Extra Maintenance by Using Ethanol Fuel


If ethanol fuel has been stagnating in your fuel system for more than two or three months, an ultrasonic cleaning bath won't always clear that glue-like gunge from the jets and airways. This is particularly true if the carburetor are not stripped and are just dunked in a tank as an assembly.

You often need an old-fashioned approach, and that means going to someone with the knowledge and confidence to go inside the carburetor, stripping out every component and individually cleaning them as well as all the drillings in the carburetor bodies themselves. Sometimes they'll need to use chemicals that could cause damage if used incorrectly.

We know about a person who recently bought a motorcycle that had been stood for a time. He spent a small fortune on replacement ignition components because he'd had the carburetors cleaned in an ultrasonic bath, so he ruled them out as the cause of his continuing running problems.

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Rating: 3.67/5 (3 votes cast)

WD-40 and your Motorcycle Chain


Whether or not WD-40 will keep your chain's O-rings happy or ruin them is one of the most controversial topics in motorcycle maintenance. Supporters say WD-40 is great for cleaning your chain and won't harm a thing. Critics say WD-40 – or more specifically the petroleum distillates in WD-40 – will dry our the O-rings, displace the grease, and ruin your chain.

What's the truth?

To begin, 'WD' stands for Water Displacement, and the '40' stands for the 40th formula to be mixed up. The safety sheet for WD-40 says that it's mostly Stoddard solvent, a petroleum product similar to kerosene. So for all intent and purposes, WD-40 is mostly kerosene. And most motorcycle owner manuals actually recommend using kerosene to wash your chain.

Okay, but WD-40 isn't 100 percent kerosene, and there might still be something in that secret formula that will cause your chain's O-rings to swell up and die. So, to find out just how damaging WD-40 might be we disassembled a motorcycle chain an dropped some O-rings into pure uncut WD-40 and let them stew for a week.

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Rating: 5.00/5 (2 votes cast)

The Honda MSX125 as 180cc Pocket Rocket


The Honda MSX125 is a very popular motorcycle in Thailand, one of our mechanics even bought one for home – work transport. The Honda MSX125 is equipped with the same engine you find in the Honda Wave 125i, and as you probably can imagine that engine is not known for high performance.

For Honda MSX125 owners you can buy a wide range of performance enhancing parts, which offer an even wider range of increased performance. Not so long ago we where contacted by Kitaco Japan, so we asked them what they had for solution to give the Honda MSX125 some extra grunt. The Japanese company responded with a 181cc big bore kit that included everything you need to upgrade the engine. The Kitaco 181cc big bore kit also included a oil cooler, Type 2 performance camshaft and a fueling modifier.

The Kitaco 181cc big bore cylinder is plain aluminum, and really stands out from the engine if fitted like that. We decided to spray-paint the cylinder with in the traditional black color. After we fitted all parts, we realized that the Kitaco 181cc big bore kit needed a much less restricted exhaust pipe. Luckily we where able to obtain a Ixil 615BB Full exhaust system from a local dealer for 4500 THB.

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Rating: 2.50/5 (2 votes cast)

Rebuilding Your Two-Stroke's Top-End


Rebuilding a two-stroke's top-end is a relatively cheap, easy and quick way to give your old two-stroke motorcycle a new lease of life. A worn piston and rings won't form a tight seal in the cylinder, which can scuff the bore and starve your engine of power. Fitting a new piston will protect your engine from expensive damage; if a weakened piston cracks after months of abuse can cause all sorts of strife.

During a top-end rebuild, your motorcycle's most highly stress components will be open to the elements, so ensure you clean your motorcycle thoroughly and completely dry it before taking it apart. Remove the fairing to open up some room so it is easy to get your tools in and then disconnect the fuel line from the carburetor. Remove the fuel tank and now you should have unobstructed access to the top end of the engine.

Remove the coolant if the motorcycle has liquid cooling by the drain bolt and empty the engine and radiators of all coolant. Once all the coolant is out of the radiators disconnect the radiator hoses from the engine and remove the spark plug. Remove the exhaust pipe mounts and remove the exhaust system.

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Idle Problems - Clean The Throttle Body


Does your motorcycle have problems holding a stable idle rpm? A dirty throttle body can be the problem. The throttle body is part of the air-intake system that controls how much air enters the engine to facilitate combustion. It is usually located between the air-box and intake manifold. The main component of the throttle body is the butterfly valve that swings open when you twist the throttle grip on the handlebars.

Back in the day this valve was always linked via a throttle cable. Now, drive-by-wire systems are more common on modern motorcycles and make things a bit more complicated to fix.

So how do we clean the throttle body?

