HOW TO CALCULATE GEAR RATIO and TOP SPEED on MINI BIKE or GO KART

In this video you will learn how to calculate gear ratio and top speed of your DIY project with a chain drive.
Thanks for watching!

[@Chives1797]

Gear ratios are even now still a trouble, but this video made it click unlike any other video. Thank you my friend. You will make my first build even more sucsessful

[@archivestereo]

This is really helpful and you explain it perfectly. Thank you!!!!

[@roystoys3239]

Wonderful video (informative and well done). Exactly what I needed to know. Thanks!

[@KH-hj8nw]

Went from completely not knowing now it seems very easy to calculate, Thank You!

[@GabsFZago]

Absolutely perfect! This is exactly what I was looking for

[@OkayBuilds]

@Gabs F. Zago thanks! Glad my video helped!

[@JUNXRCZ]

Super helpful ! my buddy helped me put a predator 212 on my sons Coleman kt196, he also bypassed the jackshaft and until watching this I couldn’t understand why my torque went down,take off has been crazy slow where as the stock setup it actually had a pretty decent launch. I’m guessing there was additional gear reduction in the stock setup.

[@RamiroBerumen510]

Thanks for sharing your wisdom brother helped me a lot!!

[@OkayBuilds]

@Ramiro Berumen, no problem, glad it was helpful!

[@brookmorgan6627]

Thanks for the video and explanation! I'm building a time machine and wasn't sure of the gear ratio of the drive converter. This really helped! I'm gonna SMASH the like button.

[@OkayBuilds]

@brook morgan, I'm glad that my video was helpful for you! I appreciate you commenting and liking!

[@Breslinmusic]

Brilliant, Thank you 🙂

[@xxzeroxgamerxx-6735]

Thank you very much I was trying to figure out why my mini bike for the power behind the motor was going so slow and just by putting a 20t sprocket on my torque runner shaft I could be doing 82.01 vs the 38 sum I was going

[@OkayBuilds]

Glad my video helped!🙂

[@RamiroBerumen510]

82 mph? Wtf

[@MrXlthegreat]

Where did u find the 20t sprocket I’m running a 212 with tons of mods and after watching this video I definitely gotta change mines out I have the Juggernaut on my torque converter I need a bigger one please let me know thanks

[@cleanname4439]

@@MrXlthegreat just get a smaller rear

[@-iIIiiiiiIiiiiIIIiiIi-]

Really good video.

[@soundgamer1157]

Absolutely the goat thank you so much 👍

[@anthonypineda3388]

Youre awesome, thank you so much and keep up the hard work

[@Sussy-hotdog]

Consider engine size, tire size, torque converter, jackshaft and axle sprockets. Is 5:1 on a stock 6.5 hp predator with 18 in wheels ideal, or would that 5:1 ratio work every better on a stage 1 predator at 8.8 hp and 16 inch wheels. You're looking for that optimum sweet spot .... strong torque out of the whole, yet a decent top speed as well. Experience will tell you how to modify the ratio, and the best combination needed to achieve it. Sometimes you've gotta just keep swapping parts until you get it just right. No biggie. That's how you learn.

[@PunkCoverMoose]

Great explanation!

[@OkayBuilds]

Thanks!

[@patrickc.5441]

You explained it well, thanks! I'm going with a TC direct mounted to a jackshaft that's turning a 10T to a 39T axle sprocket with 22" tires. All this pushed by a 420cc with a couple of mods. I've got great expectations for this build. Again TY!

[@OkayBuilds]

@Patrick C, thanks! 🙂 That's gonna be a rocket! Good luck with your build!

[@patrickc.5441]

@@str8xrippin That's too fast! Make sure you get speed rated tires. Good luck on your build

[@GeorgeHasher-mv9jp]

Wat about a 224 cc with torque converter ten tooth on the tav and 38 rear tooth and 20 inch tires

[@Sebi076]

thanks for the info.

[@danbolderoo5669]

This is the exact video I need!

