Motorcycle Won’t Run Without Choke? Here’s Why

Motorcycle front part

Your motorcycle is not running unless you start it with a choke, is it? Or worse, you have to keep the choke on the entire time you are riding your motorcycle? Without an open choke, is your bike not starting or not running at all?

The main reason for why your motorcycle is not running without a choke is because of clogged petcock, fuel lines, fuel filters or pilot jets of the carburetor. Cleaning the dirt in these parts should solve the issue. Other possible reasons can be dirt in air filters or air leakages.

If it is only the starting problem, i.e., you need to start the bike with choke but can close it after you have started the motorcycle, then it is not a big concern. Cold weather or the motorcycle sitting idle for a long time can cause starting problems.

However, on the other hand, if you need to keep the choke open for the entire duration of your ride and your motorcycle pretty much dies on you as soon as you close the choke, then we need to seriously look into the problem.

Even if you need to start with a choke frequently, it is better to diagnose the problem so that the issue does not escalate.

Now, let us investigate the reasons for why your motorcycle is not running without the choke in detail.

Reasons Why Motorcycle Won’t Run Without Choke

The 2 main reasons for the bike not running without choke are either because of problems in the air flow or because of the fuel flow.

Reason #1: Problems in Air flow

Although the number of cases with issues in the airflow to the engine are low, it is always better to check them just to be sure. Here, the air-fuel mixture entering the engine is important for the motorcycle to run.

So, if the air entering the engine is not sufficient enough, then we have the problem of our motorcycle dying out on us. The most common situation is the bike starts spluttering and eventually comes to a halt.

For this exact reason, we need to check the air filters and make sure that the filters are clean. If you feel there is too much dirt in the filter and not sufficient air is entering the engine, then it is time clean the filters or better, replace them with a new one.

Reason #2: Problems in Fuel flow

Fuel flow issues are the main cause whenever the bike is not running without the choke open. Again, as mentioned earlier, the air-fuel mixture entering the engine system is very important for the motorcycle to run smoothly. Any deviations or problems in sufficient flow of the fuel to the system, the problems are bound to arise.

Okay, I got the theory. So where do I need to check?

Well, the entire fuel flow system.

The petcock, the fuel lines, the fuel filter and of course, the dreaded carburetor. Specifically, the carburetor since it is the main culprit in most of the cases.

If your motorcycle uses a fuel injection system, then this case wont be applicable for you as there will be no carburetor in your motorcycle.

But if your motorcycle uses carburetor for supply, these parts need to be examined. Any dirt in these parts – petcock, fuel line, fuel filter, pilot jets and the carburetor, will prevent the entry of sufficient fuel into the engine system.

Time to Fix the Problem

First and foremost, make sure it is not an air flow problem. Check your Air Filters first. If it is filled with dirt, not enough air can pass through and the air-fuel mixture is just not right for your motorcycle to run smoothly.

If Air filter turns out to be the issue, then clean up the dirt or if applicable, replace the filter with a new one.

However, most of the times when your motorcycle runs only with the choke open, it is not the air but the fuel flow that is causing the problem.

So, once you are thorough with the air filters, it is time to check the fuel flow passage.

Clean the Carburetor

Clogged pilot jets blocking sufficient fuel flow, dirt in the petcock, clogged fuel lines and dirty fuel filters are all the possible causes that needs to be checked in the carburetor.

Since we need to check each and every possible angle here, you have to take the carburetor out of the system.

If you feel disassembling and reassembling your carburetor is a herculean task, do not stress out. Outsource this task to your mechanic. However, if you are sure on getting your hands dirty, well get down to it then.

Here are some tips for you while you are cleaning the carburetor.

  • Note the make and the model of your carburetor and the motorcycle before disassembling.
  • Keep the appropriate carburetor kit ready with you for a smooth cleaning and reassembling.
  • Nuts and Bolts – organize them properly. The rust on the parts makes them impossible to interchange.
  • Clean them with carburetor solution
  • Air hoses can be handy.
  • Adjust the pilot jets first while reassembling.

Be gentle while cleaning up the pilot jets and the fuel lines. We need to be careful in not scratching or damaging the inner lines. Using a solution to clean is the best way to go about it.

Wrapping up

Lets recap.

  • The main reason why your motorcycle is not running without the choke on is because the engine is not getting the right air-fuel mixture for its intake.
  • For air flow problems, check your air filter. Most likely, it is clogged or there is too much dirt on it.
  • If yes, clean the dirt, or better, replace your air filter with a new one.
  • Another problem causing air flow issue could be an air leakage. Check for the rubber bladder and pipes for any leakages.
  • If it is not the air flow problem, then the fuel is not being supplied sufficiently to the engine. And that’s why, choke needs to be switched on to pump in more fuel.
  • Fuel flow problems can be because of dirt in petcock, fuel line, fuel filter, pilot jets and the carburetor. Any clogging in these parts can deter the fuel flow to the engine.
  • So, remove and disassemble your carburetor and clean the pilot jets, fuel lines, filter and the carb – with a carburetor solution and an air hose.
  • Reassemble the carburetor to your motorcycle. Lo and behold, you don’t need the choke anymore to run your motorcycle.