6 Common Honda CRF150R Problems (Explained)

The Honda CRF150R is a popular motocross bike offering a surprising amount of power and performance for an engine of its size.

That said, every machine has flaws. Owners of the Honda CRF150R have experienced reliability issues with their motorcycles based on a handful of common problems.

This article will inform you of what common problems you should expect with the Honda CRF150R, how to recognize their causes, and how to fix or prevent them.

1. Hanging Idle

One of the common problems reported by owners of the Honda CRF150R is hanging idle. A hanging idle is when the engine revs high when you twist the throttle, but when you release your CRF’s throttle, the idle fails to return to its normal speed.

Not only can a hanging idle be annoying while you’re out on the track ripping dirt, but it can also be dangerous, affecting the performance, handling, and predictability of your CRF150R.

“The bike is an 08 CRF150R I got for my boy last year. I purchased it with a hanging idle, thinking the carb needs to be cleaned. NOPE. Starting with idle high enough to start, the bike seems to run well until I blip the throttle. Idle hangs and stays. If I drop the idle while hanging, the bike usually dies and will not start until I raise it again. It acts like this right after I start it and does not get better if the bike is warmed up. The bike runs great otherwise.”

Multiple possible causes can result in a hanging idle on a Honda CRF150R, including:

• Dirt in the Air Intake.
• Broken Intake Tube.
• Vacuum Port Leak.
• Worn or Damaged Throttle Slide Vacuum Plate or Seal.
• Improper Fuel Screw Setting.
• Improper Pilot Jet Setting.

“I have a 2007 Honda crf150rb that has an unsolvable hanging idle. The bike has full FMF exhaust (powerbomb header and a q4 muffler with spark arrestor taken out. You can turn the idle screw-up, and it will sit there and idle great, but as soon as you touch the throttle, the idle will hang very high and won’t come back down unless I tap the kill switch a couple of times.”

You can fix your CRFs hanging idly by inspecting the air intake, intake tube, and vacuum port for dirt or clogs and cleaning as needed.

Check your throttle slide vacuum plate and seal, replacing either if it’s worn or damaged.

Adjust your fuel screw or pilot jet according to your year model CRF150’s owner’s manual spec.

2. Bike Won’t Start

Another common problem that Honda CRF15R owners report facing is that their bike won’t start. In some cases, the bike stalls out while riding. In others, the rider’s CRF150R won’t turn over.

“I am working on a 08 crf150r. It was running fine, slowed to a stop, and at idle, it began to make a metallic sound and just died. You can kick it over; unlike a bent valve or piston damage, it feels smooth. It just has very little compression now. Do these tend to have the cam timing gear bolt back out and maybe slip time?”

“[I just got a] New CRF150R for my son–his first kickstart bike.  I had the JD jet kit put in at the dealership when we bought it.  It starts much better than stock but still can give him a little trouble (and me) when he stalls in the trails.  It will bump start w no issue, but not always a hill around to assist In the woods. Any suggestions to help it start a little easier, more predictably?  Worse when he dumped it, and the bike was laid on its side.”

Various issues can prevent your CRF150R from starting, including a dead battery, a bad spark plug, a dirty or clogged carburetor, and a faulty ignition system.

Moreover, low compression and inadequate valve clearance can also cause your mini-Honda motocross bike to die or not start.

That said, some owners say the bike is just hard to start because it’s a high-revving mini race bike.

“The 150R is a race bike. Expect it to start harder. You must ensure the fuel screw is set right and use the correct technique to start it depending on engine temp. Cold engine, no throttle, choke on. Press the kicker until you feel the compression, then bring it back up and press it through the stroke. Three kicks at most. Hot engine, no throttle, same kick. Use the hot start if the bike is hot or has fallen over.”

To fix or prevent your Honda CRF150R from developing starting problems, check your battery, spark plug, carburetor, ignition system, compression, and valve clearance, adjusting, fixing, or replacing parts as needed.

