GYMMEDS 30 Series Torque Converter for Go-Kart & Mini Bike — 1" Bore, Belt & Sprockets, 2–8 HP Upgrade

GYMMEDS 30 Series torque converter is a bolt-on clutch kit designed for 1" straight crankshafts that upgrades small engines to a smoother, more efficient variable-drive system.

This complete torque converter kit replaces many common centrifugal clutches and specific OEM units (including Manco/Comet part numbers referenced) to give go karts, mini bikes, small tractors and other light-duty vehicles reliable, progressive power transfer. Built from iron and aluminum components, the set ships with driver and driven pulleys, sprockets for #40/#41/420 and #35 chains, a drive belt, mounting plate, cover and full hardware to simplify installation on compatible engines.

Will this torque converter fit my engine?

The GYMMEDS unit fits engines with a 1" straight crankshaft bore and a matching flat key. It is intended for small engines from about 2 HP up to 8 HP, with best results most commonly on 6–6.5 HP setups. Confirm your crankshaft diameter and key orientation before ordering — it does not work with 3/4" bores.

• Driver clutch bore: 1" (with flat key)
• Suitable engine range: 2 HP–8 HP (optimal 6–6.5 HP)
• Not compatible with 3/4" crankshaft bores

How does this torque converter change performance on a go kart or mini bike?

Instead of a single-speed centrifugal clutch, the torque converter provides variable gear ratios through centrifugal drive and driven pulley action, letting the engine stay in a more efficient RPM band during acceleration and load changes. That translates to gentler launches, reduced engine strain, and a broader usable speed range without manual shifting. It’s especially useful where load varies, like towing or uneven terrain.

• Engagement range: approximately 2350 ± 200 RPM
• Driven unit overall diameter: 6" with a 5/8" driven pulley bore
• Reduces stress on the engine and existing centrifugal clutches

What’s included and what additional parts might I need?

The kit includes the main drive and driven pulleys, a drive belt, both 10-tooth (#40/#41/420) and 12-tooth (#35) sprockets, an aluminum mounting plate, a plastic cover, and a full set of mounting hardware—everything required for a straightforward swap on compatible machines. Chains are not included, so you’ll need the correct chain for your sprocket choice, and you should have basic hand tools and a torque wrench for proper installation.

• Included: 1" driver pulley, 5/8" driven pulley, belt, 10T and 12T sprockets
• Included: aluminum mounting plate, plastic cover, full mounting hardware
• Not included: drive chain; basic installation tools recommended

Is the build quality suitable for regular outdoor use?

GYMMEDS manufactures the clutch components from iron and aluminum alloys to balance durability and weight. The materials and design are intended for light vehicle duty—recreational go karts, mini bikes, riding mowers and similar applications—where riders expect reliable, long-term operation when mounted and maintained correctly. Proper alignment, belt tensioning, and periodic inspection will extend service life.

• Construction: iron and aluminum parts for durability and lower weight
• Designed for recreational and light commercial use
• Maintenance: check alignment and belt/sprocket wear regularly

Who is this for: The GYMMEDS 30 Series torque converter is intended for DIY mechanics, small-vehicle hobbyists and light-equipment owners who want to replace a worn centrifugal clutch or add a variable drive to a 1" crankshaft engine (2–8 HP range). It’s a good choice if you run go karts, Coleman-style mini bikes, small ATVs, riding mowers or utility machines and you need smoother acceleration, reduced clutch wear, and a robust bolt-on solution that includes the mounting hardware and sprocket options.