Hammerhead GTS 150 Twister Go Kart Specs & Review
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One of the few off-road vehicles to receive such a positive response from the North American market is the Hammerhead GTS 150. This Chinese-manufactured go-kart falls out of the stereotype and is known for its practical features and impressive build. Since many agree that it is a dream to ride, it would be interesting to learn more about what the GTS 150 can offer.
Arguably one of the best-selling go-karts in the U.S., the Hammerhead GTS 150 boasts Polaris technology and conquers dunes like nobody’s business. This sporty 4×4 features NASCAR-type seats and safety measures, painted bodywork, and is a charm to ride for casual riders and serious racers.
From its highs and lows to its specs and features, this article will cover the most important details about the Hammerhead GTS 150 – one of the industry’s most capable and value-appropriate four-wheelers. So, stick around and read on.
About Hammerhead GTS 150
The Hammerhead Twister Go Kart (or GTS 150) has been a consistent best-selling go-kart in North America long before Polaris acquired the company. Compared to the competition, the vehicle offers more standard features, including 5-point seatbelts, adjustable bucket seats for both the driver and passenger, an adjustable steering wheel, a digital speedometer, among others. Polaris saw the Hammerhead product line’s ingenuity and decided to include the four-wheeler in its armada of high-quality, affordable vehicles.
Post-acquisition, the Hammerhead GTS lineup was equipped with Polaris-tech components. Aesthetics dramatically improved, with the brush guard changing from a boxy to a drop-nose type. The vehicle’s power mill mates to an external oil cooling system. Additionally, premium Japanese Fuji brand clutches control its stop-and-go function. To top it all off, the absence of manual shifting makes driving this beauty easy to master.
All these standout features are present in the standard Hammerhead GTS 150 and GTS Platinum™ models, with the exception of Platinum trims having racier seats and 5-point seatbelts, and a painted brush guard.
Hammerhead GTS 150 Specs & Features
A four-stroke, air-cooled Honda GY6 engine brings the Hammerhead GTS 150 to life. The stock carb is powerful, with rivets attaching the float bowl to the setup. It can be pretty finicky regarding ethanol content in your fuel. Furthermore, the original carb is difficult to service – you will be better off buying a replacement carburetor (choose the one with bolts attaching the bowl instead of rivets) to resolve any carb issues. The Hammerhead GTS 150 top speed has no advertised figure, but owners claim it to be 50 mph (this may still increase depending on mods).
|Engine Brand Name||Honda GY6 engine|
|Engine Type||4-Stroke, single-cylinder, oil-cooled|
|Carburetion System||Carburetion, 24-mm KF,CB24J x 1|
|Engine Cooling||Air cooling|
|Engine Fuel||Unleaded gasoline w/ rating of at least PON 87 or RON 91, containing < 5% MTBE (Methyl Tertiary Butyl Ether), < 10% ethanol, or < 5% methanol w/ appropriate cosolvents and corrosion inhibitor|
|Fuel Capacity||6.6 – 8.5 L/1.75 – 2.25 US gal|
|Bore x Stroke Ratio||2.26 x 2.28 in|
|Displacement||149 cm³ / 9.09 in³|
|Valve Clearance Cold (Int/Ex)||0.1 mm (0.004 in) / 0.12 mm (0.0047 in)|
|Horsepower||9 – 10 hp/9.1 – 10.1 PS (6.7 – 7.4 kW @ 7,500 RPM)|
|Maximum Torque||17.6 Nm (1.76 kgf-m, 13 ft-lb @ 5,500 RPM)|
|Top Speed||50 mph (80.5 km/h – owner’s claim)|
|Lubrication||Force & splash|
|Engine Oil & Quantity||30 – 35.5 oz (887 – 1,050 ml) of SAE 10W-40 conventional engine oil|
Alternatives: SAE 10W-40 w/ an API grade of SJ+ meeting JASO T903 MA, MB standards, w/out graphite or molybdenum additives
A fully automatic CVT (Constant Variable Transmission) with internal reverse delivers power to the wheels. The final drive is belt and chain-driven – with the chain having 1/4 – 1/2 inch deflection. When traversing diverse terrain, take note of the vehicle’s fording depth limit. It should be less than the ground clearance and never deeper than the vehicle floor. Furthermore, stay away from excessively steep hills or inclines with more than 15° elevation (20 — 25° for recent-year models) to avoid tipping over.
|Clutch||CVT dry clutch and variator|
|Transfer, Transmission Type||Fully automatic w/ reverse|
|Steering||Rack & Pinion|
|Drive System||Chain drive & Belt, rear 2WD|
The Hammerhead GTS 150 has an electronic CDI mated to an electric start system. A triple-phase alternator serves as its charging system, while a YTX9-BS battery like a Banshee YTX9-BS Lithium Ion Motorcycle Battery (view on Amazon) and 12V auxiliary outlet powers up electronic accessories.