[@codyswilley]

Just did the math on the manco dominator I'm building. I'm running a 10T on the motor and a 27T on the axle with 14" tires and mine will run somewhere in the 55mph range. Way to fast for me. Thank you very much. Idk if I will change mine or not. Itll be nice having that extra speed. May come in handy on a rainy day lol

[@beaubrummelmotorizedbicycles]

Thanks so much for this video, it is the easiest, simplest explanation I've seen on gear ratio's. I shared it on my facebook group, about motorized bikes. The members over there have a hard time understanding gears, ratio's, CVT torque converters and how to figure it out. I hope they watch and learn and subscribe to your informative channel.

[@OkayBuilds]

@beau brummel, thanks for sharing my video, it is helps my channel alot! Hopefully this video will be helpful for your guys!🙂

[@hanafiismail7456]

Thanks.. Start thinking, what should to do..

[@bonezy5850]

Thank you, I'm building and electric mountain board and this was extremely helpful.

[@OkayBuilds]

@Bonezy glad my video was helpful for you! I wish you succes in your build!

[@MrTom-ex8ph]

That cool af @bonezy

[@jayspice4987]

Thank You So Much For This. I was unsure of the gear ratio of the cvt(torque converter) and you saved me so much time on my project. U just got a subscriber.

[@OkayBuilds]

@Jay Spice I'm glad my video was helpful for you, and I appreciate you subscribing!

[@Sparkanen]

@@OkayBuilds is it possible to create last for in metrics? :D

[@josephbarnes1178]

Just what i was looking for

[@GARDENBOIKENNELYARD]

👍🏾 excellent

[@lexpro2239]

Pi* great video, thank you for your help!

[@OkayBuilds]

@Lex Pro, thanks, glad my video helped you!🙂

[@merinofarmeragriculturewor4623]

Hey mate got a question iv got a atv bike the front drive gear from motor is 10 to 11 into gear box forward/back .. gear box to rear is 19 to 40 just need help to work out the gear ratio & speed it will do .. cheers Chris

[@SKITYSTUDIOS]

Cheers mate

[@mr.turtle2728]

Great video, but I have one question if anyone could help me. I am still wondering what gear ratio I should use for a 6 hp engine with 15 inch tires, that allows the machine to accelerate easily and have a decent top speed?

[@alpharomeo5123]

👍 very helpful

[@OkayBuilds]

@Alpha Romeo, I'm glad to hear that!🙂

[@splish6118]

So i got a brand new coleman ct100u. I have no idea what the stock sprockets are but its a 99cc 3hp engine. What would be the best gear ratio for top speed?

[@tonytuesday8339]

Thoughts on 15 tooth clutch and 60 sprocket or 53 sprocket

[@shebrightmechanics4033]

How would you do it with pullys

[@mariametko]

What's the best drive and driven sprocket combination so I can solve the over slack in the rear chain to my Coleman ct200uex ? I'm finding out that this causes bearing problems to the driver bearing. Thanks. Great video.

[@OkayBuilds]

@maria metco, if your chain is over slacked and you are ok with the top speed of your mini bike, you might look into switching to a better quality chain, your problem right now is that your chain is stretched, those mini bikes don't come with the best chains, so if you upgrade to a better chain that will solve your problem, but if you will go the sprocket changing way it will affect your speed specs

[@jamesa6272]

If they taught me this in math class when I was kid I would of actually payed attention

[@TACOMASRT5]

Can you help me figure out my potential top speed? I am installing a 10 hp diesel engine that makes 20ft lbs of torque. I plan on using a 40 series torque converter and the larger pulley mounted on a jack shaft. I will have a 12 tooth drive sprocket and a 41 tooth driven sprocket. The tire is 25" tall

[@miguelpagansr6128]

What would your recommendation be? I’m looking to do a minibike build but I’m trying to keep it simple. I’d like to have some take off in city traffic and still have decent top speed, I know that this might be a long stretch but it’s worth asking. Thanks for the video and ride safe.

