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  #1  
Old 08-18-2006, 12:58 PM
lucforce lucforce is offline
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Location: Mobile AL
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2 Cylce Performance, Primer-Lack of Power etc.

Due to the some of recent 2 cycle discussions (and posted myths) I felt the need to create this thread. This articular forum is in place for professional cutters. If this is you, then you have come to the right place. If not and you want to learn something, or point out something that I overlooked (this is impromptu), then you are still in the right place. My purpose here is to explain some misunderstandings. Most all of which have been covered on this website, already.

First, the 2 cycle machinery that you are using is air cooled and designed to run at a prescribed rpm under load. This to allow proper air-fuel mixture, proper air flow from the cooling fins, and thus proper engine temperature.

This rpm (and subsequent power output) is determined by: fuel flow, throttle position, carburetion, and LOAD. The first problem that many people create for themselves deals with changing the engine load.

You change the load and thus the performance characteristics when you:
Change the bar length or type (roller tip?) on a saw
Change the line size or type of attachment on a trimmer
Do not run the proper length line (be it from removing or breaking a shield or not) on a trimmer
Add or remove attachments to a blower tube or use damaged tubes
Do not use lube on cutters and do not keep your cutters adjusted on hedge clippers

Given these design constraints, we are asuming optimum conditions.

YOU, the owner of the equipment are responsible for:
Keeping fresh fuel in the machine (not fuel from a can that has been sitting for two months)
Using a quality oil and mixing it properly
Keeping your filters, spark plugs, and fuel lines changed
Rouinely inspecting the equipment for damage or safety issues
Operating the machines as they were designed to be used, and doing so safely

If you do not operate the machine as prescribed you should expect from any quality brand:
Poor performance
Unreliable Equipment
Shortened Machine Lifespan
Higher Repair Costs
Liability Claims against you due to your failure to work in a safe manner or provide safe equipment

ALL 2cycle equipment:
Uses small air filters that need changed regularly
Burns oil in the combustion chamber and so will need the spark plug changed regularly
Uses small fuel lines, that cannot possibly be resilient against the thousands of different fuel varieties and additives in the U.S. AND be resilient against ozone and U.V. while riding around in the back of your truck, which must be replaced periodically. (You want this machine to be inexpensive, correct?)
Burns oil in the combustion chamber and so will need the exhaust cleaned out periodically, but needs this more often if you do not operate it under the prescibed conditions.

Simplified and condensed:
If you run at low rpm you will have incomplete combustion and less power in your machine. This will clog your exhaust and foul your plug, preventing the machine from being able to reach its max rpm. This can also increase the resistance on the secondary side of the ignition coil and lead to premature coil failure.
If you run with old fuel lines, a stopped up air filter, a fouled or improper spark plug and a clogged exhaust, you will have starting difficulty and poor performance.
If you do not keep fresh fuel in you machine, your fuel lines and carburetor parts will deteriorate more quickly, your sparkplug will foul, and your exhaust will clog up more quickly.
If you do not follow the above-you can not rightfully blame the machine or the manufacturer. Very little fails on these machine from design or assembly flaws anymore. The machine fail from a lack of maintenance. Maintenance is something that gets done to prevent and discover problems with the machinery-Not what you do when the machine no longer works.
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Old 08-18-2006, 03:45 PM
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MowerMedic77 MowerMedic77 is offline
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Good post
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Old 08-18-2006, 04:24 PM
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ed2hess ed2hess is online now
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Quote:
Originally Posted by lucforce
Very little fails on these machine from design or assembly flaws anymore. .
I agree with almost everything you said except any carb without a jet adjustment doesn't perform well over a long period of time in the southwest where we operate under extreme temperature conditions. And it very important to be sure that the clutch wear is closely inspected and changed as necessary as well as cleaning the carb and the jet yearly.
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Old 08-18-2006, 05:19 PM
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MowerMedic77 MowerMedic77 is offline
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[QUOTE=ed2hess]I agree with almost everything you said except any carb without a jet adjustment doesn't perform well over a long period of time in the southwest

Almost all of the major engine manufactures are running either a ZAMA or WALBRO carb and both of these manufactures are going to fixed jet carbs with no adjustments this is for the simple fact that this equipment is under strict C.A.R.B(California Air Resources Board) restrictions and they need to run leaner and cleaner in the following years this is the reason for the 4cycle handheld equipment. The days of adjusting your carb richer or leaner to make up for other issues your equipment has will soon be gone.

The part of your statement that sticks out to me is the " doesn't perform well over a long period of time " This means the equipment ran good new but after long hours of use and wear conditions(dirt, bad fuel mix, cylinder wear, old seals, dry fuel lines, ect.) Now the unit is no longer running at its optimum and being unable to make up for other external issues by adjusting the carb has made Fixed jet carbs useless in your opinion.

If the restrictions on this equipment keep going in the direction they are headed you will soon be pushing a broom and sharpening your hand shears for those hedges.

Example: The OPEI(Outdoor Power Equipment Institute) and BAGA(Bay Area Gardeners Asso.) is trying to reverse a ban on gasoline-powered leaf blowers set by the mayor of Palo Alto Calif. the Honorable Judy Kleinberg.
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  #5  
Old 08-18-2006, 09:11 PM
lucforce lucforce is offline
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I do not like the removal of the adjustment screws any less than any other wrench turner.

However-as the medic pointed out, people use carb adjustment to adjust for OTHER issues with their machines. Most of these issues being maintenance related and not due to some mysterious grand Designer.

Back when everything still had adjustable jets, the first thing everyone did was crank on the mixture screw. This happend whether the person knew what he/she was doing or not. Then they would "monkey" around with a dozen other things on the machine before bringing it in to the shop. At least with new CARB standards, this is one more thing to eliminate from the list of things to correct on a machine that a customer worked on first.

I will admit, some machines hae left my hands not running optimally due to the lack of precise carburetor adjustment for the lack of screws. However, I contend that the machines are worn to a point that the carb can not compensate for because of excessive wear due to lack of customer care.

I have worked on equipment in every climate that man can sustain himself longterm. I have not seen an environment that warrented constant tweeking on mixture screws.
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