Dirt Bike Fan Page.

Just because we are fans of Dirt Bikes, we also live regular lives, some live to ride, others ride to live, but the most of us are just fans and addicted to what we think of as the greatest sport on the planet. People, places, races, experiences and indelible memories.

On this hub, I hope to combine the social scene and support it with a few technical bits of information. Continually add a little amusement and hopefully share stories. If any reader has anything to add, let me know if its relevant, it goes in! It is purely for the amusement of fellow Huber's who read the content.

It makes little difference if you have mere passive interest or a seasoned professional racer / mechanic, we all need to develop our skills or alternatively pay for a service.

At the Moto-X Expert hub, the input of information may be down to a single individual, but the resource of information is extensive, and the input can grow from consumer requirement or request.

The Authors own background stems back to a childhood passion, long before the days of Schoolboy Scrambling. Whilst in short pants and unable to reach the ground a Triumph Tiger Cub was the initial introduction, shortly followed by a string of European and eventual Japanese mounts. Funded by a paper round, the unfamiliar network of friends became the only education available without paying the repairers. Necessity is the Mother of invention, and where the cash couldn’t go, the inquisitive nature followed, a kid so full of questions that commanded answers was unusual, it wasn’t small talk, it was me learning my skill, and 40 years later I am still learning. As for racing and bike prep, well I went on to race at club level and climbed the ranks, eventually winning National championships for other riders on bikes prepared by me and a title on a bike ridden by me, 2002 National Veteran Champion. Other developments have been with Jet-Ski's with outside help and the initial development of aircraft engines.

Basic theories you should understand with motocross bikes.

Cubic Capacity (cc) its simple by description, and the formula is nothing new, but so many do not know it. π x b² x s x 4000 = cc when converted into available knowledge b²=bore x bore, s = stroke, this will give you the cc of any bike from available data, usually written on the cylinder of modern engines if no in the data specification. So lets presume we have a cc of 125, a small engine, usually single cylinder. How do we want the power delivery? Well 125cc of liquid can be available in numerous shaped containers, a tall slim glass or a short stumpy glass, the contents still equal 125cc. Think of the glass as power delivery, a tall slim glass may be long linear power, taking a little time to reach the top by slimmer delivery, or high top speed but slow in delivery. Alternatively a short squat glass is fast to climb, but over in seconds and more like fast acceleration with a low top end speed. Where is the relevance? How do you want your power, it is still a 125cc so you can’t have both, its rapid acceleration and a low top speed, or high speed and slow to get up to speed. By giving power in an area it is simply taken from elsewhere, but good tuning can tailor the delivery to the riders style.

Power use, or useful power? Once you have the power characteristic, the next consideration has to be efficiency. All motors produce 100% energy, but how much energy is useable? Noise is energy, but not an energy we need, a quiet engine often produces good power, heat is another waste, but some heat works efficiently to improve performance, even vibration is wasted energy. The old classic scene has deafening sounds, these are not as wasteful as we may think, sure they add a certain class to an event, but the whispering bikes are generally better performing, but by reducing air flow or mean gas velocity an engine can be choked and supressed of delivering power. The energy is not the aim here, it is to maximise efficiency, the optimum output with the fewer resistances is a great target. Old school was about increased compression ratio’s with skimmed heads, multiple rings and a massive list of must do’s and add on performance gadgets. Skimmed heads are compression ratio increasing techniques, but think of the resistance the returning engine stroke has to fight against to overcome the resistance, an engine that will not even propel itself below 4000rpm is little use in Motocross.

The third major theory is perhaps the greatest. Have all the power available, but if it will not connect with the ground, it is wasted! Suspension can be as much as 70% importance, I had a conversation once with Greg Albertyn the 3 times world motocross champion, he agreed the game was three quarters suspension. A bucking bike is not propelling forward, so before money is wasted on making engines faster, remember that as long as your engine runs sweet that ‘suspension is king’ and the start of any bike set-up.

Suggest a topic, we will answer or research for you, simple!

Suspension

Godsend or The Devils work?

We have already talked about the seriousness of having ‘dialled in’ suspension, but what are the effects going to be?

Before we get serious and look at a few benefits, we need to indicate the consequences of getting everything a bit wrong!

When everything is a bit soft, and bottoming out, its rather simple to understand, the bike stops absorbing the shock and the body takes over

Suspension habits

Front Suspension.

