Thursday, December 27, 2007

Alloy Wheel Repair - Save Your Wheels Today!

It is a common misconception that alloy wheel repair is almost next to impossible. Most people believe that it can be a complete waste of effort and money. However, alloy's can actually be repaired to a great extent. Alloy wheel repair is in fact a well studied operation.

Alloy wheels can make quite an impact to the overall look of a car. Further, it can make a big difference to the functioning of the car.

Over the years, car manufacturers have taken a cue from the popularity of specialized alloy wheels and have opted to install modified wheels for their stock cars. Alloy's are now a common factor in most cars but along with its growing popularity comes several concerns regarding its maintenance.

Alloy wheel repair

It is a common misconception that alloy wheel repair is almost next to impossible. Most people believe that it can be a complete waste of effort and money. However, alloy wheels can actually be repaired to a great extent. Alloy repair is in fact a well studied operation. Many professional wheel repair companies can undertake the job perfectly.

Common alloy wheel problems

The most significant of damages that can affect an alloy wheel are radial runout, lateral runout and cracks. These damages will not only make the wheel look ugly but it can also greatly affect the car's driving performance. Let's take a closer look!

Radial runout affects the balance of the tire across its diameter. This results in the tire moving up and down with respect to its central axis while rotating. Lateral runout is damage that affects the balance of the tire across its width. Lateral run out is often left undiagnosed as the tire can look true but balance testing will prove otherwise. In the case of lateral run out if there is significant damage it will often be irreparable. Cracks, depending on the location can be repaired but in certain extreme cases it is safer to get a replacement alloywheel than to use one that has undergone alloywheel repair.

Repair for non-forged wheels

Alloy - wheel repair is often recommended for wheels that are non-forged. Forged alloy wheels are tougher and can also be more expensive. Most of the time, forged wheel repair merely consists of having the wheel refinished. Two-piece and three-piece alloy wheels are also more prone to damage as the outer lips of the wheel are commonly made of softer alloy materials.

Alloy wheel repair- the right timing

The best time to plan for alloy wheel repair is during the warmer months. Normally, alloy repair can take anywhere from three to five hours depending on the extent of the damage. If you want to minimize the damage, use high pressure especially when you are using low profile tires. However, it is important to make sure that the wear of the tire is still even.

Save money with alloy-wheel repair

Alloy's are an expensive investment. Fortunately, alloy repair companies offer you the option to get your wheels to look and function as good as new.

By Steven Magill

Tuesday, December 18, 2007

Motorcycle Carburetor Theory

Motorcycle carburetors look very complex, but with a little theory, you can tune your bike for maximum performance. All carburetors work under the basic principle of atmospheric pressure. Atmospheric pressure is a powerful force which exerts pressure on everything. It varies slightly but is generally considered to be 15 pounds per square inch (PSI). This means that atmospheric pressure is pressing on everything at 15 PSI. By varying the atmospheric pressure inside the engine and carburetor, we can change the pressure and make fuel and air flow.

Atmospheric pressure will force high pressure to low pressure. As the piston on a two stroke engine goes up (or goes down on a four stroke engine), a low pressure is formed inside the crankcase (above the piston on a four stroke). This low pressure also causes a low pressure inside the carburetor. Since the pressure is higher outside the engine and carburetor, air will rush inside the carburetor and engine until the pressure is equalized. The moving air going through the carburetor will pick up fuel and mix with the air.

Inside a carburetor is a venturi, fig 1. The venturi is a restriction inside the carburetor that forces air to speed up to get through. A river that suddenly narrows can be used to illustrate what happens inside a carb. The water in the river speeds up as it gets near the narrowed shores and will get faster if the river narrows even more. The same thing happens inside the carburetor. The air that is speeding up will cause atmospheric pressure to drop inside the carburetor. The faster the air moves, the lower the pressure inside the carburetor.


Most motorcycle carburetor circuits are governed by throttle position and not by engine speed.There are five main metering systems inside most motorcycle carburetors. These metering circuits overlap each other and they are:
* pilot circuit
* throttle valve
* needle jet and jet needle
* main jet
* choke circuit

The pilot circuit has two adjustable parts, fig 2. The pilot air screw and pilot jet. The air screw can be located either near the back side of the carburetor or near the front of the carburetor. If the screw is located near the back, it regulates how much air enters the circuit. If the screw is turned in, it reduces the amount of air and richens the mixture. If it is turned out, it opens the passage more and allows more air into the circuit which results in a lean mixture. If the screw is located near the front, it regulated fuel. The mixture will be leaner if it is screwed in and richer if screwed out. If the air screw has to be turned more than 2 turns out for best idling, the next smaller size pilot jet will be needed.

