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Description
Naraku 139QMB / GY6 50cc Super Transmission Kit w/ Clutch, Belt, Variator KitNaraku 139QMB GY6 50cc Super Transmission Kit w Clutch, Belt, Variator Kit Restore lost top speed, eliminate off the line bogging, and completely refresh your drivetrain with the Naraku Super Transmission Kit. Engineered specifically for 50cc and 49cc GY6 50 139QMB 4 stroke engines, this all in one CVT tuning package replaces your entire worn factory transmission setup. By matching a high performance variator, precision balanced clutch assembly, heavy
Naraku 139QMB / GY6 50cc Super Transmission Kit w/ Clutch, Belt, Variator Kit
Restore lost top speed, eliminate off-the-line bogging, and completely refresh your drivetrain with the Naraku Super Transmission Kit. Engineered specifically for 50cc and 49cc GY6 50 / 139QMB 4-stroke engines, this all-in-one CVT tuning package replaces your entire worn factory transmission setup. By matching a high-performance variator, precision-balanced clutch assembly, heavy-duty clutch bell, and a calibrated drive belt, Naraku delivers seamless linear shifting, crisp throttle response, and maximum power transfer to the rear wheel.
What's Included in the Box
- Performance Variator & Drive Face: Optimized roller ramp angles maximize belt travel for improved acceleration and high-end speed. Includes a 26-spline drive face.
- Pre-Assembled Clutch & Torque Spring Base: Features durable, high-friction clutch shoes and an anti-slip torque spring base to ensure positive engagement under load.
- Heavy-Duty Clutch Bell: Precision-vented steel clutch drum designed for rapid heat dissipation, preventing thermal glazing and clutch chatter.
- Premium V-Belt: High-tensile drive belt selected for optimal dimensional stability and minimal stretching under high thermal strain.
GY6 50cc engines come in three distinct case lengths. Use the drop-down menu to select the correct kit configuration for your scooter platform:
| Belt Option | Engine Case Profile | Common Vehicle Applications & Notes |
|---|---|---|
| 669mm Kit | Short Case (10" Rear Wheel) | Fits standard short-case GY6 50cc scooters running small 10-inch rear wheels (e.g., ATM50-A1, VIP, and classic city scooters). |
| 729mm Kit | Long Case (12" or 13" Rear Wheel) | Fits standard long-case GY6 50cc scooters running larger 12 or 13-inch wheels. Always verify your case measurement matches a long configuration. |
| 788mm Kit | Extra-Long Case (Fat-Tire / Custom) | Engineered for extended-case variants, most notably found on the Icebear Maddog 50cc and similar Honda Ruckus clone platforms. |
Technical Specifications
- Engine Compatibility: GY6 50cc / 49cc 139QMB / QMB139 4-Stroke
- Roller Weight Size: 16mm x 13mm (6g weights included)
- Variator Outer Diameter: 88mm
- Drive Face: 26 Splines | 13mm Inner Diameter | 113.7mm Outer Diameter
- Clutch Drum: 22 Splines | 11.10mm Inner Diameter
- Sliding Torque Spring Base: 118mm Outer Diameter
- Manufacturer: Naraku (Germany)
Tuning Note: The included 6g roller weights provide an excellent balanced starting point for stock or lightly modified 50cc engines. If you have an 80cc Big Bore Kit installed, experiment with heavier or lighter weights to match your modified torque curve.
Installation Tip: Clean the crankshaft splines carefully before installing new components. Never use an impact gun to tighten the variator or clutch nuts without a holding tool — improper torque can strip crank threads or crush components.
Questions about parts & compatibility? Visit the contact page. - HB SCOOTERS PARTS - Professional Scooter Dealership in Southern California Since 2008
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.7 ★★★★★
Based on 8 reviews
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Product Reviews
★★★★★ 5
Quality and security-oriented wallet
Color: Adventure Brown - Forest Brown
This is a neatly constructed wallet. The material of the leather feels satisfying to carry unlike previous wallets. This wallet consists of many card slots, and allows ease of access between them. The wallet can fit checks, cash and is just a nice layout and style to be able to look through it. Because some of our cards support RFID and NFC technology, bad actors can try to steal our credentials. This wallet has a material to mitigate these occurrences, but like anything in security whether it be physical security controls or the wide scope of cybersecurity, do not rely on it and try to be up-to-date with the trend. I am sure we would all want to be one step above in relation to keeping our credentials secure. Still, it is an excellently built wallet and I highly recommend it.
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Reviewed in the United States on May 7, 2026
★★★★★ 5
Easy to use
Color: Adventure Brown - Forest Brown
Cards load easier and easy to remove them to use. Holds money and cards for easy use. Nice and supple and wears excellently. Good quality leather and card slot are bigger then other wallets I have tried.
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Reviewed in the United States on May 25, 2026
★★★★★ 5
Beautiful Wallet
Color: With NO Logo - Smooth Nappa Black
Well constructed and beautiful wallet. The black Nappa leather I ordered is soft and smooth to the touch and you can tell by the look, feel, and smell that it is high quality. I love that you can order this with both a logo and no logo for a clean look.
The design on this is well thought out.
I'd definitely recommend this wallet to anyone. It is an amazing value and far superior to any other $30 wallet I've ever seen.
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Reviewed in the United States on March 19, 2026
★★★★★ 4
Almost perfect!
Color: With Coin Pocket - Forest Brown
I purchased this wallet primarily for its generous number of conveniently located slots and its coin pocket. If you can't fit everything you want to EDC in this wallet, you need to think about getting a sling bag! Having returned the same model in Grizzily Brown due to a stitching defect and ordered this one in Forest Brown, I can see it is a richer, lighter shade and the finish seems smoother and more refined. Some of my cards were tight in previous wallet slots, but everything fits great in this one. Why the one star off? First, this wallet is about a quarter inch too large in all dimensions, especially thickness. While it doesn't protrude out the top of my back pocket, it is a challenge to close the button on some pants and it is also snug side-to-side, so removal involves some wiggling until pockets stretch and the wallet breaks in. The leather used in its construction is smooth but stiff at first, given that it is about twice as thick as most American or European wallet leather I've owned: think bullhide. The smell is also a little off, definitely natural cowhide but processed with whatever is used to tan leather in India rather than in the United States. Finally, this looks like something that belongs in a pair of jeans or casual pants, NOT pulled out of a suit at a Michelin star restaurant. The stitching, evenness of dye and lines are far from perfect, but what it lacks in looks it more than makes up for in every day function, character, and anticipated durability.
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Reviewed in the United States on January 13, 2026
★★★★★ 5
The Best Wallet
Color: Boulder Black - Napa Smooth Black
This is the second wallet I have purchased from Bull Guard. The first one is identical and I have used it for approximately one year. The first wallet has held up perfectly. I just decided to buy a second one because I am so happy with the first one and I decided to break up my cards into frequently used in the second, new wallet and less frequently used in the first and older wallet. The capacity of the wallet is excellent. It easily holds all my credit cards, drivers license, bills, insurance ID cards, and my global entry card. The material, workmanship, durability, and quality is also excellent. The wallet is all leather and breaks in perfectly. The size is also perfect fitting perfectly in my rear pocket. For the price, this is the best man's wallet I have ever had and I highly recommend it.
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Reviewed in the United States on November 22, 2025