Track Tac

Boy do I need some help

D

Dieselmoney92

Member
Okay guys I’ll start with a little back round of my self then get onto my problem... so I’m a third generation mechanic so I have a lot of mechanical aptitude my father and grandfather raced go karts dirt and asphalt from the 60s-80s with such chassis as the dart A bone to some later 80s margays and bugs ect so my father has a pretty good idea what we need too make a kart work my uncle also has a lot of experience for the early 2000s days his daughter ran a prowler chassis and won 2 dirt track championships back to back he has also given a lot of advice to get the kart right... so now for the problem my son is 6 he’s running a dirt track here in fl his kart is a mid 90s sks offset kart that has a track sealed 212cc predator with a red plate small pipe and stock air box we have to run Vega reds on the right 12-800-6s and Vega blues on the left 10.5-4.50-6 and a 11-6.00-6 15/66 gear and a shoe clutch we are going around the track about 35 mph with a very Consistent lap time 20.500-21.000 we can’t seem to find the speed that the other kids have they are running about 18.300-19.000 sec laps it seems like we have a horse power issue but the track owner looked of the kart advised me that my nerf bars were to tight my front nose cone was to tight and that those things were keeping the kart stiff and slowing us down my sons basically keeping the throttle pinned down the whole time he never has to lift so he’s going as hard as this kart will go my question is can we really be 2 secs slower for having a bound up kart? Or is this maybe not a kart issue as much as a hp issue I have two sealed engines and they don’t seem to turn as hard as the other guys do both engines one much newer then the other have the same lap time we were able to get down to a 20.0003 but the other guy ran a 18.344 so we are still off the pase almost 2 sec
 
Do you know the track size ? Do you know what your target RPM should be ? Do you have a tach and are you getting RPM readings ? If so what is your max RPM ? Is the 15/66 a gear rule everybody has to use ? Have you scaled the kart ? If so what are your numbers, including cambers ?
And YES if it's bound up real bad it could cause the difference.
 
"The nerf bars or too tight"?? I would be looking for a better source of information!

Mid-90s kart? There's been a lot of advances since then!
Do you have a tach? Have you scaled the kart? Have you dyno tested the engine? Give us some numbers if you have them.
There's somes really basic stuff that you should check; wheel bearings, front end alignment, chain alignment, Wheelbase alignment, etc. etc.
 
Dieselmoney92 said:
Okay guys I’ll start with a little back round of my self then get onto my problem... so I’m a third generation mechanic so I have a lot of mechanical aptitude my father and grandfather raced go karts dirt and asphalt from the 60s-80s with such chassis as the dart A bone to some later 80s margays and bugs ect so my father has a pretty good idea what we need too make a kart work my uncle also has a lot of experience for the early 2000s days his daughter ran a prowler chassis and won 2 dirt track championships back to back he has also given a lot of advice to get the kart right... so now for the problem my son is 6 he’s running a dirt track here in fl his kart is a mid 90s sks offset kart that has a track sealed 212cc predator with a red plate small pipe and stock air box we have to run Vega reds on the right 12-800-6s and Vega blues on the left 10.5-4.50-6 and a 11-6.00-6 15/66 gear and a shoe clutch we are going around the track about 35 mph with a very Consistent lap time 20.500-21.000 we can’t seem to find the speed that the other kids have they are running about 18.300-19.000 sec laps it seems like we have a horse power issue but the track owner looked of the kart advised me that my nerf bars were to tight my front nose cone was to tight and that those things were keeping the kart stiff and slowing us down my sons basically keeping the throttle pinned down the whole time he never has to lift so he’s going as hard as this kart will go my question is can we really be 2 secs slower for having a bound up kart? Or is this maybe not a kart issue as much as a hp issue I have two sealed engines and they don’t seem to turn as hard as the other guys do both engines one much newer then the other have the same lap time we were able to get down to a 20.0003 but the other guy ran a 18.344 so we are still off the pase almost 2 sec
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Don't worry about the dyno, or possible HP issues. It sounds to me like you have bigger issues. Your nerfs being tight is just an indication that the chassis is bound. Your nerfs should have some play in them to make sure the kart can flex around the track. If your nerf bars are tight, loosen them up. Most that I've seen only run 1 bolt in the side nerfs just to help with this.