[@OkayBuilds]

@Miguel Pagan Sr, I would recommend going with a basic setup, that would be motor-torque converter-chain drive-rear wheel. Torque converter will give you a wider range of gear ratio, that means you can get a good take off and a decent top speed. You can calculate that with the formula in my video. Good with your build!

[@miguelpagansr6128]

@@OkayBuilds thanks for the helpful video, another great video as always please keep them coming and ride safe.

[@OkayBuilds]

@Miguel Pagan Sr, thanks alot! Ride safe as well!🙂

[@miguelpagansr6128]

@@OkayBuilds hope you have more minibike videos out soon.

[@OkayBuilds]

@@miguelpagansr6128 yep, have some cool ideas for builds, but first I want to upgrade my garage a little, so there will be video coming soon about garage upgrades

[@anthonyreddy2834]

You explained this very well but What about the other factor? Weight of the Operator???

[@alohabobbylaguna1702]

i have a HONDA GX 270cc with a factory installed wet clutch 2/1 gear ratio any idea about gearing

[@Goomer]

Thanks, with just a clutch-jackshaft should you shoot for 6:1. Does the wheel diameter effect this. I was running 10-36-10-30 on 16 inch diameter tires.

[@OkayBuilds]

@Goomer, wheel diameter does not affect the gear ratio, it affects the speed, bigger wheel higher top speed

[@Goomer]

@@OkayBuilds Would you say a 6:1 Ratio is a good starting point? Thanks much.

[@OkayBuilds]

@Goomer, what engine do you have?

[@Goomer]

@@OkayBuilds Tecumseh HS50 5hp, old school.

[@OkayBuilds]

@Goomer, yes, 6:1 ratio looks good, with a 16 inch wheel and that motor you will get approximately 28-30 mph

[@base72588]

For those of us building track sleds this gets us close i think, BUT for Us the mini bike tire is basically our drive cog that drives the sleds track. Does the final speed change after putting a for example 121" track on the tire of the mini bike or in our case the drive cog?

[@OkayBuilds]

@base72588, I think you are right, because the track is just basically enlarges the foot print of the wheel

[@bassmachine00]

sorry what is pie 3.14 for? is standard measuring distance?

[@randyryanson1711]

I'm trying to use 2 small sprokets around the same size for a 212 powered 50cc atv it's not working at all idk if it's my centrifugal or my gearing it is just maybe 2 3 teeth bigger than my sproket on the crank shaft it dies as soon as I try and take off I did spend a hr and 20 mins tuning the carb and nothihg

[@landonthomas7470]

My question has always been whats a good gear ratio for decent acceleration and decent top speed over 45 for stage 1 with governor removal basic stage 1 I have seen some stage ones go 52 but I dont need like all of that so whats a good gear ratio 14 front and 62 back? No converter

[@OkayBuilds]

@Landon Thomas, that's a good question, but I think I won't be able to really answer it for you, because it depends on alot of factors like weight of the bike/rider, wheel diameter etc. even the area where you live in, whether it's flat or it's a area with bunch of hills that you will be taking your bike over...The only advice I can give you is if you want both decent acceleration and decent top speed, go with the torque converter!

[@jaydee659]

Just try the math he showed and plug in different ratios. Make sure to enter your correct measured tire diameter. Actually measure it with a tape. I got a stock ct200U, bypassed the gov to the outside hole and zip tied the gov spring, 30mph on GPS and motor is turning about 5700rpm according to the tach I just got, going to redo how the pickup wire is mounted tomorrow and recheck RPMs. It kept pulling and hasn’t acted like any valve float, I do have OMBwarehouse “box stock” valve springs to instal too, they are like a 10.5lb spring. Oh this is also with SunF AO20 tire, they are slightly shorter than the stock Coleman knobbies.

[@OkayBuilds]

@@jaydee659 totally agree!

[@Deucealive75]

@@jaydee659 If you are maxing out at 5700 RPM that is valve float. Put a torque converter on it and then the governor or valve float isn't even a concern. With a stage 1 kit you'll get 35* MPH without over rev on the stock rod.

