Old Kart, scaling help!

K

K.johnson3130

Member
TL;DR: looking for general starting point for scaling a JR1 class chassis. Unknown year for chassis (possible 97-98 Spector Fugitive???). Details below:

Class: JR Sportsman 1 @ 265Lbs (Clone mtr)
Track: Bullring (Ocala, FL) 1/4 to 3/8, low banking, clay track with no prep (just water, and smoothing)

I grew up racing and we dusted off our karts from 28ish years ago to see if it's something my son would like to do. My Grandfather so all the racing knowledge has been lost. I was way to young to really understand what was happening back then. We have little to no data on the Kart so no reference for a general starting point. I'm new to scaling but understand the concept and would like to get my son a fighting chance.

We have run 3 weeks now and he is fast on the front/back stretch but fights the car a lot and loosing lots of momentum, when he spins, it's coming out of 1 and 3.

Current set up scaling:

LF: 57lbs @ 21.4% | RF: 50lbs @ 18.7%
LR: 83lbs @ 31.2% | RR: 76lbs @ 28.5%

Left: 140 lbs @ 52%
Cross: 133lbs @ 50%
Nose: 107lbs @ 40%

Any general help would be greatly appreciated!

*** Disclaimer: Driver is very new and definitely learning how to race but does seem to be fairly good for a new driver. I owe him a better set up, he is fighting the car a lot in the corners.
 

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flattop1 said:
I would want more nose . probably a different Lft rear tire .a 6/6/6
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Thanks, what percentage are you thinking for the nose? Wouldn't more nose make the rear end loose?As for the LR can you explain what you mean by 6/6/6?

Tire set up is: LF: 10.5 x 4.5 x 6 | RF: 12 x 8 x 6
LR: 11.5 x 6 x 6 | RR: 12 x 8 x 6
 
flattop1 said:
6 or 6.5 wide. 45%.
What's the driving/handling problem?
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He seems very loose to me. He is fighting the car to get it to the bottom entering into 1& 3. Part of that is the lack of experience. He is driving too hard into the corner (late off the gas). But as he comes out of 1 around the apex going into 2 he is spinning a lot. It's generally always there (3/4 as well).

The longer the race goes on the more it happens (poor tire prep??, still learning there too). He knows how to counter steer pretty well, it looks like the rear , is sliding out more than him turning down on the apex.

Hope that helps explain it.
 
Last edited by a moderator:
Not enough nose, too much rear can make a kart spin out easier once traction is broken. And tires are the reason it gets worst as race goes on, and theres many variables there as to the reason.
Ive won at this track many times but thats been a while back, now i just have customers there but if you would like to talk tires some, just give me a shout.
 
K.johnson3130 said:
TL;DR: looking for general starting point for scaling a JR1 class chassis. Unknown year for chassis (possible 97-98 Spector Fugitive???). Details below:

Class: JR Sportsman 1 @ 265Lbs (Clone mtr)
Track: Bullring (Ocala, FL) 1/4 to 3/8, low banking, clay track with no prep (just water, and smoothing)

I grew up racing and we dusted off our karts from 28ish years ago to see if it's something my son would like to do. My Grandfather so all the racing knowledge has been lost. I was way to young to really understand what was happening back then. We have little to no data on the Kart so no reference for a general starting point. I'm new to scaling but understand the concept and would like to get my son a fighting chance.

We have run 3 weeks now and he is fast on the front/back stretch but fights the car a lot and loosing lots of momentum, when he spins, it's coming out of 1 and 3.

Current set up scaling:

LF: 57lbs @ 21.4% | RF: 50lbs @ 18.7%
LR: 83lbs @ 31.2% | RR: 76lbs @ 28.5%

Left: 140 lbs @ 52%
Cross: 133lbs @ 50%
Nose: 107lbs @ 40%

Any general help would be greatly appreciated!

*** Disclaimer: Driver is very new and definitely learning how to race but does seem to be fairly good for a new driver. I owe him a better set up, he is fighting the car a lot in the corners.
Click to expand...
When I saw the track I held off on responding Till Earl responded , Now that he has it makes tire advise to you VERY , VERY , VERY , SIMPLE , and I can tell you with 110 % confidence it's the BEST advise anyone could give you to solve your lack of tire knowledge, that will speed up the process of where you wish the kart to be for your Son. Since Earl has responded Take the man up on his offer and call the man up, Have a pen and bad be prepared to give details ask questions take notes , Now here's the tough part DO EXACTLY WHAT THE MAN TELLS YOU TO DO !! " WHY " That Grandfather that had all the experience and knowledge that you thought was lost and gone forever, has just been put back into your racing program and his name is Earl . Plus the added perks his prep line is PROVEN, His Integrity and customer service is second to NONE, He's got the experience and is full of knowledge and not only with tires, Before you even make the call consider yourself his NEW but very loyal customer .
*** Disclaimer *** Remember your's here because Earl getting you on the right set of tires and prep is the Easy part , battling through the growing pains with your little driver there will be the tough part , because you have very little control over how long it will take him to adjust as a driver , Be Patient don't find yourself getting competitive STUPID , be aware your going to have guy's approach you at the track offering advise on most everything from tires, gearing, set up , that mean well but in the end it's still bad advise . Remember Accuracy without clarity is a waste of time !! And then you'll come across those that will tell ya anything just to sell ya something.
Now as far as the spinning out the numbers right now the RR is over loaded, your nose % age is to low , kart pushes he's got to add to much wheel to compensate for the push, add your sons lack of seat time = the spin out results .
You need a Balanced set up in that era kart , Left % age and cross % age need to be exactly the same , the Individual front static weight will be the same LF and RF will match, Then move weights around where the LF and the RR are with in 2 to 4 pounds of each other , Ideally you want the RR 4 pounds less than the LF ,
I can help you with set up advise so AFTER you contact Earl at So Co Tire Treatments get all his advise, remember that's not only tires ,
Then Shoot me a text first at 717 712 3437 Ken Identify yourself with your user name here on Bob's great forum, only so I know it's not a solicitor when you do call, If you could call when you can adjust the kart that would probably help you most.

