Which size sprocket would fit?

[K4narie]

Hey guys, I have a kart with a GX200 engine. The problem is that the original 5.5:1 gear sprocket doesn’t fit because it collides with the frame. For some reason, I decided to go with a sprocket that gives a 4:1 gear ratio. That turned out to be a mistake, because the clutch slips a lot and overheats, and apparently, the minimum safe ratio is 5:1. (Which also doesn’t fit)

The issue is, I can’t fit any larger sprockets. I also don’t have access to welding equipment, and custom fabricating a jack shaft isn’t possible. Mounting the sprocket outside the frame won’t work either, since the engine would then spin in the wrong direction. I’ve attached pictures of both the old and new sprockets.

I would really appreciate some sort of solution if anyone has an idea

 

[Minimichael]

What size pitch is your chain and sprocket teeth? I'm thinking smaller links and teeth could allow the ratio you seek while using less sprocket space.

 

[K4narie]

What size pitch is your chain and sprocket teeth? I'm thinking smaller links and teeth could allow the ratio you seek while using less sprocket space.

I’m running a 16:63 219 chain and sprocket. The 16t on the clutch is the absolute lowest I can go, same for the 63t.

 

[anderkart]

Your racekart frame was designed for use with 2-cycle engines only (2-cycle racekart engines have their output shaft on the right side, 4-cycle on the left), that's why your frames rear cross-bar is so close & in the way of you installing a larger axle sprocket...

It's actually a very common situation with serveral different brands of racekarts. It's such a common problem that Burris designed and sells a 4-cycle motor mount with a built in jackshaft for guys in your exact situation. I used to race karts like yours at serveral different tracks, lots of guys that raced in the 4-cycle classes either built their own jackshafts, or simply bought the Burris setup and bolted it on.

PS:
Before ordering, you'll need to accurately measure your frame-rail diameter and frame rail-spacing (where the motor mount clamps onto your frame) to be ordering the correct Chassis Plate and lower clamps to fit your frame. (unless you already have a compatible Burris brand of motor mount)

You could either contact/ask Burris, or we could help you determine what tooth-count of clutch, Jackshaft gears & axle sprocket to select for the best compromise between having decent acceleration and your expected top speeds.

You'll need a clutch made for #35 pitch chain too.

Here's a pic of one installed and a link to the Burris site: https://www.burrisracing.com/product/jackshaft-assy/

 

[K4narie]

Your racekart frame was designed for use with 2-cycle engines only (2-cycle racekart engines have their output shaft on the right side, 4-cycle on the left), that's why your frames rear cross-bar is so close & in the way of you installing a larger axle sprocket...

It's actually a very common situation with serveral different brands of racekarts. It's such a common problem that Burris designed and sells a 4-cycle motor mount with a built in jackshaft for guys in your exact situation. I used to race karts like yours at serveral different tracks, lots of guys that raced in the 4-cycle classes either built their own jackshafts, or simply bought the Burris setup and bolted it on.

PS:
Before ordering, you'll need to accurately measure your frame-rail diameter and frame rail-spacing (where the motor mount clamps onto your frame) to be ordering the correct Chassis Plate and lower clamps to fit your frame. (unless you already have a compatible Burris brand of motor mount)

You could either contact/ask Burris, or we could help you determine what tooth-count of clutch, Jackshaft gears & axle sprocket to select for the best compromise between having decent acceleration and your expected top speeds.

You'll need a clutch made for #35 pitch chain too.

Here's a pic of one installed and a link to the Burris site: https://www.burrisracing.com/product/jackshaft-assy/


View attachment 157718

Hey thanks for letting me know that this is an option, I’d definitely consider this, the main thing holding me back from this is that I bought the kart for 200 euro and having a motor mount that costs 1.5x the amount of the whole kart seems a bit too much, but from what I can find so far, this is the absolute best option.