7 Steps On How to Adjust Valves on a Portable Generator

Did you know that the optimal performance of a portable generator depends on the level of maintenance given to the generator? The proper adjustments of valves in a portable generator are one of the promising ways of getting stellar performances from your portable generator. This is beside the regular maintenance plan that includes checking and replacing the air filter, changing your generator oil and spark plug. It is good to learn how to adjust valves on a portable generator

If you find your generator is not performing at its best after undertaking other maintenance measures, then it needs valve adjustment. Below is a detailed description of how a valve system works and a simple procedure on how you can adjust the valves of your portable generator.

Under the valve cover, you are going to find;

How to Adjust Valves on a Portable Generator

  • The intake valve:

The intake valve opens to allow the ingoing air and fuel mixture into the cylinder. These valves are adjustable, and you can modify their performance depending on individual engine designs, sizes, and purposes. The valve is made from a soft metal material that you can easily change after it wears off in time through regular use. It is usually located near the carburetor.

  • The Exhaust Valve:

The exhaust valve on your portable generator is a simple yet essential component that needs to be functional for the entire engine system to work efficiently. Its main purpose is to enable gaseous products of combustion out of the cylinder. It opens when the piston passes BDC (Bottom Dead Center) position on its upstroke to allow exhaust gases to flow out of the cylinder. At the same time, the piston is pushed down by the connecting rod and flywheel, as it closes at a point even before reaching TDC (Top Dead Center).

Exhaust valve adjustments may not be necessary very often. Even so, it’s still a good idea if you want to increase the performance or stability of your portable generator.

When to Adjust the Valves of Your Portable Generator

A single underperformance of your portable generator should not necessitate valve adjustments. 

4 main reasons why you should adjust the valves in your portable generator.

If you have observed an irregular running of your generator.

it is advisable to check the valves first before doing anything else. Usually, this problem would be caused by misaligned intake ports and combustion chambers.

if the valve adjustment screws

After some time, if the valve adjustment screws begin to leak fuel oil or air through them, then that means they are not correctly aligned with the ports and chambers, and you need to readjust them after fixing this leakage problem either by using a new piston ring seal or repairing the cylinder head gasket.

Inefficiency In Power Production

If you have been using your generator for a long time, and it doesn’t seem to be producing sufficient power as before. Then maybe it’s time you adjust its valves to get back that lost performance.

Inconsistent Output Failures

If you’re getting consistent output failures on your machine, you should perform valve adjustments to restore it to its optimum performance.

Note: The time interval between each adjustment on portable generators depends on a couple of factors which include;

  • The number of hours used per day of operation.
  • How long your generator has been in use.
  • The type of generator one is using.

Therefore, there is no fixed time interval when you should adjust the valves on your portable generator. There are some instances where different manufacturers recommend when you should do the adjustments.

The Valves Adjustment Procedure

Before you start adjusting the valves on your portable generator, ensure;

  • The generator has cooled down; that is to say, it’s not running, and it’s not hot.
  • If your generator has an electric starter option, ensure the engine switch is in the off position.
  • Drain out all the fuel from the generator’s engine tank. This allows you to have accessibility to the valves without getting any dirty or oily substance on them while doing your valve adjustments.
  • Remove the spark plug cap.

Step#1: Check the valve of your portable generator. The valve is often located at the back of your engine, where it connects with throttle bodies.

Step#2: Proceed to loosen the valve adjusting screws. The valve adjusting screws would be at either side of the cylinder head. These screws need to be loosened and then re-tighten after some time, depending on the brand of your generator, design of the engine, and scale of output generated by it. Note that you should not be doing this step barehanded. You need to put on some protective wear to protect your hands and a screwdriver to tighten and loosen nuts.

Step#3: Readjust the valve adjusting screws at least twice at random intervals after loosening them during your first adjustment, and re-tighten them back later. You need to wait for some time before readjusting a second time or even a third time, depending on what is recommended by the generator manufacturer.