Good Luck !!
 
racing promotor said:
When I saw the track I held off on responding Till Earl responded , Now that he has it makes tire advise to you VERY , VERY , VERY , SIMPLE , and I can tell you with 110 % confidence it's the BEST advise anyone could give you to solve your lack of tire knowledge, that will speed up the process of where you wish the kart to be for your Son. Since Earl has responded Take the man up on his offer and call the man up, Have a pen and bad be prepared to give details ask questions take notes , Now here's the tough part DO EXACTLY WHAT THE MAN TELLS YOU TO DO !! " WHY " That Grandfather that had all the experience and knowledge that you thought was lost and gone forever, has just been put back into your racing program and his name is Earl . Plus the added perks his prep line is PROVEN, His Integrity and customer service is second to NONE, He's got the experience and is full of knowledge and not only with tires, Before you even make the call consider yourself his NEW but very loyal customer .
*** Disclaimer *** Remember your's here because Earl getting you on the right set of tires and prep is the Easy part , battling through the growing pains with your little driver there will be the tough part , because you have very little control over how long it will take him to adjust as a driver , Be Patient don't find yourself getting competitive STUPID , be aware your going to have guy's approach you at the track offering advise on most everything from tires, gearing, set up , that mean well but in the end it's still bad advise . Remember Accuracy without clarity is a waste of time !! And then you'll come across those that will tell ya anything just to sell ya something.
Now as far as the spinning out the numbers right now the RR is over loaded, your nose % age is to low , kart pushes he's got to add to much wheel to compensate for the push, add your sons lack of seat time = the spin out results .
You need a Balanced set up in that era kart , Left % age and cross % age need to be exactly the same , the Individual front static weight will be the same LF and RF will match, Then move weights around where the LF and the RR are with in 2 to 4 pounds of each other , Ideally you want the RR 4 pounds less than the LF ,
I can help you with set up advise so AFTER you contact Earl at So Co Tire Treatments get all his advise, remember that's not only tires ,
Then Shoot me a text first at 717 712 3437 Ken Identify yourself with your user name here on Bob's great forum, only so I know it's not a solicitor when you do call, If you could call when you can adjust the kart that would probably help you most.

Good Luck !!
Click to expand...
Are my eyes playing tricks on me or is that a sprint seat on that kart? And do you recommend that much weight on 1 bolt through the seat? Seems like it would pull through the fiberglass. Not trying to criticize but those 2 things pop out to me as soon as I see the pics. But to the OP you are in good hands with Ken and Earl. Better get a tape recorder so you can register the amount of knowledge given to you.
 
Kinda looks like a g-man . Good catch though.
A properly fitting seat is a must. Driver bouncing around hinders control.
 
Thanks everyone @SoCo Tire Treatments I'll definitely reach out here soon. I have a lot to learn in all areas of the sport lol tire game I know is a big one!

For the upcoming race I think I'm going to try to get things closer to

Last race set up: Left: 52% | Cross: 50% | nose: 40%
Friday set up: Left: 54% | Cross: 55% | nose: 46%

I appreciate everyone, and please let me know if you think these numbers are way off. My thoughts is this should be a significant difference and give me a place to determine if I'm getting better or worse with the set up.
 
K.johnson3130 said:
Thanks everyone @SoCo Tire Treatments I'll definitely reach out here soon. I have a lot to learn in all areas of the sport lol tire game I know is a big one!

For the upcoming race I think I'm going to try to get things closer to

Last race set up: Left: 52% | Cross: 50% | nose: 40%
Friday set up: Left: 54% | Cross: 55% | nose: 46%

I appreciate everyone, and please let me know if you think these numbers are way off. My thoughts is this should be a significant difference and give me a place to determine if I'm getting better or worse with the set up.
Click to expand...
With the new numbers did you notice the individual wheel weight's LF , RF, RR, LR , ?
 
K.johnson3130 said:
They are old 15° mounts. Is there something wrong with that? I have a newer mounts but I don't get the clearance I need, they are 0-5° at the most.
Click to expand...
Typically on a clone we tend to run anywhere from a 0-8 degree motor mount. In doing so the chain will be longer. The main reason the 15 degree mount was used with the flathead was clearance of the tank to the wheel. Also I see that your left side seat mount is located on the rear of the seat, we typically put that mount on the left side nerf bar spud.
 
K.johnson3130 said:
I did, we made some spindle adjustments to bring the cross up and that changed out individual tire numbers a pretty decent amount.

We ended on: LF: 57 | RF: 62 | LR: 86 | RR: 61
Click to expand...
some may argue but i dont really care about each tire weight when i scale the kart, i want my left, cross and nose where they need to be
 
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