Too Hard

• · Front washes out in turns
• · Harsh shocks to your wrists
• · Poor steering
• · Head shake at high speed
• · Bouncing on landing

Too Soft

•   Pitching in turns (snatching of the handlebars)
• · Steering difficulties
• · Rear kicking
• · Rear sliding out
• · Difficulty in exiting Berms
• · Harsh shocks on landing

Rear Suspension

Too Hard

• · Kicking up in straight line
• · Shocks to the ankles and wrists upon landings
• · Rear end sliding out on the exit of turns
• · Lack of traction
• · Skittering on small undulations

Too Soft

• · Difficult to turn tightly
• · Sharp jolts through the bike into the rider
• · Bolting on Braking bumps
• · Heavy metallic thuds on landings
• · Poor traction

Whilst these are some common symptoms experienced with incorrect spring tensions, the damping has significant effects on overall action. To understand damping, imaging waving large paddles in the air? OK, a little wind resistance, but now imagine waving the paddles around under water, everything takes more pressure and moves slower in a linear fashion. That’s the effect of damping, perhaps eventually we can look at how damping works, but for now let’s consider the effects of too much or too little damping. If the suspension compresses and rebounds over a series of small equally spaced moguls or bumps in the track, the suspension will collapse to absorb the undulation, with damping on the rebounding action of the suspension, the speed at which the spring extends back to full length is important. Springs are progressive, which means the more they are pressed the greater the resistance is felt, therefore a rear spring will eventually find its maximum compressed state over a bump of a certain size, then return to its extended state, by including rebound damping in the example, the spring needs to return to its comfortable length in time to hit the next bump, if not it may be close to its comfortable compressed state and become almost rigid. Damping speeds are important here as the spring with too much rebound damping will not unwind in time for the next bump on the track, alternatively if it rebounds too quickly, it may pitch the rider or shake him aggressively. Rebound damping is generally controlled by screw adjusters on the shock body, the usual is screw in for slower action or out for faster action.

Too often the thought of Motorcycle riders conjure up the wrong image, so few nasty people survive in the sport or in fact Motorcycling as a whole. The top picture was taken at a floating bar in the Tropics on a recreational day in the Jungle. Adam Duckworth, front left of the photograph has become one of the Worlds leading Motor Sport Photographers, now publishing editor of Moto magazine and prior as Publishing editor for Motor Cycle news, Adam has frequent pictures published in Global editions of leading publications. In the early entry where US magazine Motocross Action Magazine report on the failing of the GP scene, Adam is credited for many of the shots within the expanded feature.

The lower picture was taken in a town near Barcelona, anywhere south of the Andes is good for early season preparation. This was the third time I had visited the region in pre-season preparation, loads of good tracks, and sunshine! In the picture, just myself and Andrew Walch are Englishmen with all others being from Guernsey where the Guernsey Cart and Motorcycle club have a huge following, strange they think themselves as few in numbers, but by percentage of population, they are a high concentration of addicted sportsmen

Owning an old bike is a pretty hip idea right now, the interest in old stuff is as strong as ever with even schoolboy's waiting to join the ranks of twinshock riders. The scene was primarily designed to bridge the gap from Classic to present time stuff. Evolution bikes were lying around and had no great value, the concept of budget racing was a great idea, but as usual, money seems to be the governing issue. All the old Maico's that used to change hands for a fist-full of Dollars now carry a handsome price tag, typically £3,000 for a decent bike, which rather destroys the concept of budget racing. The Maico is the chosen weapon for many, it's fast and pretty reliable and spares are available.

Buried in the back of my late Mothers shed, was my 1981 Yamaha YZ 465 H, left as it was last ridden in 1982, oh apart from the bits that were borrowed by others and not returned! the project which is having parallel exposure from DBR Magazine will share the public resurrection of this former 'Power House' as it gets dragged out and rejuvenated to race for 2012.

OK, the lastest project, to resurrect my 1981 YZ465 after standing unloved in the shed for 30 years. The cyclinder was pretty bad really, paint blistered, bore rusting and so on. Here's the best bit though, its going public and the progress being followed by DBR Magazine

An on-line manual is not the intended direction, the aim is to research selected areas of importance for the page viewers. Suggest an area for research, and the team will prepare a comprehensive report of how-to and where to go reports for you