Is the gear controlled by the rules? It sounds to me like you probably are a ways off of where you need to be. You say that your engines don't pull like the other guys. That means one of two things, you are either way over geared, or way under geared. If you can get a tach, and check with the engine guy to ask about best RPM range. You may also ask your fellow racers about what they have for gear for an idea. Here is what I would do if you don't have a tach, or can't get any help from anybody. Ask the Race Director for a lap or two by yourself. Make a change to something like a 63 OR a 69. Watch your stop watch. This will tell you if your gear is off. If he picks up speed, then you are headed the right direction. Keep going that direction whether up or down until the lap times start falling off, then go back a tooth or two. Obviously, if he loses speed you are going the wrong direction, make the same change but the opposite direction and do the same test. If you are tight on cash, see if someone will loan you gears until you find what you are looking for, this can save you $14 per gear.

Next thought, what are you doing tire wise? Are you prepping, and if so, what are you doing to them? With the low HP of the plate and predator, you will run a higher air pressure and in my opinion a harder tire to keep from getting the kart locked down. If adults are running 6psi, I would add at least a pound maybe more to help get some extra roll speed, less resistance, and get the kart to have corner speed.

Lastly, your class is 99.99% about maintaining momentum. Watch where your driver is running, how he handles the wheel, how he is getting into the corners, etc. Make sure he isn't cutting the entry too tight, and that he is letting the kart "float" on the exit, not chopping it off. Depending on where your son is mentally in terms of driving, watch NASCAR on TV and use it as a way to teach him about how to get around the corner. A lot of times at the track the young ones have a hard time focusing on what you are trying to teach them because they are just having waaay to much fun.

One other thing that may sound stupid but many have overlooked, make sure his seat isn't dragging the ground. Sure makes it hard to gain speed when he is dragging all around the track.

P.S. Make sure you keep it fun for the both of you. Nothing worse than seeing a father/son team fighting all of the time.
 
jaymancds said:
Don't worry about the dyno, or possible HP issues. It sounds to me like you have bigger issues. Your nerfs being tight is just an indication that the chassis is bound. Your nerfs should have some play in them to make sure the kart can flex around the track. If your nerf bars are tight, loosen them up. Most that I've seen only run 1 bolt in the side nerfs just to help with this.

Is the gear controlled by the rules? It sounds to me like you probably are a ways off of where you need to be. You say that your engines don't pull like the other guys. That means one of two things, you are either way over geared, or way under geared. If you can get a tach, and check with the engine guy to ask about best RPM range. You may also ask your fellow racers about what they have for gear for an idea. Here is what I would do if you don't have a tach, or can't get any help from anybody. Ask the Race Director for a lap or two by yourself. Make a change to something like a 63 OR a 69. Watch your stop watch. This will tell you if your gear is off. If he picks up speed, then you are headed the right direction. Keep going that direction whether up or down until the lap times start falling off, then go back a tooth or two. Obviously, if he loses speed you are going the wrong direction, make the same change but the opposite direction and do the same test. If you are tight on cash, see if someone will loan you gears until you find what you are looking for, this can save you $14 per gear.

Next thought, what are you doing tire wise? Are you prepping, and if so, what are you doing to them? With the low HP of the plate and predator, you will run a higher air pressure and in my opinion a harder tire to keep from getting the kart locked down. If adults are running 6psi, I would add at least a pound maybe more to help get some extra roll speed, less resistance, and get the kart to have corner speed.

Lastly, your class is 99.99% about maintaining momentum. Watch where your driver is running, how he handles the wheel, how he is getting into the corners, etc. Make sure he isn't cutting the entry too tight, and that he is letting the kart "float" on the exit, not chopping it off. Depending on where your son is mentally in terms of driving, watch NASCAR on TV and use it as a way to teach him about how to get around the corner. A lot of times at the track the young ones have a hard time focusing on what you are trying to teach them because they are just having waaay to much fun.

