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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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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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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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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Motorcycles and Oil Leaking


How irritating are oil leaks? Even a small oil leak can be disproportionately annoying. Motorcycles can and will leak oil; it's often what some of them do best. In an ideal world it wouldn't happen but age, wear and tear, overuse, inactivity and abuse often take their collective toll. Some motorcycles leak oil because of inherent design faults, poor quality components or insufficient gasket faces but in general the vast majority of the modern motorcycles available in Thailand don't tend to fall into this category.

If we talking about motorcycles that are famous for leaking oil we often directly refer to British, German and Indian made motorcycles, and for the budget motorcycle most Thai motorcyclists have not much good to say about Chinese motorcycles if it comes to oil leaking... Japanese motorcycles, despite what you might hear and read elsewhere, can and does leak oil...

The good news is that generally the fixes are relatively simple and straightforward. The supply of parts for even older motorcycles is surprisingly good and we found it simple and easy to obtain a seal for every leak we ever identified.

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Work for the Most Advanced Thai Automotive Company


To be honest, I'm not a good mechanic, my dad was, but that was a long time ago. In spite of that I have the creme dela creme of Thai automotive mechanics working for me... and I often make an interpretation of what really happens in our company... The thing is that I've never father engines that were coveted for their enduring success, while that is what we now many produce, enignes that will last a whole racing season..

Our engine building style/technique could be called a triumph of all modification wishful thinking and talent. For all to make this clear we have to go back about 20-years, and keep an open mind.

My dad was a engine engineer who was involved in the design and the development of fastest 50cc motorcycle in his age, not let the engine size foul you, as the speed record was around 225km/h and well within the acceleration of a modern twin cylinder 650cc... but that is all history...

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Spoked Wheels Maintenance


About 45 years ago, manufacturers were making predictions about how much longer the spoked motorcycle wheel would be with us in the face of the advent of the alloy-cast wheel. I think it's fair to say that they all got it wrong... because spoked wheels are still here.

Part of the argument against spoked wheels was that they're high maintenance compared to their alloy-cast wheel equivalent, but sometimes the fact that you can maintain the wheel and not simply throw it away because it's bent is a big advantage – which is why off-road and most adventure motorcycles have spoked wheels.

I've never laced a wheel up myself because I've always known at least one person that would do it for me. But, like wiring a motorcycle, once you've got your head round it, acquired a few tools, and sourced the stuff you need, it's less aggravation than you'd think, which is fairly obvious given that spoked wheels are mass-produced.

From a adventure bike building point of view, the advantage of spoked wheels is that you can lace the rime size to another rim size. Changing the rim size is, however, a little ambitious for a first attempt; the rim needs to be drilled to suit the hub, spoke lengths need to be worked out, and so on. Bearing that in mind, speak to your wheel builder before cutting the hub out of a wheel you want to modify so that they can make a note of the spoke pattern, whether or not the rim is centered on the hub, and anything else they need to know. Then you can paint, polish, or powdercoat your hub to your heart's desire before having it laced to a new rim.

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Is Your Horn Relay-Switched?


If the horns on your motorcycle are like most blasters installed on modern motorcycles now-a-day, changes are that you not impress the average car when you hit the horn button. While the main culprit might be the horn themselves, a contributing factor to poor horn performance is often the simple fact that with some older motorcycles the horns are activated and powered by the horn button instead of being wired through a relay, as is common on most motorcycles you find currently in the dealer showrooms.

The problem is that switches – especially on some older motorcycle models – can be poor conduits for voltage. That's because they typically involve a pair of contact faces that wear against each other every time the switch is activated producing residue and attracting grime that diminishes the contact area and reduce the voltage passing through the switch. It's not at all unusual to discover that a powered switch with 12 volt fed into it only letting 9 or 10 volts through.

That kind of voltage drop is bad and can damage circuits, and it certainly doesn't encourage optimum performance in critical components like horns, lights and ignition systems.

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How many times have you crashed your motorcycle in the last three years?

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