new springs.

Mini Bike GO Kart 5/8 Bore Belt Clutch - eBay (item 180592837555 end time Dec-03-10 16:27:56 PST)

here are the springs you would need.

200114A - Red springs for 350 Series Clutch. 1800/2000 engagement. Set of 2. Standard.
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OK, so now you guys have me intrigued over the use of a belt in the primary drive. When using a centrifugal clutch with a v-belt, is it quieter and/or smoother?

Has anyone combined a v-belt primary drive (to a jackshaft) AND a belt to the rear wheel? Seems that belts wouldn't really have a driven side and a slack side like a chain does, so depending on where the jackshaft is positioned, you might have to find a way to split the chainstay to use a belt on the secondary drive. I'm not real keen on that idea.
 
Has anyone combined a v-belt primary drive (to a jackshaft) AND a belt to the rear wheel?
Click to expand...

I think there was some one doing that with the ezm trannys. You might want to check with one of the dealers to see who it was.

As for the other questions I have an opinion and its about the same as what you thought, but it is just that, an opinion, and should not base anything on it.

Here is another belt driven cent. clutch by comet.
 
Yeah....you can find a belt tensioner setup on a (lawn tractor/ 1 and 2- stage snowblowers, big rototillers, etc)much simpler, but you'll only have one speed. yeah, belts wear somewhat quickly on a tensioner setup, and less on a comet clutch. i would go with the comet clutch-jackshaft w/ sprocket on the other side for your drive wheel, it would stay right-hand drive on the wheel. too many belts and you'll rob power. you'll find comet-type clutches on snowmobiles, golf carts, go karts, quads. its the best setup for going fast, having constant power. the rpm's will stay the same from 0 to wherever it tops out, buy extra belts, much cheaper then clutch shoes.i have a derbi moped with a comet-type setup on it...we use it as a dirtbike, complete beast, when we went to contact owner for title, the last person (the son) died while riding it. we got the title though
 
Well, I decided on chain primary and secondary, I suppose mainly because I am a little fearful of belt slip in the rain. I realize that I could have covered the primary belt and that would alleviate 9/10 problems associated with belt slip in rain. But oh well... I bought my first transmission part, a Max-Torque 04-458 centrifugal clutch. It's a 5/8" shaft with 3/16 keyway (to mate with the Harbor Freight 79cc engine). Got it for $23.00 shipped (bargain on ebay- not a sale or anything like that). So let the bargain parts collecting begin!
 
Got a 10ft piece of #41 chain from Tractor Supply, and a bag of (4) extra connecting links for $20. That place is great! There are some really good deals, and some things that are a bit overpriced. I saw they had v belts and lots of different sizes of 5/8 pulleys, so it looked like you could pull together all the parts for a belt transmission (minus the clutch) for 50-60 bucks. Some of those pulleys looked to be at least 6" diameter, so you could get some pretty good reduction using a belt.

How big of a problem is belt slip in the rain?
 
I would think it would grip pretty good beacause older cars ran only belts on the ac ad alternators and befor that generators in the rain and fording crek's




V
 
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From OMB Warehouse, my jackshaft.


SKU Product price Quantity Total
AZ8555 5/8" Jackshaft Collar $1.25 4 $5.00
AZ8442 3/16" x 3/16" x 1-1/4" Key Stock $0.32 2 $0.64
AZ8175-10 5/8" Jackshaft x 10" $6.00 1 $6.00
AZ8206 5/8" x 1-3/8" Precision Sealed Bearing $1.87 2 $3.74
AZ2108 #40/41 Chain 17 Tooth $11.65 1 $11.65
AZ2102 #40/41 Chain 9 Tooth $7.35 1 $7.35
Subtotal: $34.38
Shipping cost: $6.00
Total cost: $40.38


Price seems to be about the same as those kits you can buy everywhere, except that this combination will allow you to use 40/41 chain on a 5/8" jackshaft, whereas most of the kits have 3/4" jackshafts for 41 chain.

By my calc (thanks Felton), I should be able to get anywhere from 7:1 to 9:1 reduction easily with this setup.

So total cost so far:

Harbor Freight 79cc engine $72.00 Harbor Freight
Max Torque 10 tooth clutch $22.00 including shipping
41 chain and links $20.00 Tractor Supply
jackshaft $40.00

So my total so far is $154.00. I expect to use recycled frames for the utility bike frame, as well as all the other bike components. I plan on keeping the HF engine intact, may eventually do something with the exhaust.

So the only other purchase needed is the rear wheel sprocket; I'm thinking I might devise a way to attach a sprocket to a rear disc brake hub.

Does anyone know if it is possible to run a 41 chain on a regular bike (7 speed) chainring? That would enable me to get anywhere from 28 teeth up to 48 teeth on the rear wheel with no problems, as those kinds of chainrings are everywhere.
 
I still think you need to go higher than 7/1. 7/1 is about 60 mph 9/1 is about 45 mph. If you click on my name and select public profile it should take you to my page where I have some caluculations for speed.

I like the idea of the rear disc brake and sprocket. Just to the left of corgi1's post is kings sprockets. You might benifit from looking through there sight. ;)
 
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Felton said:
I still think you need to go higher than 7/1. 7/1 is about 60 mph 9/1 is about 45 mph. If you click on my name and select public profile it should take you to my page where I have some caluculations for speed.

I like the idea of the rear disc brake and sprocket. Just to the left of corgi1's post is kings sprockets. You might benifit from looking through there sight. ;)
Click to expand...

Good idea on Kings website. I was thinking of just creating an adapter to use a normal chainring off a bike crankset; that would allow up to around 50 teeth easily. But I'm not sure I can use a normal bicycle chainring with a #41 chain? I think the pitch is the same but the width is not.

As for ratios, going from a 10 tooth clutch to a 17 tooth jackshaft yields 1.7:1; then 9 tooth jackshaft to 50 tooth rear wheel yields 5.5:1, so a total of 9.35:1 final (think I did that right?). So my final gearing will be dependent on the rear wheel gear.

A 40 tooth rear gear (common on china girl kits?) will yield a 4.4:1 ratio, so 7.5:1 final.

I think I remember some posters saying around 9:1 would be good enough to have ample torque on the low end?
 
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I guess it all depends on how much you are planning on loading on your bike. If it is not going to be much more than just you I would bet 9.35/1 would be ok. If you are planning on loading it down you are going to want to get a larger reduction.

All your ratios look good

Even by putting this sprocket in place of your 17t would get you up around 13.3/1. You might be surprised at what it would do to your acceleration and what you would be able to haul.

As far as the chain and chainring goes I have no idea.

I can't wait to start seeing pictures of this thing!!!!
 
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I too have been following your progress, and can't wait to see the final thing. Great information. Thanks so much for sharing it with us.
Roofman6
 
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