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SunL SLA-135 ATV – Complete Review and Specs

Owning an SLA 135 is not all about spending less, and neither is it for the faint of heart. While Chinese quads are cheaper, you have to be willing to put in extra time and brains as they require more challenging maintenance than regular ATVs. Yes, many YouTube tutorials and forums teach you how to do repairs and mods. However, there is little information about this particular four-wheeler. An additional useful resource is what consumers need – and this article is just the thing.

The SLA 135 is a well-known Chinese youth ATV that became popular with families and off-road enthusiasts. This inexpensive quad performs best at full throttle and is a fun ATV for unending dirt roads and flats.

The SLA 135 is considered one of the most affordable youth ATVs ever made. But as the following of this budget-friendly four-wheeler grew, so did consumers who questioned its value for money. Was the SLA 135 thrown into the Chinese ATV hype thoughtlessly, or was it just one misunderstood mechanically complex machine? Find out the answer, and more, in this article.

SLA 135: An Introduction

A controversial quad during its time, the SLA 135 was one of five 110cc models that SunL Group, Inc. released in the early 2000s. It became popular as an inexpensive alternative to top-dollar mainstream bikes produced by Honda, Yamaha, Polaris, and Kawasaki, to name a few. 

This four-wheeler was mostly operated in field conditions in rural areas and could carry 150-pound riders without much effect on power and performance. Experienced drivers below 16 found it easy to do spins and quick turns with its stock tires. However, its popularity and production was short-lived due to consumer complaints and piled up lawsuits about parts failure and poor quality of the bike, which led to some reported injuries incurred by younger drivers.

Safety Issues – Recalls Youth ATVs

On July 17, 2008, SunL Group, Inc., in cooperation with the U.S. Consumer Product Safety Commission, recalled 144 units of SLA90 Youth ATVs – a different ATV model that targeted children aged 12-15 years old.

Several safety measures were absent from the bike: a lack of front brakes, a manual fuel shut-off, no padding to cover the sharp edges on the handlebar assembly, and no tire pressure gauge. However, not part of the fiasco, similar flaws like not having front brakes were found on the SLA 135 too.

Although there were no reported accidents for the SLA90, the recall happened right on time as the identified defects caused a loss of control of the ATV and could endanger children.

I cannot pinpoint if this incident spurred the series of complaints that the general public had about SunL and its other ATVs. But what is clear is that the firm is no longer active, with the SLA 135’s last year of production in 2013.

Red and Yellow ATVs on Grass

SLA 135 Specs & Features

  • Engine – Power comes from a four-stroke, air-cooled, single-cylinder 107cc Honda cub clone engine. A 28-millimeter carburetor handles the air-fuel mixture with a compression ratio of 9.0:1. Fuel tank capacity is 0.81 gallons/3.08 liters (gas use measures in ounces per hour)
  • Drivetrain – An automatic clutch transmission transfers power. It has a two-wheel drive with a 420 chain.
  • Ignition – An electric CDI start system and auxiliary recoil pull-start mechanical backup gives it power.
  • Tires – The SLA 135 rides on 16×8-7 front and rear tires.
  • Brakes – It uses hydraulic disc rear foot brakes with no front brake.
  • Suspension – The front suspension is fully independent with adjustable springs and dual shocks. The rear suspension consists of a solid rear axle with spring and a single shock absorber. Both suspensions allow 7.9 inches of travel.
  • Exterior – It is composed of a steel frame and plastic body material. It comes equipped with full floorboards, a front bash bar and rear racks, 35-watt headlights, a tail light, and foot and mudguards.
  • Three-Way Catalyst & Pulsed Air Emission Control Systems – This reduces the discharge of harmful gases, including Nitrogen Oxides from the SLA 135’s internal combustion engine, into less-toxic pollutants via a redox reaction.

What to Love about SLA 135

The price is the first thing that comes to mind if you think about the advantages of owning an SLA 135, but that’s not all that this four-wheeler has to offer. Its engine is pretty well-kept, even for second-hand buys. There is a lot of power to it when run and gives superb performance when in full throttle.

Assembled versions have a push-button emergency brake that prevents the rider from rolling down the hill uncontrollably. It fully functions on gasoline with no fuel mixing needed and runs smoothly on 87-grade Octane gasoline. All in all, it is a decent ATV for beginners and little kids.