Step#4: After the valve adjustment, you should re-check the air and fuel mixture by retrying the portable generator. You will get to know if there is a significant difference in its operation compared to before doing these adjustments. If, after performing this routine check of your portable generator, it still shows an irregular performance, and it’s not generating enough power. You should do the adjustment procedure all over again. You can adjust the valves on your portable generator more than once if needed. Also, it’s advisable to readjust the valve as often as possible for optimal performance and better fuel efficiency.

The optimum adjustment of portable generators valves will result in;

  • Producing sufficient levels of power output at all times.
  • Optimal fuel efficiency and cleaner engine oil.
  • Less possibility of breakdowns to your generator.

If you’re getting consistent output failures on your machine, you should perform valve adjustments to restore it to its optimum performance. If, for any reason, you think this is not for you, or can’t be done by yourself, then seek professional help from your nearest dealer.

Step#5: You can replace the valve adjusting screws with new ones after readjusting your portable generator valves. This is especially when you realize the existing ones have worn down. Note that if you have determined one of the valves is damaged or is not functioning well, you will be advised by your generator manufacturer on how to replace it.

Step#6: Proceed to replace the spark plug on your generator. Take note that these adjustments would not tune up your portable generator to give you its most outstanding performance as in a new one. However, the adjustments are meant to improve the generator’s working condition by restoring optimal settings of the engine valves and fuel mixture, thus reducing the chances of breakdowns.

It’s also worth noting that your generator manufacturer would advise you on the time scale for how often to check and adjust the valves on your generator. It could be monthly, quarterly, or annually depending on specific recommendations provided by them.

Step#7: After replacing the spark plug cap and cleaning the engine (cylinders), proceed to start your portable generator. Allow the engine to run for a few minutes smoothly at low speed, enabling clearing out any remaining fuel from the engine.

The valve adjustment procedure can take a considerable amount of time to complete. You should also keep in mind that you would need some tools or equipment in hand before starting this routine maintenance work. These include; a spanner or wrench, screwdriver, spare valve adjusting screws, and some protective wear for your hands.

You can perform this routine maintenance yourself, provided you have the necessary equipment and tools needed for valve adjustment. These tools include; spanner, wrench, screwdriver, and protective gear for your hands.

The best way to maintain a portable generator and ensure optimal performance is by doing these routine checks from time to time. This would require you less frequent repairs and as a result get more economical power from your machine.

Common Mistakes to Avoid When Adjusting Valves of Your Portable Generator

how to adjust valves on a portable generatorBelow are some of the common mistakes people make when adjusting their valves on a portable generator.

  • Not reading the instructions carefully.

As earlier stated, it’s essential to read your generator manufacturer’s recommendations on how often and when you need to adjust the valves correctly. Failure to do this could result in problems down the line for your generator, if not immediate.

  • When you over tighten or under-tighten the bolts for adjusting valves.

The adjusting of valves should be done with utmost care and precaution, especially when it comes to over-tightening or under-tightening them. Please ensure that you don’t over tighten or under tighten them since this could damage your generator engine.

  • Screwing in the valve adjusting screws excessively. Ensure that you don’t over screw them into their original seat. Doing so might damage the threads or cause engine failure due to the poor performance of valves.
  • Failure to lubricate the engine after tightening of valves. Before replacing them in their original seat, you should pay careful attention to ensure that all the adjusting bolts are well lubricated. Doing so ensures that the valves are moving smoothly and there is no unnecessary friction between them. Thus ensuring proper movement of engine parts which results in optimal performance.

By ignoring these mistakes, you risk damaging your portable generator, thus causing a loss of its value or even halting operation permanently. Remember that maintaining your generator with periodic checks and adjustments to its valves could be one way of getting it back on track for giving brilliant performances. Secondly, if you don’t want to waste money on repairs or new portable generators, learn how to adjust valves properly.

Tips for Maintaining a Portable Generator Video

Valuable Tips For Maintaining Portable Generators and Prolonging Their Service Life;

  1. Change oil regularly – Make sure you change the oil on schedule, usually every 50 hours or once a year, depending on the type of fuel you use. Frequent oil change helps to remove debris from the unit’s chambers which ensures that it runs smoothly while reducing the risk of engine failure. If you store your gas generator for an extended period, you should change the oil before powering it on.
  2. Check and replace air filter – After changing out the oil in your portable power source, check if there are any clogs in its air filter. It can lead to poor performance, especially when generators are frequently used over long periods, such as during an emergency. Replace them if necessary, and don’t forget to clean its air vents.
  3. Avoid storing fuel for extended periods – It is advisable to use your generator’s fuel within a week after you purchase. Storing fuel for an extended period, especially gasoline, can make it stale, which can hamper the performance of your generator. Stale fuel is one of the significant causes of malfunctioning carburetors.