[@corneliussianturi476]

I just still thingking, how much RPM for the engine to rotate torq converter to shift to 1:1 ratio?

[@Spacecruizer203]

i just bought a maxtorque 13tooth clutch for my bike it has a 65tooth rear what is that make my ratio or top speed its on a ducar212cc

[@Sherwood_95]

So I've gor a predator 212 on my mini bike it goes roughly 40 mph with the torque convertor. My rear sprocket is 31 tooth. So if I wanted to go faster what size sprocket should I use in the rear 🤔

[@OkayBuilds]

@dylan sherwood, you will need go with a smaller rear sprocket to go faster

[@Sherwood_95]

@@OkayBuilds it gets up quick as hell i just want a little more top end speed

[@Thirsty_5.0]

I have a mega moto 212, added juggernaut and it got slower. Built the motor and same results. What sprocket should I use for the juggernaut? Any help please!!

[@turkeyboyjh1]

What size tire, 50 tooth is what I’m running on mine I had a 10t clutch with a 20t Jack shaft and a 50t rear then went straight chain with 5-1 ratio and it hauls ass after 20mph but not power until then just recently installed the tav2 and no she gets with the program I’m also using a mild modded 224 max performance predator

[@MCscarfacematt]

to late test drive has been done and im down 15km/h which technically isnt a bad thing 52 on a golf cart is pretty sketchy especially since the brakes suck but im running through a reverse box and 40 series cvt with the stock rear end i was getting 52 at a 12:1 i have no idea what the reverse box reduction is but cvt out is 10T reverse box in is 12T reverse out is 10T axle is 65T. now i will be changing the cvt out and reverse in because buddy who put it together used 35 chain on 420 sprockets so its skipping under load

[@nayeemfarween8807]

Bro... what is the chain size needs for 125cc - 150cc bike, pls reply, thanks...

[@OkayBuilds]

@Nayeem Farween, I would go with a 420 chain, most of the mini bikes use this chain

[@nayeemfarween8807]

@@OkayBuilds Thanks bro...

[@talctothestrap5058]

I have a 212 mini bike with no torque converter, very new to this just bought the bike but I recently got a flat tire and I replaced the tube now my chain rubs against my tire, Not only that I was going about 15 mph on a dirt rode and my my chain popped off and broke. I have no Idea what to do about this and need help!

[@OkayBuilds]

@ Talctothestrap, you need to align the wheel properly, you want to make sure that the front and the rear sprockets are in line

[@bruceschmitz1984]

What about a 10 on front and 60 tooth on back with a torque converter

[@jppelletier5984]

Why not have a larger gear driving the driven gear at the wheel? Wouldn't that improve the overall top speed?

[@OkayBuilds]

@Jp Pelletier, you can, but I recommend using a torque converter, gives you a variable ratio

[@garrettlovell2769]

quick question, the higher the first number is the better the takeoff right??

[@OkayBuilds]

@Garrett Lovell, if you mean the bigger sprocket on the engine than the takeoff is worse, for better takeoff you need a smaller sprocket on the engine, that's if I understood you right

[@andrewdowney760]

Hi, if you could could please help me out. Just installed a 30 series on my coleman. So TC belt to 10 tooth spocket to 50 tooth rear sprocket. If I fallow you thats 1-5 ratio. Im getting 49mph at 4400 rpm. However thats at max throttle. Im not getting any higher rpm with load. Im only 130lbs aswell. The calculator says Im spot on but why the max of 4400 rpm with gov removed?

[@OkayBuilds]

@Andrew Downey, hi✋, is your governor removed or bypassed? The calculations look right, but it should turn a little bit faster. On the other hand you don't want to spin it to high without upgrading your flywheel and etc. (oem flywheels tend to explode at high rpm) I would swap the rear sprocket for a smaller one if you want to increase your speed.