|Ignition||CDI (Capacitor Discharge Ignition)|
|Idle Speed||1,700 ± 100 RPM – neutral|
|Spark Plug||NGK CR7HSA, 0.024 – 0.028 in gap|
Torque specs: 12-15 Nm (1.22 – 1.53 kgf-m, 9-11 ft-lb) – new; 23-27 Nm (2.34 – 2.75 kgf-m, 17-20 ft-lb) – used
|Fuse||15 Amp (main)|
|Battery||12V (9 Ah)/10 Hr, YTX9-BS format|
|Battery Dimensions (L x W x H)||6.00 x 3.44 x 4.19 in|
Tires & Brakes
Across all models, the brake system consists of dual hydraulic discs at the front and single ones at the rear. Conversely, rims may either be made of steel or aluminum, depending on the model and trim. Tires at the back of the go-kart are wider, lending to the quad’s superb handling and grip.
|Front Tire||Tubeless, AT19 x 7-8|
|Rear Tire||Tubeless, AT22 x 10-10|
|Tire Air Pressure (F/R)||68.9 kPa (0.70 kgf/cm2, 10 psi)|
|Rim Size, Bolt Pattern (F/R)||8×5.5, 4/137 / 10×8, 4/137|
|Wheel Composition||Steel (Black), Aluminum|
|Tire Tread Limit||3 mm (1/8 in)|
|Front Brake Type||Dual hydraulic discs|
|Rear Brake Type||Hydraulic discs|
The front suspension features dual A-arms, while the rear suspension is a swingarm – both with dual shocks. Base GTS models have slightly shorter A-arms, unlike the GTS Platinum 150™ that has longer A-arms and Nitrogen gas shocks. Front and rear suspension travel are not stated in the service manual. But they are guaranteed to improve if you upgrade your go-kart’s suspension setup to that of the Platinum trim.
|Toe-out||3-6 mm (1/8 to 1/4 in)|
|Wheelbase||1,500 mm (59 in)|
|Ground Clearance||5.3 – 5.8 in|
|Suspension Type (F/R)||Dual A-arms w/ dual shocks; Swingarm w/ dual shocks|
Compared to a 150-cc ATV, the go-kart is massive. While its size requires riders to have a sizeable amount of land to ride it in (unlike some ATVs that can squeeze through tight trails), it does have ample room for taller, heavier riders – up to 6’0″. It comes with a 50-lb capacity rear rack and has a payload limit of 400 lbs.
|Length||2,210 mm (87 in)|
|Width||1,397 mm (55 in)|
|Height||1,397 – 1,422 mm (55 – 56 in)|
|Dry Weight||234 Kg (515 lbs)|
|Bed/Rack Dimensions||813 x 254 x 229 mm (32 x 10 x 9 in)|
|Bed/Rack Capacity||22.7 Kg (50 lbs)|
|Distance, Seat-to-Pedal (Front Edge)||533 – 610 mm (21 – 24 in)|
|Distance, Seat-to-Pedal (Seat Back)||965 – 1,041 mm (38 – 41 in)|
|Vehicle Load Capacity Limit||180 Kg (400 lbs)|
|Maximum Trailer Weight||N/A|
The Hammerhead GTS 150 comes standard with individual race-style seats (adjustable, bucket type) and 5-point harness seatbelts that give the vehicle that NASCAR feel. Other features include a brush guard (or roll cage), all-wheel fenders, projector-style headlights, digital speedometer, aggressive, knobby tires, canopy sun tops, and two-tone paint for all models. Body panels are available in red, blue, orange, camo, white, green, and Steel Black.
Hammerhead GTS 150 Pros and Cons
Go-karts are a less popular option among off-roaders due to the impression that these vehicles cater to youngsters more than serious drivers. But the Hammerhead GTS 150 intends to change that mentality. We will cover the highs and lows of the four-wheeler and how it compares to more-preferred all-terrain vehicles:
- Overall, the GTS 150 has more standard features than its counterparts.
- The adjustable steering wheel can accommodate different rider sizes.
- The all-wheel braking system consists of hydraulic disc brakes – front and rear.
- Since the Polaris acquisition, the go-kart’s box-like body styling has changed to a sleeker, more polished look.
- Bucket seats are spaced comfortably apart, allowing both driver and passenger enough space without having to rub elbows while riding.
- Numerous safety measures are in place, ensuring that passengers are unharmed even after a rough ride outdoors.
- Unlike the base models, the Hammerhead GTS Platinum 150 has a 5-Point NASCAR Safety Harness System, brushed aluminum wheels, unique body-styling with wrap-around side panels, and a painted roll cage.
- Nitrogen gas shocks eliminate the variability of older suspension systems and make for a much more controlled and smoother ride.
- The vehicle is strictly for adults. Operators must be at least age 16 years of age and with a valid driver’s license.
- Passengers under 12 are not allowed.
- Only the driver’s side of the bucket seats is adjustable.
- Customer service and aftersales support are not as reliable as GTS owners had hoped. Only a few dealerships stand out in these areas.
- Some riders find the front shocks insufficient and, instead, go for shocks off of a Yamaha YFZ450 or Yamaha Blaster.
- Hammerhead Twister 150 parts like the coil pack, push-button start, and variator are reportedly easily broken.