Known Issues and Remedies

While there are many pros about the SLA 135, this little trooper does not come without disadvantages. Here are some common problems that consumers experience with the quad, plus steps on how to fix each:

  • Cheap plastic. Forums and reviews reveal that the frame develops cracks near the lower swing arm joint, which is not the case for its mainstream competition. To enthusiasts, this is indicative of a weaker type of steel for the bike’s frame. A way to fix this is to replace the SLA 135 plastics altogether by getting a new one from online retailers and parts dealers.
  • Damaged chain. Owners have complained that this happens too casually when the guard squashes against the chain. Other times, the chain pops lose when riding uphill or carrying a load or a weightier driver. First, experienced mechanics take a look at swing arm bushings, tension adjustment, and fixing the motor mount. Should the issue still occur after following all these initial checks, you may need to get a new chain and replace the front sprockets.
  • Stuck throttle cable. Since the SLA 135 is commonly used on rugged trails, it comes as no surprise that its throttle cable would get stuck after a day of mudding. Sticky throttles are also a result of worn-out or ungreased cables, issues with the carburetor or EFI, or bound up cables somewhere in the mechanism. It is best to lubricate the throttle cables with a non-aerosol cable lube (not a WD-40). Or if they are all worn-out, replace them with Mr. Gasket 5657 Steel Braided Throttle Cable Kit (view on Amazon).
  • Rear brake issues. Replacing the entire brake system would be the easier route to go.

Reviving a Sitting SLA 135

Three main components you may need to replace are the battery, starter, and the spark plug. Make sure you connect the battery the right way – doing this the wrong way would blow the main fuse and possibly the regulator.

Once you confirm the battery is set right, check with a test lamp if you have power past the fuse. Then check if you have power past the ignition switch and the start button to the solenoid. Inspect brake or gear lever lockouts too.

Lockouts prevent you from starting if the brake is not on or in neutral, or if the engine goes live at the ignition switch but not at the start button.

At this point, your ATV may successfully start but may not completely turn over. When this happens, you need to pour a teaspoonful of fuel down the air intake and see if the quad runs. If it does but dies shortly after, that is an indicator that you need to clean the carb and jet out.

Also, examine the spark plug if it is wet with gasoline when the engine cranks and the float bowl operates properly. It is not advisable to press and hold the start button down too long as this doesn’t help the engine turn over in any way.

Popping Sounds

Oil leakage or dirty carburetor is a typical cause of this problem. You may need to check the exhaust and see if the pipe came undone from the engine. If yes, put it back in place and tighten it down. Likewise, sort out the sealing ring between the cylinder head and exhaust pipe.

Give it a new spark plug, and use the quad for a while to allow it to settle into running again. If the popping sound continues persists, then start looking into whether the bike needs a gasket/seal for the exhaust or if that part is missing. Likewise, check if there is oil leaking out from the engine.

Man Riding ATV on Brown Path During Daytime

Common Questions

  • What is the top speed of an SLA 135? Its top speed records at 38 mph. Second-hand SLA 135s ride at an average of 22 mph.
  • How much is an SLA 135 ATV? Since the manual for this ATV is quite troublesome to find, we can only speculate that the MSRP for the SLA 135 ranged between $700 and $1000 when first released in the market. Nowadays, used SLAs sell within the $500 range in different trader sites and by previous owners. Auctions make this bad boy almost as good as free, selling it for as low as $25.
  • Where do I find the VIN on the SLA 135 ATV? Look for a 17-digit alphanumeric code mounted to the frame on the bottom left side of your little trooper. You can also check out VIN decoder sites like to determine your Chinese ATV’s exact make and model.
  • Does the SLA 135 have a speed limiter? The response to this is non-definitive due to a lack of an actual manual specifically for the SLA 135. For reference, most Chinese ATVs have a stop for the throttle lever on the handlebars. Some have it located between the carb and inlet manifold. Other manufacturers have a CDI, which limits revs to a minimal number. You usually have to get an “unrestricted” CDI to increase RPM.

About SunL

SunL Group, Inc. is the maker of SunL SLA 135 ATV, established in May 2005 in Texas. This corporate entity distributed motorsport vehicles in the U.S. from 2005 to 2013 to provide its consumers with eco-friendly, safe, and fun products with the latest technology and highest quality. The firm produced scooters, e-bikes, and all-terrain vehicles at a fraction of ATVs’ price from mainstream manufacturers.

Conclusion – SLA-135 ATV

In a nutshell, the SLA 135 is not your average four-wheeler. Compared to its counterparts, it is not up to scratch in terms of durability, versatility, and features. The quad is not rugged enough for woods on trails, jumps, tricks, rough riding, and high speeds.

On the brighter side, it is very budget-friendly with tons of options for aftermarket parts. It is a decent entry-level bike and a perfect training ground for the beginner mechanic. Is this underrated trooper worth all the hassle? You be the judge.