[@andrewdowney760]

@@OkayBuilds 196cc, gov removed, billet fw/rod, mod2 cam, intake/exhaust done, 37 main jet, 18lb springs. Forum says the engine doesnt have enough power to go faster so I need to install a 8 tooth front sprocket to lower gear ratio. However you vid says dropping gear ratio will loose top speed and gain rpm and torque. What I want is speed. Red spring is on third hole. Im 130lbs. Im only getting 49mph at 4400 rpm

[@OkayBuilds]

@Andrew Downey, if you will install 8t front sprocket you will increase ratio, not lower it: 50÷8=6.25, that means you will loose top speed and gain torque. Less ratio - more speed,less torque. More ratio - less speed,more torque. If you want more speed you need bigger front sprocket or smaller rear sprocket. With the 8t front sprocket you will loose approximately 10mph.

[@andrewdowney760]

@@OkayBuilds apparently if the engine doesn't have enough power, it reaches its top rpm for power thus top speed. Its like starting a bike it 18th gear. It cant go fast because the motor doesnt have the power to spin faster. By dropping the gear ratio it will spin faster. If it spins faster with the torque converter it will go faster

[@OkayBuilds]

@Andrew Downey, give it a try and let me know the results, I'm curious now

[@jamesmoore5432]

How do you calculate the ratio into 1 number to plug it into the equation to put it into a calculator

[@OkayBuilds]

@James Moore, for example if your gear ratio is 10:1 you input only 10 into the equation, if 14:1 you input only 14 etc...hopefully I answered your question

[@REVNUMANEWBERN]

I'm putting a PREDATOR 8 HP (301cc) OHV Horizontal Shaft Gas Engine, using the centrifugal clutch on a lawnmower frame, can I NOT use a jack shaft and connect directly to a axle using a chain and have a decent speed where I can cut grass?? I don't need 20mph, is such possible and what axle size number of teeth do I need? I only need no more than 10 mph

[@OkayBuilds]

@Numa Newbern, you can probably get away without using a jackshaft, but the sprocket on the rear axle for 10mph will be huge, to calculate the amount of teeth on the rear sprocket I need to know your wheel diameter and the number of teeth on the clutch

[@tomtee4442]

I new their was a formula. motorized 4 stroke bike, jackshaft, 9 tooth torque converter, stock 50 tooth rear sprocket. Have a 66 rear tooth sproket going to try. Hope I'm not to rpm tached out at 12 mph max at times where I ride at for short periods. I want all take off and bottom end power hope 66 sproket is enough!

[@OkayBuilds]

@TOM TEE, good luck with your build! 🙂

[@williamedwards7315]

So I have a mini chopper that has a 12 tooth centrifugal clutch with a 35 chain running to a 72 tooth rear sprocket no governor 43 miles an hour maybe I want my bike to do 60 and have a number 40 chain what rear sprocket would I need if I got a number 40 10 tooth centrifugal clutch with a 40 chain what rear sprocket would give me the highest top speed but still be able to take off

[@OkayBuilds]

@William Edwards, there's more things to consider, engine rpm, wheel diameter etc. Use the formula and you will calculate what you need. Type of chain dosen't matter

[@williamedwards7315]

@@OkayBuilds I have a 14 tooth clutch that is new and I have just ordered a 60 tooth rear sprocket so hopefully that works

[@williamedwards7315]

@@OkayBuilds the gear go-kart calculator is telling me 14 tooth clutch to a 60t sprocket is only going to do 32 miles an hour

[@jimbo05551]

Hi I just bought a ct200u with a predator 212 engine I installed a new clutch 10t with rear sprocket 50t.the problem I'm having is that when I start it up it's great further pull start,but when I sit down to take off it moves slowly at full throttle.not sure what's wrong,do you think the clutch might be slipping or not fully engaged,because the clutch also gets real hot.please help anyone😰

[@OkayBuilds]

@Jimmy Marin, your problem is low gear ratio in your set up, a torque converter ($70) will fix your problem and will improve the takeoff as well as top speed

[@jimbo05551]

@@OkayBuilds ok,thanks would you be able to direct me to where I can get the parts I need to be able to ride?thanks

[@OkayBuilds]

@Jimmy Marin, no problem! Check this out on Amazon 212CC Torque Converter 6.5 HP 3/4" Go Kart Mini Bike Comet Clutch 10T 40/41 and 12T 35 Chain Predator Driver Pulley Replacement Set - 30 Series www.amazon.com/dp/B07S3TX4C5/ref=cm_sw_r_apan_i_GG27DMGQVHHGZT2Y4P12?_encoding=UTF8&psc=1 I got this one, works just fine!

