Ask about gear ratios here!

[sideways]

It would seem every time I log on, someone is asking what gear ratio would be good for their kart so I though I would create this.

Please answer all of the questions below, if you don't, don't expect a useful answer.

We need to know

1. Tyre diameter, as in, the actual diameter, not just "oh about 10 inches".
2. What engine you have.
3. What RPMs your engine is capable of.
4. What kind of clutch/drivertrain you have.
5. If you have a jack shaft.
6. Current number of teeth on clutch or torque converter (if applicable).
7. Current number of teeth on axle or jack shaft sprocket (if applicable).
8. Weight of kart including rider.
9. What terrian the kart is used on.
10. What kind of top speed you are expecting.

This is a good read up on gearing for those unfamiliar with it.

Also, the diygokarts speed calculator is handy to play around with whilst figuring out what gear ratio you want.

Please keep in mind, we may say your aims are quite unrealistic, If your trying to get 50MPH out of a 400LB kart with a 6.5 clone and centrifugal clutch that's only driven off road then we're going to say it's not going to work.

Ask away peoples.

Thanks

Hayden

 

[HellSpawn]

sticky maybe?

 

[Russ2251]

This is a far better calculator.
Absolutely correct down to a single tooth.

 

[landuse]

This is a far better calculator.
Absolutely correct down to a single tooth.

I have added this link to the sticky in the FAQ section for helpfull links

 

[sideways]

sticky maybe?

Would be good, otherwise this thread wont get posted in too much.

This is a far better calculator.
Absolutely correct down to a single tooth.

Thanks Russ. I'm sure if we ask Rob nicely he could modify our current one.

 

[Doc Sprocket]

It would seem every time I log on, someone is asking what gear ratio would be good for their kart so I though I would create this.

Please answer all of the questions below, if you don't, don't expect a useful answer.

Yes! I especially like it when you devote a pile of time and effort to trying to get someone sorted out, and they can't be bothered providing the required info.

 

[qnzkyat96]

It would seem every time I log on, someone is asking what gear ratio would be good for their kart so I though I would create this.

Please answer all of the questions below, if you don't, don't expect a useful answer.

We need to know

1. Tyre diameter, as in, the actual diameter, not just "oh about 10 inches".
2. What engine you have.
3. What RPMs your engine is capable of.
4. What kind of clutch/drivertrain you have.
5. If you have a jack shaft.
6. Current number of teeth on clutch or torque converter (if applicable).
7. Current number of teeth on axle or jack shaft sprocket (if applicable).
8. Weight of kart including rider.
9. What terrian the kart is used on.
10. What kind of top speed you are expecting.

This is a good read up on gearing for those unfamiliar with it.

Also, the diygokarts speed calculator is handy to play around with whilst figuring out what gear ratio you want.

Please keep in mind, we may say your aims are quite unrealistic, If your trying to get 50MPH out of a 400LB kart with a 6.5 clone and centrifugal clutch that's only driven off road then we're going to say it's not going to work.

Ask away peoples.

Thanks

Hayden

whats up, dont have an answer for questions 1,4,6,7. was hoping you can help me chose what i should get for those. engine is a 16hp duromax 3600rpm. no jackshaft, weight with me is between 380-400lbs, not sure cause i dont have tires and sprockets and clutch. terrain will only be gravel, concrete. top speed im looking for is 35-45 mph. want a decent balance with acceleration and top speed. please reply. thanks!

 

[machinist@large]

whats up, dont have an answer for questions 1,4,6,7. was hoping you can help me chose what i should get for those. engine is a 16hp duromax 3600rpm. no jackshaft, weight with me is between 380-400lbs, not sure cause i dont have tires and sprockets and clutch. terrain will only be gravel, concrete. top speed im looking for is 35-45 mph. want a decent balance with acceleration and top speed. please reply. thanks!

Multiple postings with same questions.

 

[r_chez_08]

I would reccomend:
1. 15" tyres
4. 40 series torque converter if you can afford, if not a noram centrifugal clutch.
6. 10t
7. 40t
This will give you 40mph.
I reccomend you use 1/2" pitch no.40 chain.

