Victa go kart info needed.

[OzFab]

Guys, do the maths:

3/8" = 9.5250mm
11" = 279.4mm
84 teeth x 9.5250mm = 800.1mm circumference
800.1mm / pi = 254.68mm (or close enough to 10") radius
That leaves you 1/2" or 12.5mm maximum ground clearance

Using the same formula, a 72t has a raduis of 218mm, giving you around 25mm ground clearance & still a decent ratio

 

[landuse]

Maths is not my strong suit

 

[James.Ait.2013]

with a 78 tooth rear sprocket I should have around 40mm clearance and a gear ratio of 6.5. and thank you to all the guys for putting up with my questions, and I best be off to get my father motivated to help me with a chassis to put my motor on! thank you .

 

[OzFab]

with a 78 tooth rear sprocket I should have around 40mm clearance and a gear ratio of 6.5. and thank you to all the guys for putting up with my questions, and I best be off to get my father motivated to help me with a chassis to put my motor on! thank you .

How did you figure that out? If an 84t gives you 12mm & a 72t gives you 30mm, how can a 78t give you 40mm?

Edit: Ah, I know what you did or, more to the point, what you didn't do; you didn't divide the difference:

The size difference between the tyre & the sprocket is 40mm overall; you need to halve that much to get the ground clearance

 

[James.Ait.2013]

yeah, I missed a step there, I forgot to halve it. but I do think that ratio should be the right one for me. until i drive it anyway.

 

[landuse]

yeah, I missed a step there, I forgot to halve it. but I do think that ratio should be the right one for me. until i drive it anyway.

20mm is mighty close to the ground!! Are you going to be riding on tarmac only?

 

[James.Ait.2013]

on gravel, and maybe a go kart track near where i live. (I live 10 minutes from a go kart club) should i look to gear it down, or should i go for a bigger tire? i have 11 inch an unlimited source of slicks (I play squash with a guy that races karts at the top level, so new tires every meet. best idea in a long time )

 

[landuse]

If you get bigget tyres you will have to gear it down anyway. I would use a jackshaft. 20mm of clearance is nothing. You are going to be hitting things all day long. What size tyres have you got now, and what size would you het if you did go bigger

 

[James.Ait.2013]

I have 11 inch tires now. could i get a 10 tooth front sprocket, rather than a 12 and I can have a 65 tooth rear rather than a 78? surely that would make a big difference? It is still the same gear ratio? But the problem is can I get a 10 tooth front sprocket to fit my clutch?

EDIT: just crunched some numbers, i would have nearly 6cm clearance from sprocket to the ground, would this be good enough? i really dont want to have go jackshaft as i have limited access to go kart parts, and I'm a real Scottish tight a**! so I'm not too keen to buy extra parts that i cant build, or have lying around.

 

[landuse]

I have 11 inch tires now. could i get a 10 tooth front sprocket, rather than a 12 and I can have a 65 tooth rear rather than a 78? surely that would make a big difference? It is still the same gear ratio? But the problem is can I get a 10 tooth front sprocket to fit my clutch?

EDIT: just crunched some numbers, i would have nearly 6cm clearance from sprocket to the ground, would this be good enough? i really dont want to have go jackshaft as i have limited access to go kart parts, and I'm a real Scottish tight a**! so I'm not too keen to buy extra parts that i cant build, or have lying around.

I just crunched the numbers now as well, and I got 4cm clearance. I am not too sure where you got the 6 from.

11" = 279.4mm

65T * 9.525 = 619.125 mm (circumference)
619.125/pi = 197.0736 mm (radius)
279.4 - 197.0736 = 82.3263
82.3263/2 = 41.1631 mm ground clearance

As for the 10T #35 clutch, I don't think you are going to find one. Fitting 10 teeth round onto a clutch at a 3/8" pitch is I think impossible. If you can find one, you should be fine, because the ratio hasn't changed.

 

[James.Ait.2013]

I just crunched the numbers now as well, and I got 4cm clearance. I am not too sure where you got the 6 from.

11" = 279.4mm

65T * 9.525 = 619.125 mm (circumference)
619.125/pi = 197.0736 mm (radius)
279.4 - 197.0736 = 82.3263
82.3263/2 = 41.1631 mm ground clearance

I really should stop this idea with doing the maths in my head, I'm just making an idiot of myself.

