My First Motorbike Project
- Thread starter gera229
- Start date
Placing a 36T will greatly sacrifice your acceleration.
Without a good exhaust your engine might not perform at its max rpm.
Also, my ratio is similar to lowracers. I have a 15.42 ratio. Gearbox reduction is 3:1.
Rear sprocket is 72 teeth and front is 14 teeth (I am using pocket bike chain size).
Ratio: (72/14) x 3 = 15.42.
Without a good exhaust your engine might not perform at its max rpm.
Also, my ratio is similar to lowracers. I have a 15.42 ratio. Gearbox reduction is 3:1.
Rear sprocket is 72 teeth and front is 14 teeth (I am using pocket bike chain size).
Ratio: (72/14) x 3 = 15.42.
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MrJohn,
This pocketbike engine you have if geared correctly w/expansion chamber setup correctly should get you to 50 mph. If you are heavy, maybe not or if you have friction losses in your drivetrain maybe not. I think your gearing may be too tall. I dont get as much speed out of a friction drive as I do my V-Belt drive due to friction. Makes sense since I can pedal my v-belt bike easier than the friction bike. Now 50 mph on a bike is scary fast especially a non suspended or just front suspended bike. On my Downhill full suspension tank of a bike, 50 is stable.
p.s. That pipe you linked to doesnt look like a good performance pipe...
-Lowracer-
This pocketbike engine you have if geared correctly w/expansion chamber setup correctly should get you to 50 mph. If you are heavy, maybe not or if you have friction losses in your drivetrain maybe not. I think your gearing may be too tall. I dont get as much speed out of a friction drive as I do my V-Belt drive due to friction. Makes sense since I can pedal my v-belt bike easier than the friction bike. Now 50 mph on a bike is scary fast especially a non suspended or just front suspended bike. On my Downhill full suspension tank of a bike, 50 is stable.
p.s. That pipe you linked to doesnt look like a good performance pipe...
-Lowracer-
gera, you have the same 72t sprocket and 8mm(T8F) chain I am using. If you buy Staton's rear hub, it will accept a pocket bike freewheel with a left-hand thread. Then your 72t sprocket will bolt right onto your rear wheel.
If you're mainly interested in improved low speed riding, change your 14t gearbox sprocket to an 11t sprocket. This would lower gearing from 15.43:1 to 19.64:1.
You could also ask KING's to fab you an 80-tooth custom sprocket. That lowers gear ratio to 21.82:1. In the 8-speed cassette I'm using, that's my fifth gear. After starting off from a standing start of 37.09:1, I ALWAYS end up cruising at 21.82:1, my fifth gear.
Good luck in asking KING's though. I tried, but he doesn't respond to my emails.
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MrJohn,
Going to a larger rear sprocket is what you would need if you want to get your gearing from 14:1 to say 16:1+ to allow this type engine to get into into its powerband...(not smaller rear sprocket)
-Lowracer-
Going to a larger rear sprocket is what you would need if you want to get your gearing from 14:1 to say 16:1+ to allow this type engine to get into into its powerband...(not smaller rear sprocket)
-Lowracer-
Lowracer I found your exhaust on PB Parts:
You either have this one or the other link (Except it does not say REV, but I do not think that really matters
):
Exhaust - Performance Skinny FS509 / Z600
Exhaust - Performance Skinny, X1/X2
@MrJohn
I advice from getting the stock cag exhaust because it is bad for performance. If you can chip in about $18 more get the performance exhaust for cag. And if you get spend $70 get the Jet Pro Cag Pipe, it gives the BEST flow and performance boost, but it may take some modifying and cutting to be able to fit it on.
And I doubt your bike will be able to pull the 36T without greatly burning the clutch. You can try it if cost does not bother you and let me know the results. What I just said is just my opinion about gearing based on lowracer; but I know for sure you need to get one of the good exhaust pipes.
I have this exhaust, but the gearbox gets in the way so I will need to modify it to make it fit:
http://www.pocketbikeparts.com/Exhaust_Performance_Cag_p/cgex301674.htm
The china girls 66cc/ 80cc with the 11T (stock front) and 36T rear have a 16.36 ratio and they can pull them but very slow acceleration indeed. Pocket bike engines will handle that ratio very well and since Pocket bike engines Revv faster they will pull the ratio at a faster speed and still maintaining better reliability than a china girl engine.