 

[qnzkyat96]

I would reccomend:
1. 15" tyres
4. 40 series torque converter if you can afford, if not a noram centrifugal clutch.
6. 10t
7. 40t
This will give you 40mph.
I reccomend you use 1/2" pitch no.40 chain.

thanks man, and will a #35 chain work? cause i already found parts for 35 chain. if i use the 40 will there be a difference in speed/acceleration? also, it won't take forever to reach 40mph with the 4:1 ratio? thanks

 

[r_chez_08]

if you use the torque converter, it wont take as long to reach 40.
you have a 16hp. it should get there ok.
You could use 35, but its not as strong

 

[qnzkyat96]

if you use the torque converter, it wont take as long to reach 40.
you have a 16hp. it should get there ok.
You could use 35, but its not as strong

ok thanks, but with the torque convertor, won't i need more sprockets?

 

[r_chez_08]

For the torque converter you will require a jackshaft, bearings and a sprocket.

 

[MisterRoboto]

22
predator 6.5 212cc.
3600
would like to know what clutch sprocket i should try to get thinking 10t sprocket do they make 9t 41 chain
no jackshaft
no clutch yet, no money for torque converter at this time.
40t axle sprocket
approx 380-400
slightly bumpy yard
40 on driveway and dirt roads

 

[hurlflink]

1. 19.5
2. blue gx200 clone
3. no governor so around 5000
4. waiting for delivery of a 30 series torque converter
5. no
6. 10
7. thats what i want to know
8. approx. 300lbs
9. off road fairly smooth backyard track
10. hoping for approx 40mph give or take a few(looking mostly for acceleration)

 

[juvius]

ratio question

my clutch was running hot and was slightly smoking. it had hardly any take off power. i just bought this cart. I want to know if i need smaller tires or something. (i can change sprockets, but would rather just replace wheels if possible if needed). it's just something for the kids to ride around on (sometimes me).

1. 17.5 inch rear tires.
2. 8hp briggs and stratton w/ elec. start (older unknown model #)
3. I don't know the RPMs (can't find a manual since i don't know the model)
4. Centrifical clutch
5. no jack shaft
6. 12 teeth on clutch.
7. 72 teeth on axle.
8. kart weight around150lbs. riders: 80lbs, 120lbs, 230lbs.
9. mostly concrete.. sometimes yard.
10. no top speed in mind. just want it mostly for kids to enjoy.

 

[landuse]

I would say that your tyres are way too big for your kart. You have a 72/12 = 6:1 ratio. That is probably too high for your clutch with those large tyres.

Do you know if the person you bought it from rode it around with those tyres, or if they were changed before you got it. If it were me, I would probably try changing the tyres for smaller tyres. You could also go for a larger axle sprocket (probably not too practical due to the large size), or a smaller clutch sprocket.

Try smaller wheels first though

 

[juvius]

I would say that your tyres are way too big for your kart. You have a 72/12 = 6:1 ratio. That is probably too high for your clutch with those large tyres.

Do you know if the person you bought it from rode it around with those tyres, or if they were changed before you got it. If it were me, I would probably try changing the tyres for smaller tyres. You could also go for a larger axle sprocket (probably not too practical due to the large size), or a smaller clutch sprocket.

Try smaller wheels first though

thanks. I will be getting smaller tires next weekend.... i'm going to go ahead and get a new clutch for it while i'm at it. i have no idea how old the one on is and how much abuse it been under. The tires on the rear look pretty new.. he gave me the old rims/tires which were actually bigger. i'll update the thread with the results once i get the new wheels and clutch put on....

 

[Paij]

1. 18 inch diameter 8.5 inches wide
2. 6.5 HP Harbor Freight Engine
3. Umm not really sure how to find this out but it is stock
4. Max torque 30 dollar clutch
5. No, solid live axle
6. 12 teeth on clutch
7. 72 teeth on axle
8. Guessing about 300 pounds
9. Off road
10. maybe 20 mph


So my problem is that we just renovated this cart so that it now has 18inch tires in the back compared to 13 in wheels and the axle in the back is now connected. After these renovations the cart does not want to start at all, but will go decently fast after it has some run up time. I want to be able to drive this off road on our land so I need to go slow, but im pretty sure my clutch is burning up as it smokes bad after I drive it around slowly.

Does anyone any links to torque converters and how they work/ how to attach them to my cart? I am looking at maybe the comet 20 seires or maybe the comet 30 series but don't really see a difference. Also I am completely lost on what gearing I will need.

Thanks

Paij

 

[dvdglmn]

is there any equation or estimate or any way to tell how long it will take to reach your top speed using that info without physically doing it??
say on a perfectly flat asphalt road...