An 18" motorcycle tire traveling at 55 mph rotates 1433 revolutions per minute or 28.88 times per second. This means that as the tire comes into contact with the road, it changes shape nearly 29 times a second. Considering the physics even further, the mind boggles at the thought of weight transfer under heavy braking, or changing contact patches as the bike is leaned over into a corner.
In a nutshell, motorcycle tires are incredible pieces of engineering!
Luckily for the majority of riders, all the engineering has been done and proven. All we have to do is fit the tires and maintain the pressures. But for some older bikes, finding tires can be challenging. The good news is that a few companies have either found a supply in another country or get tires made here in the USA under license.
(For more about older tires, see the article Motorcycle Tires, for Vintage and Classics)
If you are looking for a very rare motorcycle to buy, the Stafford motorcycle show in the UK is the place to be on April 27th when a machine owned by the legendary builder George Brough goes under the hammer.
The motorcycle in question is a 1939 SS100 owned by the designer himself. It was originally fitted with a sidecar and was used just two days after being registered for the first time (May 24th 1939) by George and Motor Cycling journalist Henry Laird who accompanied him in the London to Edinburgh endurance run of 1939.
The Stafford show is one of the year's major events and well worth a visit, and if you'd like to bid on the Brough, you will need around £140,000 to £180,000 ($232,400 to $298,800) to spare, as this is the estimate placed on it by Bonhams the auctioneers. Good luck with the bidding!
If you've ever had a motorcycle seize on you, you'll know what an unpleasant and expensive experience it can be--not to mention painful!
Many of the racing machines up to the late 70s suffered from seizures due to poor carburation, especially on 2-stroke racers. Then along came the simplest and most effective fix I have ever seen: the power jet carb!
Introduced by Mikuni for use on the TZ350 'F' model of 1979, the 38-mm power jets transformed the carburation of these Grand Prix racing 2-strokes and eventually found their way onto many other bikes.
As a race mechanic, I occasionally had to change brake pads just before a track session. Needless to say, the pressure was on to get it right first time, but in a rush, as time was often very limited.
For the classic owner who does mechanical work on his or her bike, a leisurely pace when doing jobs on the bike is more common (and welcome!). As the job of brake pad replacement must be done properly due to the safety issue, there should be no rushing involved.
As many classic owners are preparing their machines for spring and summer use, now is a fitting time to look at brake pad replacement without any pressure.
Talking to Dutchman, Cor Geraets, recently about his 500-cc Suzuki racer, it struck me that many of the developments for street bikes that came about from racing were often as a result of "over tuning." That is to say, both works and private teams typically attempt to modify their machines throughout the racing season. However, increasing the performance of a given engine often reveals a weak area in the original design. If the engine (for example) is based on a street bike, what was perfectly adequate for street riding may not be good enough for the arduous conditions found on a race track.
As an example, during the modification process of one of Cor's bikes (a GT500 Suzuki), increased engine performance had overtaxed the clutch, causing slip. After a few attempts at "fixing" the problem, Cor eventually enlisted the help of a close friend to build a dry clutch assembly. Now that's a home based project with a challenge!
Having got a 2nd and a 3rd at the Nürburgring in 2013 on the Suzuki, it's safe to say that the new dry clutch worked well. We hope to bring an article on this subject in the near future.
One of the easier tasks to do on a motorcycle is to conduct a D.C. (direct current) check. Using a multi-meter set to D.C. volts, the mechanic simply places the two probes of the meter across the battery terminals.
This test is used for two primary checks: residual battery voltage and charge rate when the engine is running. The residual voltage of a battery is an indication of battery condition and level of charge. On a 12 volt battery, the residual voltage should be around 12.5 to 13 volts. Any voltage less than 10 volts indicates a dead cell (a twelve volt battery has six 2 volt cells) and no amount of recharging will bring that cell back to life.
When checking the charge rate, the meter must be set to D.C. volts in the 20 volt range. With the motorcycle running, the mechanic simply reads the voltage increase as the generator feeds the battery; a typical charge rate on a 12 volt battery is around 13 to 14 volts.
Talking with an old friend over the weekend, it came up that he very much wanted to ride/race in the US, ideally on a classic 2-stroke racer. Although many people would love to do this but don't have the experience, this particular friend has extensive experience having raced for 37 years--mainly on 2-strokes.
The friend in question is Chris Barton. Chris started racing on 125s back in 1977 and has competed in everything from clubman races to the British championships and in the TT where he out qualified Joey Dunlop on one occasion!
So if you have a spare bike for the Mid-Ohio races, Chris would be happy to come over and ride for you. He can be contacted through John Glimmerveen at: firstname.lastname@example.org.
More about Chris can be found here:
While conducting some research for a recent article on Burt Munro and his world record setting Indian Scout, I came across some conflicting information regarding the whereabouts of the actual bike. To set the record straight for now, although there is always the possibility that the bike may move again, the original bike is back in New Zealand.
Getting this information was as simple as contacting a few people in New Zealand, chiefly the Te Papa Museum which is the national museum of New Zealand (other web sites and books had suggested the bike was on display there).
After I contacted the museum, I received a detailed reply regarding the whereabouts of the bike and also further information about the movie and Burt Monro himself.
The bottom line here is that when researching anything to do with classic or vintage bikes, it pays to keep researching and not accept the first plausible explanation of something you are interested in. The web is full of great information for researchers; unfortunately, it is also full of misleading information!
For the record, the original bike is on display at the E Hayes Motorworks Collection which is part of the Haynes hardware and engineering business in Dee Street, Invercargill, New Zealand.
There are many world records relating to motorcycles and their riders. But I have to be honest and say that, for me, the world land speed records set by New Zealander Burt Monro are outstanding.
To take a bike from one continent to another is hard enough, but to have modified that same bike from a 55 mph cruiser to a 190 mph record setter is something else.
Monro's exploits in getting from New Zealand to America and setting records is well documented in the famous movie The World's Fastest Indian starring Anthony Hopkins. Although the movie is not 100% historically correct, it is an excellent movie, and if you've not seen it, you should do yourself a favor and get a copy soon.
When a bike with a wet clutch has been stored for some time, the clutch will most likely need to be freed up before riding.
Over time the clutch plates will become stuck together. If the rider starts the bike and tries to put it into gear, he or she will almost certainly find the bike will lurch forward. For the most part, this can be prevented by freeing the plates as follows before the bike is started:
Select first or second gear
Rock the bike backwards and forwards
Pull in the clutch lever
This simple freeing method should be done any time the bike has stood for a few days--just to ensure the clutch is free.
Note: It is good practice to do this on dry plate clutches too.