Use a multimeter, a test light, a compression tester, and a feeler gauge to diagnose the problem.

Maintain your CRF150R regularly, using fresh, clean fuel.

Related: 5 Most Common Honda CRF 250R Problems (Explained)

3. Carburetor Problems; Flooding, Stalling, Backfiring.

Honda CRF 150R riders sometimes report flooding, stalling, or backfiring due to carburetor problems. Your carburetor is the device that mixes your CRF’s air and fuel in the right proportion for its engine to burn effectively. If your carb is dirty, clogged, or poorly adjusted or maintained, it causes a lean or rich air-fuel mix and all kinds of running problems.

“I took my bike [out] the other day, and some parts were super muddy. I would pull the clutch in on some turns, and even if I gave it some gas, it would stall. It was also backfiring sometimes too. I cleaned the air filter and the plug, and it started yesterday on the 4th or 5th kick. I think the backfiring is me (because of the accelerator pump), but I’m not sure about the stalling. If I’m completely stopped, with the clutch in and giving it some gas, it still stalls. I have a hare scramble coming up, and I don’t want to lose because I’m constantly restarting my bike! HELP”

• Flooding is when the carburetor delivers too much fuel to the engine, causing it to run rich and wet the spark plug.
• Stalling is when the engine stops running due to insufficient fuel or air supply from the carburetor.
• Backfiring is when the unburned fuel in the exhaust system ignites and produces a loud bang.

There are several possible reasons for carburetor problems on a Honda CRF 150R, such as wrong adjustment, a too-rich or too-lean mixture, dirt or clogs in the jets or passages, a faulty needle valve or float, or a bad gasket or seal.

Some riders say they prevent these issues from developing by installing after-market carb kits or re-jetting kits, like the one mentioned by the CRF150R owner below:

“The best thing for you to do is to install the white brothers 150r carb kit or the jd jetting jet kit. Both include instructions and will get your carb jetted and running correctly.”

Additionally, you can prevent carb problems by regularly cleaning and adjusting your CRF’s carburetor.

Use a carb cleaner spray and compressed air to remove dirt or clogs from the jets, passages, and needle valves.

Use a screwdriver to set the fuel-air mixture and idle speed according to the manual.

Check for any air leaks, cracks, or damage on the carburetor parts and replace them if needed.

4. Valve’s Go Out of Sync Easily

One of the most common problems Honda CRF150R owners report is that the valves on their bikes need to be in sync sooner. Once your CRF150R’s Alves fall out of adjustment, it can cause loss of power, poor fuel economy, hard starting, rough idle, and engine noise.

“I just bought a 2013 crf150rb expert for my son… does this bike need periodical valve adjustment maintenance as often as the earlier years, like the 2007s and 2008s? Or did Honda fix the constant valve adjustment maintenance with the newer 2012s and up?”

“No matter if it’s newer, you can still expect the same maintenance intervals as any other model year CRF150R/RB. The carburetor got a revised accelerator pump, so that’s a plus over earlier models (no need for o-ring mod) but any ‘improvements’ done on the 2012-on cylinder heads were for gains in performance, not longevity.”

Some of the potential reasons why your Honda CRF150R’s valves g out of sync are:

• Standard wear and tear on the valves and shims.
• Improper Valve adjustment.
• Dirt or carbon buildup.
• Faulty Cam Chain.
• Fault Cam Chain Tensioner.

That said, more than a few CRF150R owners report the issue isn’t actually with the valves but that the valve springs are too low-quality to keep up with their Honda’s valve action.

“The consensus is that the problem is not with the valves but rather with the valve springs not coping with the task. This leads to the valve not contacting the cam and slamming shut instead of a controlled closing with the valve following the cam profile.”

To prevent your CRF150R’s valves from going out of sync, check and adjust the valve clearance regularly.

Inspect your valve springs to be sure they’re keeping up with the load.

Use a feeler gauge and a wrench to measure and set the gap between the valve stem and the rocker’s arm.