Like any other go-kart or ATV, most of the issues found in brand-new Hammerhead GTS 150s stem from the absence of a proper pre-delivery inspection. Conversely, they are expected of pre-owned units and typically cost between $150 and $200 – something that the new owners should be ready for before purchasing the said vehicle.
2016 Product Recall
On November 14, 2016, the manufacturer recalled about 9,000 units of 2009 to 2015 Hammerhead Off-Road vehicles – namely GL 150, GTS 150, and GTS Platinum fun-karts – due to a fuel tank defect, causing it to crack and fuel to leak out and potentially pose a fire hazard for users of the said vehicles. The memorandum instructed affected owners to reach out to their nearest dealers and have the fuel tank replaced. Consequently, some GTS owners opted to get aftermarket fuel tanks like Spectra Fuel Tank F6C (view on Amazon) to address the issue.
Recommended Performance Upgrades
1. Upgrade Displacement
Upgrading your GTS 150 from having a 149-cc to a 196-cc displacement will enable the four-wheeler to transfer more energy and power to the driveshaft and, ultimately, deliver more power to the ground.
2. Change Stock Gear
One of the first things some owners do is change the stock gearing of their wheelers. Simply re-gearing your GTS 150 will make it faster. As a general rule, one tooth down (front) and three teeth up (rear) will make your go-kart quicker, while one tooth up (front) and two to three teeth down (rear) will increase its top-end speed. Ensure not to overdo this, as miscalculating either the front or rear sprockets can overwork the engine and cause stalling or potential engine damage.
3. Increase Carb Size
Going for a larger carb size or simply optimizing it will improve the air-fuel mixture for your go-kart. Many GTS 150 owners opt for a carb that is 2-mm or 4-mm sizes larger. On the other hand, mechanically advanced riders and go-kart racers opt for as high as a 32-mm pumper carb.
4. Forced Induction
Either a supercharger or turbocharger will be a great addition to your Hammerhead GTS 150. Your choice of forced induction system will entirely be up to whether you want to get that extra power from the crankshaft or your vehicle’s exhaust system. Between the two options, most riders opt for turbochargers because they are easier to install. Instead of creating a mount that runs along the crankshaft, you will only need a fuel relay and oil pressurized system to complete your turbocharger setup.
5. Install Lift
Installing a 3-inch lift, removing the pan-hard links, and welding the rear section solid improve overall handling on extreme off-road trails and increases rear travel by four (4) inches. You can add two braces to the rear of your go-kart to support the stock engine mounting frame in place of the pan-hard bars. Do not attempt to equip the vehicle with longer shocks while the pan-hard bars are still in place, as this will cause the engine to hit the fuel tank or the back of the seats long before the shocks reach their bump stops.
6. Remove Unnecessary Weight
The power-to-weight ratio is another aspect that affects a vehicle’s acceleration. Taking off unnecessary weight from your GTS 150 and replacing stock parts with aftermarket ones made of lighter material will help your go-kart go faster. Other than essential items in your quad, you may choose to replace the frame, bucket seats, bumpers, mounts, and accessories with more lightweight material. Customizing some of these parts may be required.
7. Add NOS
Installation of a nitrous or NOS kit increases Oxygen availability in your engine’s combustion chamber. The engine then burns more fuel and generates more power that makes your go-kart faster.
The majority of these tweaks are not as troublesome to perform as they appear and can be done relatively quickly by an experienced mechanic or veteran vehicle owner. However, while making your vehicle faster, these performance upgrades put you at greater risk – especially if they intend to benefit you in racing. Not to mention that these changes add to the stress your go-kart experiences, along with making the vehicle’s overall handling less manageable. As long as you factor in your four-wheeler’s limitations and your skills as a driver, you should be okay with modifications.
Hammerhead GTS 150 Price
The list price for a brand-new Hammerhead Twister 150 would range from $2,999 to $3,299 for the standard models depending on year and trim. For the GTS™ Platinum, pricing would be between $3,499 and $3,999. These values do not include freight, set up, tax, title, license, or any other dealer and extraneous fees. Conversely, secondhand units and online auction listings for the GTS 150 are scarce. If you are looking to purchase a pre-loved go-kart, you will have better chances of spotting one through online forums. Parts availability is no problem – thanks to the vehicle’s GY6 engine that has tons of compatible aftermarket parts.
Polaris Inc. is an American manufacturer world-renowned for pioneering the snowmobile industry and introducing groundbreaking innovations in the ATV/UTV industries. Founded in 1954, the company traces back its humble beginnings to solely creating snowmobiles, eventually venturing into motorcycle and all-terrain vehicle production. In 2015, it acquired HH Investment Limited, the original Shanghai-based maker of the Hammerhead GTS 150 Twister Go Kart. Since then, Polaris has made other acquisitions with the aim to expand its operational footprint and market reach around the world.
Conclusion – Hammerhead GTS 150 Review
All in all, the Hammerhead GTS 150 is a value go-kart that would surely be folly to miss. Preceded by its good reputation, the GTS 150 Twister Go Kart has successfully identified the winning formula to breaking the “Made in China” stigma. It is tough on the outside and performs well on the road. It has a loyal following, huge aftermarket support, and an even more massive dealership network. This exceptional quad was and still is one of the best there is in the market.