The pilot jet is the part which supplies most of the fuel at low throttle openings. It has a small hole in it which restricts fuel flow though it. Both the pilot air screw and pilot jet affects carburetion from idle to around 1/4 throttle.

The slide valve affects carburetion between 1/8 thru 1/2 throttle. It especially affects it between 1/8 and 1/4 and has a lesser affect up to 1/2. The slides come in various sizes and the size is determined by how much is cutaway from the backside of it, fig 3. The larger the cutaway, the leaner the mixture (since more air is allowed through it) and the smaller the cutaway, the richer the mixture will be. Throttle valves have numbers on them that explains how much the cutaway is. If there is a 3 stamped into the slide, it has a 3.0mm cutaway, while a 1 will have a 1.0mm cutaway (which will be richer than a 3).

The jet needle and needle jet affects carburetion from 1/4 thru 3/4 throttle. The jet needle is a long tapered rod that controls how much fuel can be drawn into the carburetor venturi. The thinner the taper, the richer the mixture. The thicker the taper, the leaner the mixture since the thicker taper will not allow as much fuel into the venturi as a leaner one. The tapers are designed very precisely to give different mixtures at different throttle openings. Jet needles have grooves cut into the top. A clip goes into one of these grooves and holds it from falling or moving from the slide. The clip position can be changed to make an engine run richer or leaner, fig 4. If the engine needs to run leaner, the clip would be moved higher. This will drop the needle farther down into the needle jet and cause less fuel to flow past it. If the clip is lowered, the jet needle is raised and the mixture will be richer.

The needle jet is where the jet needle slides into. Depending on the inside diameter of the needle jet, it will affect the jet needle. The needle jet and jet needle work together to control the fuel flow between the 1/8 thru 3/4 range. Most of the tuning for this range is done to the jet needle, and not the needle jet.

The main jet controls fuel flow from 3/4 thru full throttle, fig 5. Once the throttle is opened far enough, the jet needle is pulled high enough out of the needle jet and the size of the hole in the main jet begins to regulate fuel flow. Main jets have different size holes in them and the bigger the hole, the more fuel that will flow (and the richer the mixture). The higher the number on the mainjet, the more fuel that can flow through it and the richer the mixture.

The choke system is used to start cold engines. Since the fuel in a cold engine is sticking to the cylinder walls due to condensation, the mixture is too lean for the engine to start. The choke system will add fuel to the engine to compensate for the fuel that is stuck to the cylinder walls. Once the engine is warmed up, condensation is not a problem, and the choke is not needed.

The air/fuel mixture must be changes to meet the demands of the needs of the engine. The ideal air/fuel ratio is 14.7 grams of air to 1 gram of fuel. This ideal ratio is only achieved for a very short period while the engine is running. Due to the incomplete vaporization of fuel at slow speeds or the additional fuel required at high speeds, the actual operational air/fuel ratio is usually richer. Figure 6 shows the actual air/fuel ratio for any given throttle opening.

Carburetor Jetting Troubleshooting

Carburetor troubleshooting is simple once the basic principles are known. The first step is to find where the engine is running poorly, fig 7. It must be remembered that carburetor jetting is determined by the throttle position, not engine speed. If the engine is having troubles at low rpm (idle to 1/4 throttle), the pilot system or slide valve is the likely problem. If the engine has problems between 1/4 and 3/4 throttle, the jet needle and needle jet (most likely the jet needle) is likely the problem. If the engine is running poorly at 3/4 to full throttle, the main jet is the likely problem.

While jetting carburetors, place a piece of tape on the throttle housing. Place another piece of tape on the throttle grip and draw a line (while the throttle is at idle) straight across from one piece of tape to the other. When these two lines are lined up, the engine will be idling. Now open the throttle to full throttle and draw another line directly across from it on the throttle housing. At this point, there should be two lines on the throttle housing, and one on the throttle grip. Now find the half-way point between both of the lines on the throttle housing. Make a mark and this will show when the throttle is at half throttle. Divide the spaces up even again until idle, 1/4, 1/2, 3/4, and full throttle positions are known. These lines will be used to quickly find the exact throttle opening while jetting.

Clean the air filter and warm the bike up. Accelerate through the gears until the throttle is at full throttle (a slight uphill is the best place for this). After a few seconds of full throttle running, quickly pull in the clutch and stop the engine (Do not allow the engine to idle or coast to a stop). Remove the spark plug and look at its color. It should be a light tan color. If it's white, the air/fuel mixture is too lean and a bigger main jet will have to be installed. If it's black or dark brown, the air/fuel mixture is too rich and a smaller main jet will have to be installed. While changing jets, change them one size at a time, test run after each change, and look at the plug color after each run.

