Tulsa Engine Warehouse » Repair Tips

2 Stroke Engine – Will Not Start

doc — Thu, 29 Oct 2009 19:12:04 +0000

If you have 2 stroke engine that will not start, you may have one or more of the following problems:

Fuel System

Improper starting technique (see previous post)
Stale fuel
Dirty air filter
Dirty fuel filter
Inoperable choke/primer
Water contamination
Flooded with fuel
Broken/cracked fuel hoses
Carburetor requires repair/service

Ignition System

Weak spark
Fouled spark plug
Faulty stop switch
Faulty wiring
Misadjusted armature/coil air gap
Defective coil/armature

Exhaust System

Stopped up exhaust screen
Stopped up exhaust port

Compression

Low top end compression
Low bottom end compression

Timing

Improperly adjusted armature/coil air gap
Damaged flywheel/flywheel key (rare, but possible)

2 Stroke Starting Tips

doc — Thu, 29 Oct 2009 15:45:43 +0000

Even when everything is working properly, 2-stroke engines can be notoriously difficult to start for those that don’t use the proper starting technique.

Here’s some simple “how to” advise:
1.) Make sure there is fresh fuel mix in the tank.
2.) If equipped, prime the carb using the primer bulb.
3.) Make sure the choke is in the “choke” position.
4.) Make sure the “On/Off” switch is in the “On” position.
5.) Open the throttle slightly so the engine will breathe.
6.) Pull the starter rope until the engine “hit’s” at least once.
7.) Disengage the choke.
8.) Start the engine!

Very Important – In order to avoid potentially severe damage, be sure to allow the engine time to warm up before going to full throttle or putting it under a work load!

* repeat the sequence above if necessary.

2-Stroke Troubleshooting Tips

doc — Thu, 29 Oct 2009 14:58:02 +0000

Troubleshooting is nothing more than a systematic process used to test and evaluate the systems and components of an engine in comparison to an expected result. For our purposes, there are two key points to keep under consideration:

When the test results are positive or as expected, you can eliminate the area being tested as cause for concern and move on to the next suspected area.

When the test results are negative or not as expected, you should focus your efforts on the system or components being tested until the actual cause of the problem is located.

Don’t overlook the possibility that there will be more than one problem to be found with a given engine. You may locate and correct one problem, only to find others.

As mentioned elsewhere, one of the great things about a 2-stroke engine is that because everything is so closely interrelated performance wise, when you correct one problem, it often takes care of other problems without any additional work involved.

Establishing A Base

One of the best ways to improve your results when troubleshooting, is to establish a base of known factors from which you can make other decisions. While it is certainly possible to proceed without first doing this, it can make a big difference in the time you spend during the troubleshooting process. You might also be pleasantly surprised to find that many problems simply “disappear” as a result!

Below I’ve listed the things that I have found to be most effective:

Fresh fuel mix
Clean air filter
New spark plug

Listen Carefully…
With 2-stroke engines in particular, the ability to distinguish the different sounds the engine produces can make a huge difference in your troubleshooting! For example:
An engine that sounds “stopped up”, quite often is!

Simply by paying attention to what you hear (or what you don’t hear in this example) will lead you to an almost immediate “cure” for several potential problems caused by exhaust restriction.

Tips for successful troubleshooting:

Here finally, are some tips, learned over the course of many years, (often the hard way) that should help you through the most difficult situations…

Keep it simple! Always check the easier things first, working towards the more complex!
Never assume that a system or component is working properly. Verify it!
Check only one area at a time and don’t move on to something else until you’ve eliminated the system or component as the cause for your problem.
If you become frustrated, take a breather and walk away from the problem for a while. Don’t allow your emotion to control your logic.
When in doubt, refer to the proper repair manual for information and guidance.

Servicing Air Filters

Carl K — Wed, 07 Oct 2009 19:19:39 +0000

You would be amazed at the things seen day by day in the average repair shop. We frequently get machines in with the complaint that “it won’t start” or “runs bad”… pull the air filter and it’s a total disaster. Then there’s always the engine that comes in with major damage due to dirt ingestion, caused from the same problem.

In any case, it’s money thrown away needlessly, not to mention that engine damages caused by dirty air filters aren’t covered by ANY warranty.

Ok, now that I’ve made my point about the need for frequent servicing of air filters, let’s take a look at the “how to” side of things. Servicing an air filter is neither a hard or time consuming task and I’ll try to guide you with some very generic procedures. Once again, let me point out that should the engine manufacturer suggest a different procedure, your best option will be to follow those instructions.

Frequency of Service
In a pinch, I would recommend that the air filter be checked approximately every two to three hours of usage, with service at a minimum of every five hours of use. In dustier conditions you probably should at least check it more often. If it looks dirty after an attempted cleaning, chances are it’s time for a replacement.

Foam Filters
Before you service the filter, first check to see if it is abnormally dirty and to test the condition of the foam material by squeezing it and turning it loose. It should quickly return to it’s normal size and shape. If it doesn’t pass both tests, you may want to replace it rather than service it.

1. After removing the filter, wash it thoroughly using warm soapy water.
(Your favorite brand of dishwashing liquid should work well for this.)

2. After you’ve gotten it clean, the next step is to rinse all the soap out.

3. Squeeze out the excess water and blot dry with a paper towel or old cloth. If it’s hot, you might want to take a break and give it a little time to air dry.

4. Once the filter is clean and dry, apply about a tablespoon or so of clean 30 wt. motor oil, work it into the foam thoroughly, and blot any excess with a paper towel.

Your done!

Be sure to wipe away any dirt or debris from the container that holds the filter before reinstalling it.

Paper Cartridge Filters

First of all, be aware that on some engines, the air flows in from the underside of the filter, so you may need to remove it to see just how dirty it is. A quick glance from the outside may overlook a mess underneath.

Pre-cleaners
Many engines built today will have a thin foam pre-cleaner installed in front of the paper cartridge filter and if serviced frequently, not only it will help protect the engine, it will also extend the life of the paper filter as well. Service procedures for the pre-cleaner are basically the same for the foam filters shown above.

1. Remove the air filter and separate it from the pre cleaner if so equipped.

2. Tap the paper filter on a solid surface in order to shake loose the heavier deposits.

3. If the filter is not too dirty you can use compressed air from the back side of the filter to blow the remaining dirt from the pleats of the paper element.

Yes, that SOUNDS like a lot of time and/or work, but it really doesn’t take more than a few minutes to insure that the engine is properly protected. Since air filters are so important and aren’t very expensive, it’s not a bad idea to keep one on hand as a spare.