[@jimbo05551]

@@OkayBuilds thanks!

[@WaTcHMySk1llz]

So every time I do this equation with the 4500rpm, 5.5 ratio and 5 wheel diameter it comes out to like 12mph. But my kart does WELL over that. What am I doing wrong here?

[@BlueOx2277]

Ok so I’m building a mini with a Predator 224, a 30 series torque converter, 10 tooth sprocket up front and a 72 tooth on the rear, running 21/7/8 tires. What kinda speed am I looking at here??

[@Deucealive75]

That would have nice low end. So much the bike may want to wheelie. For top speed it would just depend on what RPM you can get to. If you can get to 5K RPM you would be running high 40's MPH. Another thing about this. If you are using the stock torque converter get a yellow spring for the driven and put it in the tightest hole. This way the belt shift will be delayed under full throttle and you will get higher RPM during the belt shift. It's worth doing if you are interested in the best full throttle acceleration.

[@re9473]

So I recently brought a set of 38 inch tires and I have a 2009 F150 six speed transmission four-wheel-drive and I have no clue and trying to get as much advice as I can. If I should get 4.88 or 5.13 I don’t do any off-road at all but I definitely want to have nice low and torque I mostly only do city driving. If I go on the highway, it’s only an hour away to go to the beach. Opinions please

[@sabitchowdhury6067]

My 110cc 9bhp motor with 18 inch tyre reaches a max speed of 90kph... I want to reach 100 to 105 kph.. What should I do??!!

[@KhushalBadhan]

I wanted to use this video to share with friend to explain gears on bike. But then it started with freedom units with their cumbersome conversions.

[@mikefawcett7627]

What about weight factors for the top speed?

[@mikefawcett7627]

Great video btw

[@OkayBuilds]

@mike fawcett, weight factor is really important, for example, if you projected a top speed of 50mph but your mini bike has 1 hp engine, and its really heavy it will never reach that speed, even though the calculations were correct. In this case you need at least 5-6 hp motor to reach that speed. You should consider weight of the rider, power of your engine, mini bike weight, even before you start building it. Hopefully this makes sense

[@Sandeepkhattra54]

I have two gears,,,driver diameter 192driven diameter 112,,, we want add idler gear to make same speed of driver and driven,,, how can we calculate idler gear please help🙏

[@stevegraves2890]

The math is not adding up here (to me) in regard to the CVT (torque converter) setup. If your're utilizing a CVT, why is the jack shaft there? The "start" ratio may be 3:1 but variably changes on RPM of the engine (thus changing the ratio towards the 1:1 ratio quickly). The jack shaft in this example goes from 1:2 back to 2:1, essentially cancelling each other out. As well, there would be power transmission loss of effective power due to extra weight and friction.

[@robertcolaluca8882]

You added the start ratio and multiplied the end ratio that confuses me. 3 * 2 * 3 is 18 is there any way you can clarify this

[@OkayBuilds]

@robert colaluca, so 3 is the ratio of the torque converter, 2 is the ratio of the first chain link, and 3 is the ratio of the 2nd chain link, to get the final ratio you just multiply, hopefully that makes sense

[@ThatMinecrafter]

Good video except a predator 212 turns about 4685 with the throttle screw removed

[@OkayBuilds]

Thanks for letting me know!

[@ThatMinecrafter]

@@OkayBuilds your welcome thank you for taking your time to write a comment back to me most you tubers wouldn’t so I appreciate you

[@OkayBuilds]

@Red Devil Garage, thanks alot! Thanks for watching and commenting!