One other thing that may sound stupid but many have overlooked, make sure his seat isn't dragging the ground. Sure makes it hard to gain speed when he is dragging all around the track.

P.S. Make sure you keep it fun for the both of you. Nothing worse than seeing a father/son team fighting all of the time.
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Okay sorry I didn’t at the info in there for this is a rules class every one has to run the 15/66 gear also these are sealed motors you by from the track but I’m running about 9 psi on the right side and about 8 on the left this said guy was running just a few psi more then I was karts definitely not dragging and we did loosen up the nerfs and front bumper and really didn’t see in gain he is getting full throttle and his lines are good actually we were able to get the jump on the other kid and lead 3-4 laps but as soon as the other kid got around he almost lapped us by the 10th lap
 
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flattop1 said:
Sealed ? Exactly what is sealed . Crankcase ? Carb too head ? Valve cover ?
Two engines does kinda rule out the engine .
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My fathers thoughts exactly but yet this guys sounds like it’s turning way harder our first engine only spun to 5080 rpm so we got a new engine that spins to 6k ish but still doesn’t sound like the other kids kart almost make me think I’m going crazy hearing things yes valve cover crankcase and carb are all safety wired with tamper locks
 
Keep in mind your running a kart from the 90's even if you get it 100% your at an disadvantage, are you sure he's running it full out once he gets passed by the others, I've seen with little ones they drive much harder while all clear but once they get passed not so much.
 
I believe you are talking about Callahan, and if David looked at your kart and said its bound up, take his advice there on that point. That i dont believe is the whole issue at 2 seconds off, but its still an issue. The kart numbers need fixing and tires are very important. All these factors together can add up to the slower times.
 
Do you have a max rear tire circumferenc rule? If not .. swell those suckers up as much as possible .. 1/4” equals about 1 tooth on gear, so 1 “ will be equivalent to almost 4 teeth..also looking at your scale numbers, I think that the kart needs more left side weight ( lead on left side of the seat ) and lower cross percentage to about 56-57%
 
flattop1 said:
Tire diameter will affect mph . Bigger tire more mph .
The setup #'s look off with the nose low and the cross a touch high . Lr/Rf.
Toe in or toe out ?
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Although I can’t say exactly what the toe is rig Jt now but I know we had a 1/8 inch toe out sitting on the stand although with these numbers the kart seems to be working well on the handling side
 
Petty Race Engines said:
Do you have a max rear tire circumferenc rule? If not .. swell those suckers up as much as possible .. 1/4” equals about 1 tooth on gear, so 1 “ will be equivalent to almost 4 teeth..also looking at your scale numbers, I think that the kart needs more left side weight ( lead on left side of the seat ) and lower cross percentage to about 56-57%
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No max tire rule I have aired them up as high as 10psi right and 9 psi left but the kart started to get loose coming off 2 and 4 so I dropped them a pound and little man didn’t have to be up on the wheel as much my uncle recommended 56-56-56 but we haven’t been back on the scales to do this also I’m doing poor man scales currently
 
When it slows down does it handle as well or does it get loose the longer he runs ? As mentioned if no tire circumference rule take a good look at your competitions, I bet there a lot bigger, even If there is a rule make sure your at max.
For that era chassis you need to add nose 44.5 %, add left 54.5 %, and lower cross to 55 % then get tires right, I'd contact Earl about tires.

Good Luck !!
 
Dieselmoney92 said:
No max tire rule I have aired them up as high as 10psi right and 9 psi left but the kart started to get loose coming off 2 and 4 so I dropped them a pound and little man didn’t have to be up on the wheel as much my uncle recommended 56-56-56 but we haven’t been back on the scales to do this also I’m doing poor man scales currently
Click to expand...
Don't just air them up more to increase them, STRETCH them then run proper air.
 
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