Gearing question

007

Member
I have a gearing question....most guys at our track are running either an 11/63 or a 12/68. I'm about 100 lbs overweight. Tonight I tried a 12/70 and the kart was junk. I was topping out at about 6580 rpm. My question is...am I going to be way different on gearing being 100 lbs overweight or am I out to lunch and getting myself gear bound?
 

gcashwell

Member
I have a hearing question....most guys at our track are running either an 11/63 or a 12/68. In about 100lbs overweight. Tonight I tried a 12/70 and the kart was junk. I was topping out at about 6580 rpm. My question is...am I going to be way different on gearing being 100lbs overweight or am I out to lunch and getting myself gearbound?
If you are 100 lbs overweight, you are going to be junk no matter what gear you are on.
 

alvin l nunley

Premium User
There's not a huge difference between 11/63 and 12/70 (0.1) so I doubt that's your problem. If you turned the same RPM that is. (6580) the mile-per-hour difference on top is only 0.6 mph. The lower ratio should help on the low end and through the turns, just a guess.
One thing; I can't imagine you being 100 pounds over and ever becoming competitive. Sorry, just a personal observation.
 

gcashwell

Member
Thanks for the support and inspiration!
I’m sorry. I was just being truthful. Maybe they have another class that is more suited to your size. My local track has a class that is for big drivers. It’s very popular and good racing.
 
I have a gearing question....most guys at our track are running either an 11/63 or a 12/68. I'm about 100 lbs overweight. Tonight I tried a 12/70 and the kart was junk. I was topping out at about 6580 rpm. My question is...am I going to be way different on gearing being 100 lbs overweight or am I out to lunch and getting myself gear bound?
You would of been better off staying on an 11 and tried it with a 65 rear, don't even take anything bigger than a 68 along to a race track BUT as mentioned your not going to over come 100 lb disadvantage UNLESS all your competition stinks, best thing you can do is get real good with tires, and your set up better be all but perfect.

Good Luck !!
 
At only 6580 RPM, what motor are we on? For clone, too big of a rear gear with not enough RPM, Animal really not enough RPM, even if a flattie id turn more RPM.
 

OVALTECH1

Premium User
If you were on a big momentum track you would stand a better chance that’s for sure but if your breaking momentum a lot your toast. I feel your pain I run flattys at 345 and I cross at 404 so if I screw up my part its turn lengths not kart lengths. Most everyone in my class is on a 12/65. Most days I’ll run my 11 driver just to help it get up and stay on a 64/65 rear. If the track comes in real nice I may switch to a 12 but highly doubtful. I’ll just drop teeth off the rear. I’ve found the 11 to be beneficial to me in restarts and off corner pull so I generally stay on it. In stock class racing where the rules are set to keep all the engines as close as possible for hp it’s just to hard overcoming 50 plus pounds when we’re basically all on the same engine. Learn tires get your set up nailed and find that groove that helps you maintain the momentum you have and you may just surprise em one race day. I feel your pain tho man I do.
 
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Deadman#73

Member
Off other posts and his pic I would say its safe to assume hes on a flathead.

Find the lowest most comfortable way to get down in the seat and scale that way. Get a larger fairing and tuck your knees in. More rpm on that fatty. Wind er up. That much weight your gonna lose somewhere. Focus more on your corners as that is where you have the advantage.
 
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XXX#40

TRUMP 2020
For flat head you should be 7100-7200, go back to the 11 driver, and start on a 65 on the rear, add teeth until you hit those rpms
 

007

Member
Yes we are running in a stock flathead class. The engine builder has said 6800 rpm is the target as he’s done some stuff with the timing to try to help me on the starts
 
So I just made an observation.... the set of tires I’m running, I’ve got 1.75 inches stagger on the front and 2 inches on the rear. The problem is....my right rear tire is 35.75 inches in circumference....
Don't worry about them being little different if they are, start 11/65 and adjust rear gear accordingly to hit your target rpm.
 

007

Member
Don't worry about them being little different if they are, start 11/65 and adjust rear gear accordingly to hit your target rpm.
I was running 11/68 to get to 6800. So my thinking was that if I could have smaller tires I could go down on rear gear and have a few more options. Will a smaller rear gear (due to smaller tire circumference) help with wind up on restarts and out of the corner or is it going to be so minimal that I wouldn’t notice?
 
I was running 11/68 to get to 6800. So my thinking was that if I could have smaller tires I could go down on rear gear and have a few more options. Will a smaller rear gear (due to smaller tire circumference) help with wind up on restarts and out of the corner or is it going to be so minimal that I wouldn’t notice?
Not what you stated earlier post you stated 11/63 OR 12/68 but went to 12/70 was junk and only turned 6580 rpm, So were saying start 11/65 see what you get and adjust, If you want to test tires with less roll out fine see what it does, still start 11/65 and adjust.
 
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