Use a degreaser and a brush to clean the valves and the cylinder head.

5. Engine Cams Might Break

One of the problems Honda CRF150R owners may encounter is with their motocross bike’s camshafts breaking. Broken camshafts can damage the components in your CRF’s engine, causing engine failure and the potential for a collision.

CRF150 Owners have discussed this issue extensively in motocross and dirt bike forums.

The common camshaft breakage problem is caused by a defect in the camshaft design on some older CRF150R models.

This indicates that camshaft failure was so common that Honda replaced the camshafts free of charge on affected bikes.

That said, not all models may have been taken in for repairs.

If you’re experiencing camshaft failure on a 2007-or-earlier Honda CRF150R, we suggest you take it to a dealership to run your bike’s VIN.

6. Insufficient Powerband

The Honda CRF150R is a race bike with a lot of peak power but a little low-end power. One of the common complaints CRF150R riders report is that their powerband is uneven, lacking in the low end, and is therefore insufficient powerband. In some cases, this is the result of an issue with the bike, affecting its speed and handling. In others, riders express a negative opinion about aggressive cam tuning.

“My 2008 crf150r has a huge surge of power at around 3/4 throttle, I am a noob to dirt bikes, being this is my first one, so I thought only two strokes had power bands like that. Does anyone know if this is normal? Just seems odd when pinning the throttle; I almost have no control.”

“The CRF150R is a race bike. It was designed specifically to be competitive in youth MX. It’s a small motor that has a lot of peak power. It does not have much low-end power (or low-end torque).”

“This comes from aggressive cams. When it gets on the cam, it goes. It’s a feature, not a bug.”

If you’re here because you feel the CRF150R’s stock tuning doesn’t fit your dirt rack-riding taste, you can upgrade your air intake system or change your gear ratio.

Swapping out your CRf150R’s sprockets to suit your riding style can boost your low-end torque and void your warranty.

If you upgrade your air intake, you may need to upgrade or at least retube the exhaust system to maintain your air: fuel ratio.

If you’re content with your CRF150R’s stock powerband but noticed a dip in low-end performance, here are a few tips:

• Air filter: Clean or replace the air filter to improve the airflow.
• Spark plug: Inspect or replace the spark plug to ensure a strong spark.
• Fuel quality: Use high-octane and fresh fuel to avoid knocking or detonation.
• Carburetor setting: Adjust the fuel-air mixture and idle speed according to the manual.

What Are the Pros and Cons of the Honda CRF150R?

Pros

• 4-Stroke Engine; doesn’t require oil/fuel mix.
• Impressive torque, traction, and power for a bike of its size.
• Lightweight; easy to handle.
• Customizable
• Reliable and durable, pending proper maintenance.

Cons

• Insufficient Powerband
• Cams May Break
• Valves Go Out Of Sync Easily
• Carb Problems; Flooding, Stalling, Backfiring
• Hanging Idle

What Do the Reviews Say?

“The CRF150R’s engine delivers a smooth torque throughout the rev range giving the rider exactly the power they need when needed. It is the perfect bike for junior motocrossers looking to upgrade their ride to match their skills. It’s powerful, well balanced, and maintains Honda’s known reliability.”

“It’s harder to start and restart than a 2-stroke bike, especially in cold or wet conditions. It’s more complicated to maintain than a 2-stroke bike, requiring valve adjustments, carburetor tuning, and frequent oil changes. It’s more prone to overheat in slow or tight trails, as it has a small radiator and fan.”

What’s the Resale Value of the Honda CRF150R?

What Are Some Alternative Models?

Related: 8 Common Honda CRF125F Problems (Explained)

Sources:

2021 Honda CRF150R [Specs, Features, Photos] | wBW (webbikeworld.com)

2018 Honda CRF150R/Expert Buyer’s Guide: Specs, Photos, Price | Cycle World

Used Honda Crf 150R Motorcycles for Sale Near Me – Cycle Trader

Honda CRF150R motorcycles for sale – MotoHunt