[@linloucfgouyg7436]

When I run chain I get 60 mph gps confirm. I can never get anywhere close running belt.

[@menamohib1063]

can you tell me formulae in Si system

[@OkayBuilds]

@mene mohib, you can use the same formula, the only parameter you need to input in standard system is the wheel diameter, you can convert it from cm to in, and then convert the end result from miles to kilometers, hopefully it will help you

[@marvthegreat1981]

I must have screwed up 😂 maybe someone else could figure it out. 1997 cr125 I would like to put a predator 212 with cvt. 12 tooth to 36 tooth and 26 inch tires. I came up with 97 mph😳😳that can’t be right 🧐

[@OkayBuilds]

@Marv The Great, your calculations were correct, with the setup you are planning to go with you will get over 90mph top speed, you need a smaller sprocket at the cvt(10t), and a bigger at the wheel. Good luck with your project!🙂

[@mafia.graham]

For some reason this didn’t work. My minibike does 38mph and I have a clutch with 12t and a rear sprocket with 75t. My rmps are at 4500 and my wheel base is 6inch. It says I will only do 10 mph which is not true.

[@JNC1973]

Hi, I'm too stupid to understand Math formulas so maybe you can do the math for me lol ? I have a 196cc Stock engine on my mini bike and I did add a 30 series Torque Converter to it along with Governor Bypassed and Stage 2 upgrade Kit. Right now I have an 11 Tooth Sprocket in the front and the Stock 50 Tooth in the rear and as it sits now it does 41 mph. Now I am thinking about changing the sprockets to gain a better top speed. Was going to change the 11 tooth in front to a 12 tooth and change the 50 tooth in the rear to a 48 tooth. If I did that then what would my final ratio be and how close to the 50 mph mark would I get ?

[@OkayBuilds]

@Jason Grisafi, your gear ratio will be 4:1 and the top speed will be around 50 mph

[@JNC1973]

@@OkayBuilds Thank You so much. That's what I was shooting for. :)

[@OkayBuilds]

@Jason Grisafi, no problem, good luck with your project!

[@akhilesh9969]

so weight doesnt come in??

[@OkayBuilds]

@Akhilesh Ezra, it does, for example, if you projected a top speed of 50mph but your mini bike has 1 hp engine, and its really heavy it will never reach that speed, even though the calculations were correct. In this case you need at least 5-6 hp motor to reach that speed. You should consider weight of the rider, power of your engine, mini bike weight, even before you start building it. Hopefully this makes sense

[@thunderf4]

Coleman CT200U 20mph? Ummmmm well I have worked on several CT200U and EX and 28-30mph is what I get stock with the governor still installed.

[@OkayBuilds]

@Randy G, I went with the spec rpm 3600, in real life they spin faster, that's why the top speed is higher. It is important to measure the engine rpm before calculating the top speed, to get accurate results

[@Fwv979]

I am having trouble calculating this pls help thx 6000÷25:4× it is a 14.5 in wheel (dont know the diameter)× 3.14 ÷12÷5280×60

[@OkayBuilds]

@GNE, it equals 10.34 mph, looks kinda slow, make sure you get all your parameters correct. For the wheel diameter just simply measure your wheel from end to end width a tape measure. According to your information you got a 14.5 overall wheel diameter.

[@Fwv979]

Ok maybe I was wrong with my calculations but thanks for helping anyways :)

[@Fwv979]

@@OkayBuilds the motor is going to run at 6000 rpm max the front sprocket is 12t and rear is 75t and tire is 14.5 D. Mabe that will be correct it is just a clutch sprocket

[@OkayBuilds]

@GNE, your gear ratio is 6.25:1, let's calculate 6,000÷6.25×14.5×3.14÷12 ÷5,280×60=41.39mph, that's better, good luck with your projects!

[@Fwv979]

@@OkayBuilds thank you so much, now I have an idea how fast my mini bike project is going to go.

[@K_Nasty]

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