If you have to store the fuel for long periods, try using gas stabilizers to reduce the risk of staling. It is also recommended that you find a reliable supplier near enough from where you live just in case an emergency happens before your next scheduled visit to their shop!

  1. Clean after each use – Always clean out your generator after each use. This will aid in removing dirt, dust, and other debris that could get caught on the unit’s moving parts, including its valves. If you don’t have time to do a thorough cleaning, then at least wipe down the outside of your portable power source with a damp towel or cloth.
  2. Change spark plug regularly – You should replace spark plugs at regular intervals or when they become worn out. Damaged or worn-out spark plugs can cause poor performance from your portable generator. Worn spark plugs are usually blackened in color and have carbon deposits around their insulators. This can hamper electrical sparks flow through them during operation. While some people prefer to clean them, this is only a temporary solution and could lead to more problems in the future! Replacing worn-out or dirty spark plugs is recommended.
  3. Regularly check your unit’s fuel lines – Make sure your portable generator’s fuel line or a supply line is clear of debris since it could cause clogs in your engine parts. If needed, replace plugs with new ones but never use damaged units that show signs of cracks or breaks. Remember that you wouldn’t want to risk serious damage to your portable power source through careless maintenance, which could ultimately ruin its engine.

Frequently Asked Questions on Valves Adjustments

What are the signs of a worn-out valve?

How to Adjust Valves on a Portable GeneratorA portable generator with a worn-out valve will exhibit the following signs;

  • Leaky gasket.
  • Loss of engine power.
  • Frequent changing of the generator’s spark plugs.
  • Excessive oil consumption and excessive smoke.

When you note these signs, chances are high your portable generator’s valves are worn out, and you should consider replacing them.

What does it mean if a valve is not adjusted for more than 500 hours?

Your generator will still run. However, the parts involved in supplying gas to its engine would become severely damaged, which may cost you hundreds of dollars to have them replaced. And this may turn out to be expensive in the long run.

What is the pinging sound I am experiencing while running my portable generator?

This is because the valve seats are worn out, resulting in rough contact between valves and seats. The rough contact leads to a pinging tone while you’re running the generator. You can easily fix this problem by adjusting the valves of your portable generator, as discussed above.

How do I check if my valves are correctly adjusted?

You can tell if your valves are appropriately adjusted by simply listening to the sounds your generator is making while it runs. If you hear a pinging tone accompanied by spitting gas from carburetors, then your valves are not operating as how they should be. Noticing these signs early on will help you save money since you can adjust or replace the valves right away. If you think that your portable generator’s valves are damaged, it is best to replace them immediately. Otherwise, your generator will surely experience engine failure once damage goes deeper.


Portable generators are great for all kinds of emergencies, and you can use them in a wide variety of instances, including recreational purposes and remote construction. However, the performance of these units is highly dependent on proper maintenance. Besides checking and replacing air filters, oil changes, and spark plug replacements, adjusting the generator’s valves is paramount. In case the valves are worn out, you will need to replace them.

With the procedure above, you can adjust the valves on your portable generator from the comfort of your backyard. However, if you are not sure of what you are doing, contact a qualified generator mechanic from your area. Alternatively, you can contact your generator’s support team. Always check on your generator’s user manual before you undertake any maintenance services.

About Steve Stuart

Steve Stuart is an electrical engineer who developed interest on generators during his school years. After school, he became a generator enthusiast. This is after encountering power supply problems at the area of residence where he lived. Power would be on and off and so food would go bad and the room heater would go off especially during winter. After trying the different generator brands for several years, Steve now provides information on the available brands and products in the market today. Based on his experience, he gives the do’s and the don’ts when it comes to generator use.

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