After the main jet has been set, run the bike at half throttle and check the plug color. If it's white, lower the clip on the jet needle to richen the air/fuel mixture. If it's dark brown or black, raise the clip to lean the air/fuel mixture.

The pilot circuit can be adjusted while the bike is idling and then test run. If the engine is running poorly just off of idle, the pilot jet screw can be turned in or out to change the air-fuel mixture. If the screw is in the back of the carburetor, screwing it out will lean the mixture while screwing it in will richen it. If the adjustment screw is in the front of the carburetor, it will be the opposite. If turning the screw between one and two and a half doesn't have any affect, the pilot jet will have to be replaced with either a larger or smaller one. While adjusting the pilot screw, turn it 1/4 turn at a time and test run the bike between adjustments. Adjust the pilot circuit until the motorcycle runs cleanly off of idle with no hesitations or bogs.

Altitude, Humidy, and Air Temperature

Once the jetting is set and the bike is running good, there are many factors that will change the performane of the engine. Altitude, air temperature, and humidity are big factors that will affect how an engine will run. Air density increases as air gets colder. This means that there are more oxygen molecules in the same space when the air is cold. When the temerature drops, the engine will run leaner and more fule will have to be added to compensate. When the air temerature gets warmer, the engine will run richer and less fuel will be needed. An engine that is jetted at 32š fahrenheight may run poorly when the temperature reaches 90š fahrenheight.

Altitude affects jetting since there are less air molecules as altitude increases. A bike that runs good at sea level will run rich at 10,000 ft due to the thinner air.

Humidy is how much moister is in the air. As humidy increases, jetting will be richer. A bike that runs fins in the mornings dry air may run rich as the day goes on and the humidity increases.

Correction factors are sometimes used to find the correct carburetor settings for changing temperatures and altitudes. The chart in fig 8, shows a typical correction factor chart. To use this chart, jet the carburetor and write down the pilot and main jet sizes. Determine the correct air temperature and follow the chart over to the right until the correct elevation is found. Move straight down from this point until the correct coreection factor is found. Using fig 8 as an example, the air temperature is 95š fahrenheight and the altitude is 3200 ft. The correction factor will be 0.92. To find out the correction main and pilot jets, multiple the correction factor and each jet size. A main jet size of 350 would be multiplied by 0.92 and the new main jet size would be a 322. A pilot jet size of 40 would be multiplied by 0.92 and the pilot jet size would be 36.8.


Tuesday, December 11, 2007

Car Audio Component Speakers - Available In Many Standard Sizes

Since the automobile was created, there have been many inventors looking to improve their cars with their own work. The car-audio systems are just the same in that hobbyists have constructed a dizzying array of systems from car audio component speakers to systems requiring vans to carry.

When planning a new car stereo car audio system, you have to begin with the car stereo. Models can be found featuring CD changers, sophisticated displays, or even just a simple radio. Many systems are designed simply with volume in mind, featuring a high power output rating that also has a very limited frequency range. For a wider frequency range with smoother response, consider higher fidelity systems that make the sound clearer and crisper, albeit without the overpowering bass "thud." If you listen to classical, loudly or not, you probably want a system focused more on fidelity than sheer volume. On the other hand, classic rock demands to be played loud! Your choice in car audio should be in part decided by your musical tastes.

Selecting the right car audio speakers is not rocket science. Most stereo systems have four component speaker outputs, whose output has two measurements, impedance and power. Impedance is measured in ohms, and the power is measured in watts. These specifications can be quite technically complicated, but for the normal user, it is a simple matter to match exactly the impedance of the speakers with the stereo output channel, and that the wattage of the speaker is equal to or greater than the stereo channel. If you do at least that, then you can enjoy your music !

If you aren't satisfied with the sound coming from your car's stereo, and you want a louder, high-fidelity system, you'll need to get a separate amplifier. After you install the amplifier into your existing stereo, it will read the stereo's signal, amplify it, and then output this increased signal to your speakers. It's easy to add car audio component speakers with an amplifier - just be sure to use the output specifications of the amplifier and not the specifications of your stereo!

Lay out of the car needs to be examined after outlining the specifications of the system that one wants. If one doesn't want do do some big modifications then one needs to order speakers of the proper dimensions suitable to the audio car component which are available in many standad sizes - six inch diameter for example. Amplifiers can be placed at a convenient place anywhere so that it can be connected with wires to all the speakers as well as the stereo.