You either have this one or the other link (Except it does not say REV, but I do not think that really matters
):Exhaust - Performance Skinny FS509 / Z600
Exhaust - Performance Skinny, X1/X2
@MrJohn
I advice from getting the stock cag exhaust because it is bad for performance. If you can chip in about $18 more get the performance exhaust for cag. And if you get spend $70 get the Jet Pro Cag Pipe, it gives the BEST flow and performance boost, but it may take some modifying and cutting to be able to fit it on.
And I doubt your bike will be able to pull the 36T without greatly burning the clutch. You can try it if cost does not bother you and let me know the results. What I just said is just my opinion about gearing based on lowracer; but I know for sure you need to get one of the good exhaust pipes.
I have this exhaust, but the gearbox gets in the way so I will need to modify it to make it fit:
http://www.pocketbikeparts.com/Exhaust_Performance_Cag_p/cgex301674.htm
The china girls 66cc/ 80cc with the 11T (stock front) and 36T rear have a 16.36 ratio and they can pull them but very slow acceleration indeed. Pocket bike engines will handle that ratio very well and since Pocket bike engines Revv faster they will pull the ratio at a faster speed and still maintaining better reliability than a china girl engine.
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Your final drive is 14.4:1, which is slightly lower than my 7th gear in my 8-speed cassette. If you swapped to a 36t, gearing raises to 10.8:1, which is unusable for street use.
You need a larger rear sprocket. I have never seen a front sprocket smaller than 10t. High rpm engines love lower gears. If cruising below 40mph, shoot for 21.81:1.
If you think 21.81:1 is too low, worry not. My first gear is 37.09:1 and my cruising gear is 21.81:1. For higher speeds, my eighth gear is 12:1.
There is a 60t sprocket on ebay for cheap.
http://www.ebay.com/itm/bicycle-Mot...&otn=3&po=LVI&ps=63&clkid=3505387226865055761
That would lower your gearing to 18:1. This would make for MUCH better acceleration, AND you could still cruise at 35mph. Top speeds would be in the 40's.
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I think I would be fine with just an 11T rear (I have it as a spare sprocket), thanks for the info.gera, you have the same 72t sprocket and 8mm(T8F) chain I am using. If you buy Staton's rear hub, it will accept a pocket bike freewheel with a left-hand thread. Then your 72t sprocket will bolt right onto your rear wheel.
If you're mainly interested in improved low speed riding, change your 14t gearbox sprocket to an 11t sprocket. This would lower gearing from 15.43:1 to 19.64:1.
You could also ask KING's to fab you an 80-tooth custom sprocket. That lowers gear ratio to 21.82:1. In the 8-speed cassette I'm using, that's my fifth gear. After starting off from a standing start of 37.09:1, I ALWAYS end up cruising at 21.82:1, my fifth gear.
Good luck in asking KING's though. I tried, but he doesn't respond to my emails.
Can you link me to staton's rear hub? A pocket bike freewheel... Does a pocketbike even have a freewheel?
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going to order the parts in a week or so ThanksLowracer I found your exhaust on PB Parts:
You either have this one or the other link (Except it does not say REV, but I do not think that really matters
Exhaust - Performance Skinny FS509 / Z600
Exhaust - Performance Skinny, X1/X2
@MrJohn
I advice from getting the stock cag exhaust because it is bad for performance. If you can chip in about $18 more get the performance exhaust for cag. And if you get spend $70 get the Jet Pro Cag Pipe, it gives the BEST flow and performance boost, but it may take some modifying and cutting to be able to fit it on.
And I doubt your bike will be able to pull the 36T without greatly burning the clutch. You can try it if cost does not bother you and let me know the results. What I just said is just my opinion about gearing based on lowracer; but I know for sure you need to get one of the good exhaust pipes.
I have this exhaust, but the gearbox gets in the way so I will need to modify it to make it fit:
Exhaust - Performance, Cag
The china girls 66cc/ 80cc with the 11T (stock front) and 36T rear have a 16.36 ratio and they can pull them but very slow acceleration indeed. Pocket bike engines will handle that ratio very well and since Pocket bike engines Revv faster they will pull the ratio at a faster speed and still maintaining better reliability than a china girl engine.
MrJohn patience is good. Gather as much information possible from pocketbikeplanet forum before you order.
Get the correct exhaust. NOT the stock cag one. With a better exhaust your bike will probably go faster with your current gear ratio than the top speed you achieved so far.
And you will FLY past your current maximum speed with the correct exhaust. I myself NEVER knew a good exhaust could make such a difference.
So either get a performance exhaust or a Jet Pro exhaust. But not stock and skinny tube exhausts (Unless it is a performance skinny exhaust like lowracer has.).
