I’ve done around 80 laps on a brand new Tony Kart 401. I hit a small curb once, but they’re pretty flat. Just put the kart on scales and one front wheel has 85lbs while the other has 68lbs. The rear are at 108 and 106. I thought maybe the floor wasn’t even, turned the kart around. Same exact result. I weighed it before with another engine ™ and everything was even. Now I’m running a KA100. I could see not having the radiator weight on the left side may throw things off from where they were, but not this much, and not only on the front. The alignment is good. Tire pressures are the same. Tire diameter is the same too. The only thing I can think is that the frame is bent. Is there a way to tell or bend it back easily? I’m guessing just put something under one front wheel and jump up and down on the other?
I have never thought about this until now because I level and line up my scales to ensure they’re coplanar.
Typically a kart with no weight and a KA100 will usually be pretty even in the front and maybe 10 lbs heavier on the right rear, as there is nothing on the left side and the seat offset isn’t usually enough to make all the difference. If the scales aren’t even, (let’s say the right front scale is high) then you will get a higher than normal reading on the right front and left rear, which could yield a result like you got. In that scenario, if you turn the kart around 180 degrees you will still see that same result because you now have the left rear on the high scale, overloading the left rear and right front as before.
That said, if the frame is bend, a chassis table is typically employed. There are variations but the table is flat and rigid with blocks to mount the axle in. Usually one or more long steel bars are use to tweak the frame and get the measure points on plane.
Another thing, I would check the kingpin and spindle on the light side. The good alignment specs suggest they aren’t bent, but I have bent way more kingpins than frames. It is worth checking before you go to the effort of getting the thing on a chassis table.
Couple quick checks:
Agree with everyone on check the kingpins. Have bent them plenty of times with no impact to any other parts.
Sniper the front. Confirm front is setup correctly with same caster, camber, toe on each side. Once those are performed, do a front sweep measurement for each side. The numbers should be within 1-2mm of each other for each side.
To do the front sweep: Set the Sniper ruler vertical at nose of kart and use the Sniper magnet to hold it. I would place mine between the foot peg bracket and steering wheel lower bearing on the best flat spot I could find. Then slowly turn the wheel left and right measuring how high on the ruler each laser hits. If you have a split/difference in caster it will show up here.
The other quick and dirty check is to move the wheel left and right with no one in kart and rock it corner to corner. If you have a gross bend in chassis you will see a difference in how high one side rocks vs other.
I happen to have a very flat shop floor and have set frames on floor with wood support under rear rails or axle and support under middle of nose. Then measure height to top of C on each side. This method is not good enough for chasing a couple mm, due to concrete leveling and wood difference. However, it will tell me if out by quite a bit.
If you have a reputable shop nearby that has a frame table, those are usually $100-150 to throw the kart on and check/straighten.
Going by threads here (and not my own direct experience), it isn’t unheard of for a frame to be imperfect from the factory. And 10lbs isn’t wild, so it could be as simple as that.
Yes they will relax a bit as you work a new chassis. If it really is a new kart please don’t jump on it to straight it out. Go turn another 80 laps then have it tabled. Let the chassis settle in.
Of course as mentioned above check for something bent, but if it isn’t pulling hard one way or the other send it.
Even some uneven tires having a bit of stagger can have an effect on scaling a kart. That’s why higher end forms of racing they scale without tires with machined uprights mounted to the hubs.
did you make sure the PSI was the same in both tires? I have made that mistake before, especially if the kart has sat for a while before being scaled.
I was thinking similar. Even picking up rubber or rocks can throw it off. Without a suspension, these are crazy sensitive. You can set it on the scales without wheels and tires to remove some variables.
Be very carefull using scales to determine if the kart is Bent or not, there is way to many variabels, generally unless you have a very precise and pro scale setup, it will be very hard toget it right.
Things that Can/will throw you off.
-all Four weight not being 100%level
- Slightly front allignment being off.
- If doing it with tyres on, tyrepressur, uneven wear, dirt on the tyres.
- The steeringwheel not being 100% straight.
In a new frame its not unheard of that it will be a bit off after sometime, but i would never straighten a frame using weight scales, and i would never decided if its bend or not without putting it on a table.
One way to isolate the tires and steering is to support the kart at the kingpin and rear axle. This will show how the chassis is from the spindles inwards.
It would not show bent spindles or kingpins probably won’t show a damaged C, but it will show if the support for it is not where it needs to be.
You can rule out tires quickly by swapping the wheels side to side.
To be honest it wouldn’t cross mind to scale it unless the laser were out of whack.