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Rating: 4.00/5 (1 vote cast)

Octane Rating at the Pump


For many motorcyclists, the octane number such as 91 and 95, or 85, 89, 93 and even 98 if you travel outside Thailand, on the gas pump might as well read 'who knows what I need'. And it's a logical assumption that when something costs more, it must be better, right? Not necessarily. The best choice at the pump depends entirely on the specific motorcycle, riding style, and conditions. Incorrect choices can rob riders of performance, damage the engine, and waste money.

Octane is a measure of gasoline's or gasohol's resistance to self-ignite during the compression stroke, before the spark plug fires. In all countries around Thailand the octane measurement is specified in RON (Research Octane Number) which is a different standard then used in the US, some people I spoke to had downloaded US/Canadian owners manuals for there motorcycle and got confusing advised octane levels. In America and Canada the octane ratings are specified with another standard called MON (Motor Octane Number) which is a different method of testing octane levels.

In a gasoline engine, if the cylinder pressure is too great as the piston compresses the air/fuel mixture, the fuel will explode prematurely as the piston is still rising. This is called 'detonation' and it can blow holes in pistons if allowed to continue. To put it simply, the higher the octane number, the more resistant the fuel is to detonation.

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Rating: 4.00/5 (2 votes cast)

Bleeding your Motorcycle Brakes by Using a Medical Syringe


I've been using medical syringes to bleed brakes for about as long as I'm in Thailand, which is just over 15 years and they are absolutely the best tool for the job. But you need to have the right medical syringe.

Normal syringe plungers are rubber and that will swell and break when it comes into contact with brake fluid. A nitrile one, which is usually colored blue and not black, can deal with brake fluid. I combine the syringe with a nitrile tube, which you can also get from pharmacies.

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Rating: 2.50/5 (2 votes cast)

Changing Sprockets and Motorcycle Geometry


Changing the final drive sprockets not only affect acceleration and gear patterns, it'll alter your motorcycle's geometry in a massive way and could need remedying depending on how you ride. Adding a tooth (or two) onto the rear cog is a good, cheap, effective modification for trackdays.

But it will also shorten wheelbase and boost the rear's ride height.

The general rule of thumb works on a 2:1 ratio (adding a tooth is usually 2mm extra ride height and vice versa) though every motorcycle is different with differing linkage ratios. You'll find the motorcycle will steer quicker and squat less on corner exit, but you may also find that rear-end grip is diminished slightly. If you like it, fine, but reducing tide height or even preload could be advisable after a session of testing.

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Aftermarket Screen for the Suzuki V-Strom 650


For the Suzuki V-Strom 650 it has a standard screen that can be adjusted to three differnt positions, but you need to undo four screws, move the screen up or down and screw it back in place. You need a screwdriver and about six minutes of fiddling around, which is not ideal.

On its highest setting one of our friends complained that he get ample protection, but gets a bit buffeting on his forehead at 100km/h. So to try and cure it we've fitted a higher aftermarket screen. The aftermarket screen sits about 75mm higher than the standard Suzuki screen.

Fitting the new aftermarket screen took just over six minutes from start to finish. Unscrew the old one and pop the new one in its place with a few additional spacers. The new aftermarket screen comes with a rubber guard which runs round the outside. It looks far more stylish and purposeful than the standard Suzuki screen.

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Two-Stroke Port Timing


Getting to grips with the smoky mysteries of the two-stroke engine can be the work of a lifetime. Let's try and get some of the basics. A two-stroke engine's combustion chamber receives its charge of fuel and air and evacuates its exhaust gasses via an arrangement of ports; holes in the crankcases, barrels and pistons designed to line up at different points in the combustion cycle to produce the right amount of gas flow at the desired point in the rev range.

Of course the size and shape of these apertures has great bearing on how a two-stroke engine will perform, in the same way port size and shape and valve diameter and lift affect the characteristics of a four-stroke engine. For the purpose of this discussion, however, we will stick to the basics of two-stroke port timing, although their size and shape can easily affect their behavior. And, of course, two-stroke being two-stroke, pretty much everything has an effect on everything else.

With a power stroke every cycle, the two-stroke engine has a lot to get through. From induction to exhaust, it all happens inside two-strokes, that is up and down movements of the piston and one revolution of the crank. For a crankcase-scavenged two-stroke, the process begins with the fresh fuel/air mix being drawn into the crankcase by the vacuum left by the rising piston. The charge is compressed (primary compression) by the descending piston and pushed into the cylinder via the transfer port exposed when the piston is about to begin its ascent and closed before it's completed.

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Rating: 1.00/5 (1 vote cast)
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