Would 40mm be enough ground clearance? I may be able to buy another clutch that is 10 tooth at the front ( the reason I got a 12 is it was a trade for a good condition powertorque engine for the clutch) money is tight right as of now, as I have to pay rego on my dirtbike, as well as keeping it maintained. But how much will a 10 tooth clutch cost in Australia if I cannot buy one through GA spares at work? I have looked on eBay but most are around $60-70 for a clutch alone. That's is nearly the price of my metal for my go kart frame! This hobby is really turning out like it might hurt the pocket a bit in the end!

 

[landuse]

I really should stop this idea with doing the maths in my head, I'm just making an idiot of myself.

Would 40mm be enough ground clearance? I may be able to buy another clutch that is 10 tooth at the front ( the reason I got a 12 is it was a trade for a good condition powertorque engine for the clutch) money is tight right as of now, as I have to pay rego on my dirtbike, as well as keeping it maintained. But how much will a 10 tooth clutch cost in Australia if I cannot buy one through GA spares at work? I have looked on eBay but most are around $60-70 for a clutch alone. That's is nearly the price of my metal for my go kart frame! This hobby is really turning out like it might hurt the pocket a bit in the end!

I am just not too sure if you will get a 10T clutch in a #35. I know you can get in a #41 size. Just make sure that you have the same pitch sprockets on clutch as well as axle

There are a couple of Aussies on the forum, so maybe one of them can point you in a better direction than I can

 

[James.Ait.2013]

Thank you, I'm sure Fabroman would have some idea. I might shoot him a PM.

 

[landuse]

Thank you, I'm sure Fabroman would have some idea. I might shoot him a PM.

Good idea

 

[OzFab]

I have 11 inch tires now.

If you're using standard 5" go kart wheels, the tallest tyre you can get is 11"

As for the 10T #35 clutch, I don't think you are going to find one. Fitting 10 teeth round onto a clutch at a 3/8" pitch is I think impossible.

Correct, it's physically impossible to fit 10 #35 teeth around a 3/4" clutch

Did you both miss this point?

a 72t has a raduis of 218mm, giving you around 25mm ground clearance & still a decent ratio

 

[James.Ait.2013]

If you're using standard 5" go kart wheels, the tallest tyre you can get is 11"



Correct, it's physically impossible to fit 10 #35 teeth around a 3/4" clutch

Did you both miss this point?

no, I did see that. I just was still worried about ground clearence, as with a #35 sprocket is really thin, one rock at high speed will end the fun for the day. But you guys would know better than me, would 25mm be enough clearence?

 

[OzFab]

I'm using a 60t with 10" tyres which gives me around 30mm ground clearance & a 5:1 ratio off a modified GX160. I get great acceleration & an, as yet, unmeasured top speed but, it's quick.

Having said that, to get the same ground clearance with 11" tyres, you need a 68t sprocket which gives you a 5.66:1 ratio. Given that a Victa 160 may or may not (but, being a 2 stroke, it probably doesn't) have the same torque curve as my engine, you may find performance to be a bit different.

The bottom line is, it's a matter of trial & error; as a point of interest, it cost me 3 sprockets to get the desired setup...

But how much will a 10 tooth clutch cost in Australia if I cannot buy one through GA spares at work? I have looked on eBay but most are around $60-70 for a clutch alone(

Can you get a clutch through them? If so, at what price?

Alternatively, I found it cheaper to import a clutch; for the price of a locally sourced clutch I bought a MaxTorque clutch plus chain plus shipping

 

[sideways]

Given that a Victa 160 may or may not (but, being a 2 stroke, it probably doesn't) have the same torque curve as my engine, you may find performance to be a bit different.

The Victa has slightly less torque but it peaks 500rpm lower than a standard GX160.

Alternatively, I found it cheaper to import a clutch; for the price of a locally sourced clutch I bought a MaxTorque clutch plus chain plus shipping

This x 1 million. Though pulley tensioner clutches are where it's at.

 

[James.Ait.2013]

It cost my work ( a mower shop, that mainly deals with GA spares. ) $67 for a clutch and shaft adapter. They ordered it at monday 9:30am and it was there Tuesday at 4:30pm. So not a bad turn around. And thank you fabroman, sprockets are only $30 each so if I need to buy three of them to find the right gear that's fine. And would people buy second hand sprockets? If so ill just flog the ones I don't need off to recoup some of the cost.

 

[OzFab]

Check out Cut Price Racing, Paul is a member here. I got my sprockets for $25 each delivered.

He has a great deal ATM