After you have decide on this you would be ready to install your system. The installation varies greatly from car to car but one common thing is to ensure that the car is off and the battery is disconnected at the time of installation. The car and the stereo both have manuals outlining the procedure of installation, and it is finally up to ones determination to install the system.

Innovations in car-audio systems have led to an array of systems from car audio component speakers to systems for vans. The car stereo car audio system starts with car stereo with features CD changers/fancy displays/just a radio and systems may focus on loudness/quality of sound as required. One should ensure that the impedance on the speakers, matches with stereo output channel, to avoid speaker damage. Driving the speakers normally is from an internal amplifier and for louder/high fidelity system from external amplifier of the car stereo. Car layout determines the size of speaker and location. During installation make sure your car is off, and the battery disconnected.

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Wednesday, December 05, 2007

Classic Cars in Cuba

Havana is a potent mixture of the old and the new. Modern office buildings punctuate the skyline alongside deteriorating Eastern European residential towers. Ancient vehicles, some with more rust than paint, share the road with newer, shinier models, while horse-drawn carts mingle with motorcycles. Flea markets display Cuba holiday mementos - wooden models of cars built in the 1950s, which are still seen on Cuban streets.

'Yank tank', 'máquina' 'cacharro' and 'bartavia' are all words used to describe the American classic cars in Cuba. It is the only place where history and circumstance have combined to enable a whole society to preserve these amazing vehicles and turn them into a national treasure.

About 150,000 classic cars existed at the time of the 1959 Cuban Revolution when the U.S. imposed a trade embargo on Cuba. After this, international trade was made very difficult, so the cars that were present at the time have been nurtured and cared for ever since.

Of the 60,000 classic cars in Cuba, about half are from the 50s, another 25 percent from the 40s and a similar number from the 30s. Brands include Chevrolet, Ford, Cadillac, Buick, Plymouth, Chrysler, Dodge, Willy's, Oldsmobile and De Soto - vintage models of all of these can be seen on Cuba's roads today.


As a clash of cultures and ideologies, few experiences compare with that of rounding a corner in the heart of Old Havana with its crumbling baroque buildings and coming face to face with a gleaming 1955 Thunderbird that looks as if it had just been driven off the lot.

Cubans are increasingly aware of the value of classic cars, particularly when visiting Americans become nostalgic about them. They realise that there is business to be made from hiring them out, and it is therefore possible for those on holiday to Cuba to hire out a classic car for the duration of their stay. Although there are more classic cars in the US overall, an American would have to go to Cuba to see a concentration of the cars filling the streets like a snapshot of 50s USA come to life.

Cuba holiday makers feel they have stepped into a time warp to that perhaps more innocent age, when Americans sported prim and proper outfits and drove shiny, sparkly-wheeled cars in brilliant colours with fins and chrome bumpers. The cars made driving feel special. The size of them and the comfort gave a calm feeling for a time when people were able to take their time and enjoy the good things in life.

Care & Attention

While classic cars are still used for daily transportation, often as taxis, they have also become cherished heirlooms handed down from generation to generation within families, in some cases going all the way back to the 30s.

Most owners of classic cars spend hours applying waxes and polishes and basking in the praise and admiration of passers-by. Some even reminisce about a time when their cars were new, and life itself seemed brighter and as inviting as an open highway.

To own one of these vintages defines who you are, how you spend your time and how you wish to be known, and Cubans will go to incredible lengths to keep their classic cars running. 1950's bumpers and tailpipes are recreated and myriad other parts are adapted. Steering wheels carved from wood, hub cabs made from aluminium cans and plastic sheets for windows are common. While such shortcuts would be frowned upon in the United States, classic car lovers admire the Cubans' ingenuity and their ability to keep the cars running.

The Future for Classic Cars in Cuba

Each day these cars get closer to extinction. They are now outnumbered by boxy Russian Ladas, Volga sedans and more recent Eastern European and Japanese imports. But the biggest threats to Cuba's classic cars are the scarcity of parts and lack of original factory literature to maintain them with uniform standards.

Hopefully they will still be preserved for years to come, even if they become increasingly temperamental with all the alterations they go through. If you're thinking of hiring a classic car on your Cuba holiday make sure to make a ceremonial splash of rum on the car's floorboard for good luck!

Emma Lelliott is the general manager of Captivating Cuba, an independent Cuba holiday specialist. With offices in Havana and the UK, Captivating Cuba can offer expert advice on where you should visit on your Cuba holiday. From a vacation in Varadero to a [ ]holiday in Havana, Captivating Cuba can tailor an unforgettable holiday experience for you. Article Source: