B.O.B.L. REGULATION
“BOBL” is an abbreviation for “Battle of Bottom Link.” This is a road race event in which only motorcycles manufactured up to 1964 with bottom link suspension can participate. Our philosophy is to “recreate the golden age of motorsports in the 1960s,” and we hope to convey the joy of road racing to a wide range of people, from beginners to experienced racers. We aim to create an event where participants and viewers can enjoy the atmosphere of the 1960s racing scene.
Held class
Nomal Class 50 (under 60cc/yearly ranking)
・Expert
・Novice
Modified Class 50 (Under 60cc)
Open Class 90 (Under 100cc)
Endurance (Normal class 50 vehicle used)
Article 1 Participating vehicles
1. In principle, participating vehicles are limited to motorcycles with a displacement of 100cc or less with a bottom link suspension system, produced before 1964.
2. The organizer will decide whether or not to participate in the model that has been continuously produced as the same model. Please be sure to ask the secretariat for a decision on acceptance or rejection before entering.
Article 2 Engine
Displacement
It is possible to increase or decrease the displacement by increasing the bore of the engine, but it is a condition to participate in the corresponding class with the changed displacement. Please be sure to ask the secretariat for the judgment of the participating class before entering. Any change from the original number of cylinders is not permitted.
Supplementary provisions
Modifications that significantly change the appearance of the engine are prohibited. The judgment is decided by the authority of the secretariat.
Valve mechanism
Any change from the original structure of the valve mechanism is prohibited.
Valve
1. Prohibition of changing the valve diameter and valve material.
2. Prohibition of changing the rocker arm ratio, material and structure.
Cam
1. Prohibition of machining camshafts. (build-up, base circle, etc.)
2. Prohibition of valve lifter machining.
Cylinder
1. Prohibition of changing the compression ratio by machining the cylinder.
2. Prohibition of changing the material of the cylinder.
Piston
Prohibition of changing the compression ratio by piston processing. (build-up)
Head
Prohibition of changing the compression ratio by machining the combustion chamber.
Ignition method
1. Prohibit use of non-contact type and CDI. (Use normal point)
2. Prohibit significant weight reduction.
Crank
Prohibition of weight addition and stroke change.
Carburetor
1. The use of flat slide carburetors is not permitted.
2. Up to 20mm in diameter.
Transmission
Modified vehicles using T/M such as C50 and C115 will participate in the modified class.
Cooling device
1. According to the mechanism at the time of production of the vehicle. (Prohibition of water cooling for air-cooled vehicles)
2. Installation of an oil cooler is permitted.
Kick starter
Vehicles participating in the standard class (N50) may have their kick starters removed. However, vehicles participating in endurance races must have a kick starter.
＊ Early model HONDA C102 vehicles with a starter motor are an exception as they do not come with a kick starter from the manufacturer.
Clutch
Mechanisms that leak oil to the outside are not permitted for both dry and wet systems. Modifications from the specifications at the time of shipment from the manufacturer are not permitted.
Modified Class 50/Open Class 90 Special Rules
・It is possible to change the ignition method.
・It is also possible to modify the transmission.
Specifications change list × marks indicate that specifications cannot be changed.
Article 3 Frame
1. As a general rule, we do not allow the use of frames that deviate from the original. Please be sure to ask the secretariat for a decision on acceptance or rejection before entering.
2. Remove both the center stand and side stand.
ARTICLE 4 Rear Swingarm Suspension
1. As a general rule, swingarm shapes other than original ones are not permitted.
2. Square cross-section, elliptical cross-section tubes, and tapered types are permitted only if they are of the same material and shape as the original.
3. The use of a separate reservoir rear shock unit is not permitted.
Article 5 Front Forks
1. Limited to bottom links. (Internal dampers and springs can be modified.)
2. Telescopic forks cannot be used.
3. As a general rule, diversion from other car models is impossible.
＊ If anything is unclear, please ask the secretariat for a ruling.
Article 6 Brakes
1. The front and rear drum brakes must be equipped with independent operating systems. The use of disc brakes is prohibited.
2. Rear wheel handle brakes are prohibited.
ARTICLE 7 Handlebars
1. The width of the left and right ends of the handlebar must be at least 300mm. In addition, the cutting angle should be 20 degrees or more on each side.
2. The clearance between the handlebar and the fuel tank must be 30mm or more.
3. Process the grip end so that it is closed.
4. Grips and levers must have a clearance of 20mm or more from fairings.
Article 8 Clutch/Brake Levers
Each lever end of the clutch/brake must be spherical.
Article 9 Footrest Pedals
The ends of footrests and foot pedals must be rounded to a diameter of 20mm or more and a radius of 8mm or more. Or it must be covered with rubber.
Article 10 Rims and Wheels
1. All vehicles must be equipped with spoked wheels front and rear. Cast wheels are prohibited.
2. Minimum rim diameter is 15 inches, maximum is 18 inches. Maximum rim width is WM1 (1.60).
3. Rims other than those listed above are limited to the original size.
4. Rim materials must be aluminum or steel.
Article 11 Tires
Only commercially available on-road bias tires for public roads are permitted. However, the use of grooved racing tires (bias) developed and sold exclusively for classic races is permitted.
ARTICLE 12 Fuel Tank
1. Only steel and aluminum alloy products are permitted.
2. Only in the case of FRP, use is permitted on the premise that the interior is completely filled with explosion-proof material. If the fuel tank has a breather hose, it must be fitted with a one-way valve and connected to a catch tank with a capacity of 250cc or more.
3. For vehicles with rubber plug type tank caps, be sure to take measures to prevent the cap from falling off in the event of a fall.
Article 13 Oil catch tank / Gas catch tank
1. If you are replacing the oil filler cap and installing a breather, an oil catch tank is required.
2. All vehicles must be fitted with an oil catch tank with a capacity larger than the engine displacement.
3. If you are attaching a drain to the catch tank, secure the drain bolt with a wire.
4. The discharge breather hose from the oil catch tank must be installed facing the intake side of the carburetor.
5. For vehicles with standard breathers, we recommend that you do this in advance.(This may be mandatory at some circuits.)
6. If you remove the breather from a vehicle with a standard breather, attach the hose and return it to the oil vat.
7. All vehicles must be fitted with a gasoline catch tank.
ART.14 OIL UNDER TRAY
1. Attach the oil undertray to the bottom of the engine.
2. The oil undertray must have a structure that can hold half the engine oil capacity. Please install a drain plug as a measure against rainy weather.
＊ 2-stroke vehicles do not need to be installed.
Article 15 Wiring
Please be sure to wire the required wiring points as instructed by the secretariat.
1. For places where it is difficult to wire, such as inspection caps, fix them with packing tape, etc.
2. Carburetor float separate models such as C100 and C105 require installation of a float lock screw. Install the wiring bolt.
3. UUse a wire diameter of 0.6 mm or more for the wiring wire.
＊ Be sure to bend the ends of the wiring bolt.
＊ We sell wiring bolt. Please contact the secretariat.
required
1.fuel line
2.Oil lines and drain bolts for oil catch tanks, etc.
3.muffler bolt
4.exhaust flange bolt
5.Axle shaft (front, rear)
6.swing arm pivot
7.oil filler cap
8.Brake torque rod (front, rear)
9.Externally exposed springs (rear brake, exhaust, etc.)
ART.16 Sprocket Guard
1. Install front and rear sprocket guards to prevent entanglement between the rear sprocket and drive chain.
2. If there is no possibility of entanglement between the rear sprocket and drive chain due to the structure of the exhaust pipe, etc., the sprocket guard is unnecessary.
＊ A sprocket guard is not required for vehicles equipped with fairings.
Article 17 Exhaust System
1. Exhaust pipe must be shaped to discharge to the rear of the vehicle. Also, the exhaust pipe must not protrude beyond the vertical line of the rear wheel highest point.
2. Straight pipe is prohibited. And it is obligatory to install an effective silencer. If the volume is extremely loud, the organizer may decide to cancel the race.
3. Exhaust pipe and silencer materials are limited to steel. This is not the case for 2-stroke silencers.
Article 18 Fairings
When installing the fairing, be sure to meet the following conditions.
1. The front wheels must be clearly visible from both sides.
2. The longitudinal length of the fairing must be between 50cm forward of the vertical line on the front axle and the vertical line on the rear axle.
3. The minimum ground clearance of the fairing is 100mm or more.
4. With the rider on, the parts other than the forearms must be visible from above, behind, and from both sides.
5. Any rear facing part of the fairing shall have a rounded leading edge.
6. The number on the front of the fairing must be slanted within 30 degrees.
7. The rear wheels must be visible over a 180 degree circumference behind the perpendicular to the rear wheel.
8. Use of bikini cowl is prohibited.
Article 19 Fenders
1. The front fender must be installed so that it covers the outer circumference of the tire by at least 100 degrees.
2. For vehicles equipped with fairings, the rules for having a front fender do not apply.
Article 20 Things to remove from the vehicle
The following parts must always be removed.
・Lights such as Headlights
・Taillights
・Blinkers, etc.,
・Rearview mirror
・Center stand
・Side stand
・License plate for public roads
・Guards such as bumpers
Article 21 Prohibited parts, etc.
The following are prohibited.
1. The use of superchargers such as turbochargers and superchargers is prohibited.
2. The use of light alloy front and rear axle shafts is prohibited.
3. The use of alcohol fuels such as methanol is prohibited.
Article 22 Hazard prevention
Hazard Prevention
1. Remodeling that endangers both yourself and others is prohibited.
2. Vehicles deemed dangerous by the race officials during the vehicle inspection will be disqualified from running.
＊ If you have any questions, please seek a decision from the secretariat in advance.
Article 23 Changes To Vehicle Rules
These regulations are subject to change with advance notice from the Secretariat.
Article 24 Bib Plate
1. Vehicles must have the applied bib number on the front and both sides.
2. The plate must be essentially an oval in shape (minimum 21cm in length and 25cm in width).
3. Numbers must always use Arabic numerals and must be clear and easy to see.Fluorescent colors are not permitted for both plates and numbers.
Normal Class 50 / black base, white letters
Modified Class 50 / green base, white letters
Open Class 90/red base/white letters
Article 25 Equipment
1. The helmet must be a full-face motorcycle helmet for on-road use.
2. Please use a helmet that is marked SNELL, DOT, CE/ECE, or MFJ. It is prohibited to use helmets that have decorations listed on them at the time of sale.(SHOEI helmets manufactured within 10 years are acceptable / please check with management for details)
3. Helmet remover will be compulsory.
4. Both the top and bottom of the wear must be made of leather.
5. Wearing a spine pad is mandatory.
6. Shoes must be leather boots without laces. (Use boots that are long enough to cover your ankles.)
7. Wear gloves that do not expose your bare skin while riding. If your bare skin is exposed during the race, you will be subject to a black flag.
＊ Racing gloves with guards are recommended.
＊ Helmets that do not have a chin strap cannot be used.
Article 26 Use of Intercoms and in-vehicle Cameras
1. The use of intercoms is prohibited for both sprint and endurance races.
2. In-vehicle cameras are prohibited from being attached to helmets, clothing, etc.(Can be installed on vehicles)
3. In-vehicle cameras can be attached to vehicles. If installed, please have your vehicle inspected with it installed.
Article 27 About race entry
If you are participating in the sprint race, please check the items in Articles 28 to 29 for which you will participate.
Regarding endurance races, please check Articles 30.
important points
・We do not accept entries for just the endurance race. The condition is that someone from the endurance team participates in the sprint race.
・Even for those who are only participating in the endurance race, it is mandatory to register in the morning, sign a pledge, check equipment, and participate in the briefing.
・If you have not completed the registration process and signed the pledge, you will not be able to participate in the race, so please be sure to arrive at the venue on time.
Article 28 Normal Class 50
The Normal Class will have two classes, Expert and Novice.
You can choose the class you want to participate in when you enter.
The maximum number of entries will be determined according to the circuit where the race will be held. Therefore, there will be a limit on the number of people participating in the race. The maximum number of race classes will be two Expert classes and two Novice classes.
In the case of two races per day and two classes each (Expert and Novice), the top and bottom will be divided according to the order of finish in the first race (qualifying). For the second race (main event), a new class will be created for each class with the top and bottom of the qualifying, and the final race will be fought and awarded.
＊ Priority will be given to the class you wish to enter, but if the number of people needs to be adjusted, you may not be able to race in your preferred class.
＊ Participants with racing experience (past or current MFJ competition license holders/international/domestic B and A) will have their class adjusted. Please contact the management office in advance.
Race
・There will be two races per day.
・Classes will be determined based on the number of participants.
・Races will be held with approximately 15-20 cars per class depending on the circuit.
・Depending on the circuit, the number of laps may differ.
Grid
The grid will be determined by a ping pong ball lottery or by a lottery held by the operator in advance.
Race results
The first race will be the qualifying race and the second race will be the final race, and the awards will be given based on the rankings.
How to Start
Expert
Start by pushing the bike.
＊ 2-cycle vehicles will be announced in advance.
Novice
To prevent accidents at the start, we adopt a starting method in which the rider is placed in first gear and both feet are on the ground.
＊ Rocket starts are not permitted. A rocket start is a starting method in which the vehicle starts suddenly with the clutch disengaged or in neutral.
1.Engine start signal
2.Put the gear in 1st gear and put both feet on the ground.
3.Starts with waving of the Japanese flag
Article 29 Modified Class 50 / Open Class 90
This class is a mixed race.
Race
・There are 1 or 2 races per day.
・We plan to divide the classes depending on the number of participants.
・The number of laps in a class may change depending on the circuit being held.
Grid
The grid will be determined by a ping pong ball lottery or by a lottery held by the operator in advance.
Race results
Prizes will be awarded for each class.
・If there is one race per day, the award will be based on the result.
・If there are two races in one day, the overall ranking will be determined by adding up each race. In case of a total tie, the second race ranking will take precedence.
How to start
It’s a clutch start.
Article 31 Endurance Race (E.O.B.L. 2025 will not be held)
1. Endurance racing and E.O.B.L. (Endurance of Bottom Link) race times and race methods vary depending on the year.
2. Vehicles participating in the endurance race will follow the Normal Class 50 regulations.
3. A team of 3 or more riders can participate.
4. The starting method is the Le Mans style. Depending on the weather, there may be a rolling start.
5. The use of intercoms during races is prohibited.
6. Overtaking is prohibited after the checkered flag. Please follow the instructions from the secretariat and line up on pit road in order. We will confirm your ranking. (Depends on race venue)
7. At some race venues, you will be asked to act as a course marshal.
8. When driving on pit road, please be careful of pedestrians and spectators and drive slowly. (Violating teams will be penalized)
9. Depending on the race, handicaps may be established. Please enjoy.
Special rules /Night Endurance Race
・Requires headlight and tail lamp installation.
・Headlights must be at least 15W and at least 10cm in diameter. Tail lamps must be at least 5W and at least 2cm in diameter.
・The lights will come on during the race, so a light switch must be installed.
＊ LED bulbs cannot be used.
＊ Use the lighting method used by the manufacturer.Lighting only with batteries is prohibited.
＊ If the light is insufficient or difficult to see, you may be subject to a black flag.
Gasoline refueling
・ Each team must prepare a 5L or larger gasoline can.
・ Please include your bib number so we can identify which can your team is carrying.
・ Please have one canister per team available at the gas station.
Race (Usually)
・Before the start of an endurance race, the gasoline in the tanks of participating vehicles will be emptied and a vehicle inspection will be conducted.
・ Using the tank provided at the gas station, fill up with 500ml from your team’s gasoline can and line up your vehicle in the designated grid.
・ During the race, you can refuel 500ml per pit stop.
・When refueling, be sure to stop the engine before refueling.
・You can change riders when refueling.
・Riders are not allowed to refuel themselves after a ride. Be sure to have at least two people perform refueling work.
・Gas stations will close 15 minutes before the end of the race.
Article 30 Flags
If you are participating in the race, please understand the meaning of the flags displayed by the course marshals during the race. B.O.B.L. uses five types of flags to ensure smooth race operation.
At some racetracks, participants may actually go into the course marshals and wave flags. Please take this opportunity to remember this.
1. Japanese flag
Race start. Used at start.（The red light turns off when there is a signal）
2. Yellow Flag
Danger warning. This means that there is a danger on the course side or on the course. Yellow flags are displayed from one or two posts in front of the hazardous area. Riders should be careful when riding in yellow flag sections. Overtaking is prohibited.
3. Red Flag
Race competition canceled. When the red flag is waved, all competing cars must return to the pits. Please proceed off course with utmost caution. Overtaking is prohibited.
(Rider changes, refueling, etc. are not allowed in the event of a red flag during an endurance race.)
4. Black flag
If there is a problem with a vehicle or rider during a race, it will be waved along with a sign board with a bib number written on it. The presented rider must enter the pits immediately. Presented at the control line post.
5. Checkered Flag
Completion flag. The flag is waved at the control line post and the race is over.Vehicles that fall behind in a lap during the race up to the final lap will end the race on the lap where the checkered flag is waved. (In endurance races, overtaking after passing the flag is prohibited.)
Special Thanks Translation Lawrence ( ＠yokai.motorcycle.engineering )
