Gear ratio for honda 2:1 reduction box
- Thread starter sherman8r
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have you tried this http://www.diygokarts.com/speed-calculator.html
The 2:1 reduction box is the issue when using a standard gearing calculator
KartFab
Active member
Standard yard go kart or a race go kart? I'm assuming you have a 4 stroke industrial engine?
centrifugal clutch carts with stock 5-7 hp engine should go around 25 mph
30 series torque converter karts with 5-7 hp engines should go up to 35 mph
40 series torque converter karts with 8-16 hp engines should go up to 40 mph.
If you increase the RPMS (because gearing will burn up your clutch or mess with the belt upon start if you start to go much beyond these max speeds) through performance parts, you will see a 50% gain in theoretical max speed.
Does a gear reduction box make your ratio increase or decrease? e.g. 1 RPM w/gear reduction box = 2 RPMS out or .5 out?
OzFab
Well-known member
First question, is it just a reduction box or is it also a wet clutch (can you hold the output shaft still while the engine is idling)?
OzFab
Well-known member
Ok, that's a good thing... & a bad thing...
The good:
-no need to worry about an external clutch
-you can over gear it slightly
The bad:
-you can't use an external clutch
-repairing/replacing a worn out clutch can be a nightmare
So, you have a 2:1 redux with a wet clutch & 11" tyres, you should be heading for somewhere around 3:1 gearing, give or take, depending on other factors like engine size...
The good:
-no need to worry about an external clutch
-you can over gear it slightly
The bad:
-you can't use an external clutch
-repairing/replacing a worn out clutch can be a nightmare
So, you have a 2:1 redux with a wet clutch & 11" tyres, you should be heading for somewhere around 3:1 gearing, give or take, depending on other factors like engine size...
OzFab
Well-known member
That depends on what size sprocket will fit the engine output shaft; if you can fit a 15tooth sprocket on the engine, what size do you think you would put on the axle?
OzFab
Well-known member
Yep, that's how it works 
KartFab
Active member
You won't feel stupid when you are riding your go kart. Everyone is here to share and learn. Thanks for asking the question.
tazmannusa
New member
Yep that will get you 3:1 after the 2:1 box . Gives you 6:1 .
With the 420 and 11" tires your going to top out way below 45 mph
That is correct. You can multiply your gear ratio by 2 to get your final ratio
OzFab
Well-known member
Whoa, hang on, I missed that bit
If you're using a 420cc engine, you can safely drop the overall ratio to 5:1, which means using an axle sprocket in the mid to high 30s... but it still won't get you to 45mph...
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