Get the correct exhaust. NOT the stock cag one. With a better exhaust your bike will probably go faster with your current gear ratio than the top speed you achieved so far.
And you will FLY past your current maximum speed with the correct exhaust. I myself NEVER knew a good exhaust could make such a difference.
So either get a performance exhaust or a Jet Pro exhaust. But not stock and skinny tube exhausts (Unless it is a performance skinny exhaust like lowracer has.).
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The 11t sprocket is the key to engine performance.
Your 72t sprocket was specifically made for this pocket bike freewheel. The bolt holes and center register hole line up perfectly:
Man, this is an AWESOME deal! Unsure of the quality and reliability of the vendor, though:
http://www.ebay.com/itm/motor-motor...381?pt=LH_DefaultDomain_0&hash=item20b977912d
You get the custom hub, freewheel and a spare sprocket. The 72t should bolt right on.
JMO, a freewheel rear hub is a great safety item. If the engine chain jams, the freewheel prevents the rear wheel from locking up.
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order the Exhaust - Performance, Cag
and the 36tENGINE_KIT_PARTS_PAGE_2
50t eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices
ps, not at full Throttle at 35mph 0-35 mph in around 18 seconds 1/2 but at 1/2 throttle need to be at 40mph
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I think this would also work well for you. Unsure what size sprocket is on there. You could ask the vendor.
JMO, a freewheel rear hub is a great safety item. If the engine chain jams, the freewheel prevents the rear wheel from locking up.
MrJohn I would get the 60T, but you can try the 50T and let us know your results.
You can get the exhaust lowracer has and he even shows how he made it fit. The exhaust you linked is the one I have, I have not done any mods to it yet because I'm still looking to buy a bike before I begin.
But you can get the same one as I have and work it out. Check my picture to see why it does not fit and needs modifications (cutting, bending, etc.).
Picture in post #48:
http://motorbicycling.com/f4/my-first-motorbike-project-33877-5.html
You can get the exhaust lowracer has and he even shows how he made it fit. The exhaust you linked is the one I have, I have not done any mods to it yet because I'm still looking to buy a bike before I begin.
But you can get the same one as I have and work it out. Check my picture to see why it does not fit and needs modifications (cutting, bending, etc.).
Picture in post #48:
http://motorbicycling.com/f4/my-first-motorbike-project-33877-5.html
Then I do not see why you want to make it even faster lol. Why not turn the throttle more to go even faster, maybe if you get a good exhaust you can achieve 40 at half throttle?
@7HEAVEN
Can you give me a link? Because I do not know what a freewheel rear hub is lol (Haven't learned all of the vocabulary yet.)
The link is on #94.
Most rear hubs accept a right-hand freewheel and a sprocket/cassette. This custom hub accepts all the stuff on the right side, and a left-hand freewheel w/56t engine sprocket. Your 72t 8mm sprocket should bolt right on. The Chinese pocket bike left-hand freewheel threads on the left-side of the hub. Then the engine sprocket simply bolts onto it.
Be sure to get the left-hand freewheel. The pocket bike freewheels are available in left-hand thread AND right-hand threads.
gera and MR JOHN, please do more research before buying parts.
gera, I'd recommend a used, top-quality bicycle with front suspension. You could get one for about $100 if you shop well, maybe at yard sales or on craigslist.org
I purchased a near-new late-model DIAMONDBACK RESPONSE bike for $125. It was the perfect bike for me.
Most rear hubs accept a right-hand freewheel and a sprocket/cassette. This custom hub accepts all the stuff on the right side, and a left-hand freewheel w/56t engine sprocket. Your 72t 8mm sprocket should bolt right on. The Chinese pocket bike left-hand freewheel threads on the left-side of the hub. Then the engine sprocket simply bolts onto it.
Be sure to get the left-hand freewheel. The pocket bike freewheels are available in left-hand thread AND right-hand threads.
gera and MR JOHN, please do more research before buying parts.
gera, I'd recommend a used, top-quality bicycle with front suspension. You could get one for about $100 if you shop well, maybe at yard sales or on craigslist.org
I purchased a near-new late-model DIAMONDBACK RESPONSE bike for $125. It was the perfect bike for me.
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That freewheel seems good. I think it would also be more reliable than attaching to the spokes right? Does that one fit the 72T sprocket?
Heaven I wish you could have told me earlier. I spent so much money on the actual motorized bicycle sprockets and bicycle attachment sprocket kit for nothing lol.
Heaven I wish you could have told me earlier. I spent so much money on the actual motorized bicycle sprockets and bicycle attachment sprocket kit for nothing lol.
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