If your Honda GCV160 is only running with the choke turned on, it is because the carburetor isn’t getting the right amount of fuel for the air, in other words, the engine is running lean, so turning the choke on is limiting the air that goes into the engine.
There are 2 major reasons why the engine might be running lean. Either the carburetor is sucking in more air than it normally does, or it isn’t getting sufficient fuel for the air-fuel mix.
If the fuel isn’t getting supplied in sufficient amounts, it is due to a blocked main jet and can be solved by properly cleaning the carburetor or replacing the carburetor.
On the other hand, if the air is present in excess in the carburetor, it is usually due to the vacuum leak caused by the damaged carburetor gaskets, it can be fixed by replacing the gaskets (with proper installation).
Vacuum leaks due to damaged gaskets or gaskets not being installed properly is the most common cause of Honda GCV160 and the machines using this engine that suffer from the ‘only runs on choke’ issue.
Some people get around this issue by putting a screw through the air filter box that always keeps the choke on. This will lead to more fuel consumption and this isn’t a recommended way of running any engine.
Follow this step-by-step process instead –
To access the carburetor and the gaskets, you’ll need to take out the air filter housing which is attached by 2 bolts that you can access once you remove the cover and the air filter.
Once you have taken out the air filter housing, you’ll be able to access the carburetor and the gaskets.
2. Check All Gaskets
Once you can access the carb, take note of the position of all the gaskets (take a picture if you need to).
Now check to see if any gasket has been worn out. If they are worn out, you should get them replaced.
Make sure to check the orientation of the black plastic heat resistor gasket that is present in between the carburetor and the intake of the engine.
Take note of the circle inside the plastic gasket that is between the intake and carb (as shown in the image). The bottom opening of the circle will face downwards in the engine.
If the gasket is placed such that the bottom part of the circle is facing upwards, it will cause a vacuum leak. It is a very common mistake that people make while reassembly, make sure to check it.
3. Changing The Gaskets
If you find the gaskets to be worn out, it’s best to replace them.
Honda sells a set of carburetor gaskets on Amazon. But it has a few gaskets missing along with air damp.
You can instead get a cheaper clone with all the gaskets and an air filter
While changing the gaskets make sure to arrange them in the proper order. You can watch this video for reference –
If the Gaskets are fine, then it’s likely that your carburetor itself isn’t pumping enough fuel into the combusion chamber. This is usually the case when you’ve left your engine with fuel inside it for a long time.
The fuel without any stabilizer can block the passage inside the carburetor main jet which prevents it from pumping enough fuel into the venturi where the fuel mixes with air.
To fix this issue you’ll need a carb cleaner (and a thin wire might also be helpful). Spray the carb cleaner through all the holes, and clean all the junk that might be settled inside the carb.
You can also follow this video for more detailed instructions –
You also have the option to completely replace the carburetor instead of cleaning it, with either the original part from honda or a cheap clone from Amazon (both works well)
The kit comes with gaskets, fuel filters, a spark plug, and an air filter in addition to the carburetor. All that for less than $20 is a great way to revamp your engine.