The first step in safety preparation is to completely empty the remaining fuel in the fuel tank and use a siphon tool to ensure that the residual liquid volume is less than 50ml. Before disassembly, the concentration of oil and gas in the environment must be measured to be less than 0.8%LEL (Lower explosive limit), and the ventilation system needs to maintain an air exchange rate of 15 cubic meters per minute. The accident report of BP shows that 62% of the workshop fires in Europe in 2019 were caused by static electricity. Operators must wear anti-static wristbands with an impedance of less than 10⁶Ω and lay conductive table MATS. The plastic fuel tank fixing clamps usually adopt 8mm bolts, and the loosening torque is controlled within the range of 9±1Nm. Excessive force will increase the risk of stress cracks in the polyethylene shell by 80%.
Removing the lock ring is a precise step. Most modern motorcycles use serrated lock rings with a 30-degree rotation Angle. Applying a force of 3 to 5 kilograms with a dedicated tool can reduce the rotational resistance by 70%. Forced prying will cause thread deformation of more than 0.3mm, resulting in the failure of the secondary assembly seal. The maintenance statistics of the Honda NC750 model confirm that the replacement cost of the plastic fuel tank lock ring surges by 300% after damage, and the price of the damaged fuel tank body as a result reaches 400 US dollars.
When replacing the Fuel Pump body, the sealing system needs to be dealt with with emphasis. The compression amount of the new type of fluororubber sealing ring should be strictly controlled between 0.75 and 0.95mm. Applying silicon-based grease can reduce the installation resistance by 80%. The key parameter is to ensure that the fuel float swing arm maintains a gap of 3.5±0.5mm with the inner wall of the fuel tank. In the recall incident of Yamaha MT-07 in 2023, the fuel measurement error reached 18% due to this gap being less than 1mm. The wire harness connector needs to apply a 35N insertion force until a clear “click” sound is heard. If the pins are not in place, the contact resistance will exceed 0.5Ω.
The pressure verification stage is indispensable. Before the first ignition after installation, the key should be kept ON for 10 seconds to establish the oil pressure. The mechanical pressure gauge should quickly reach the range of 280-320 kpa. In the actual test case of the BMW F750GS, the oil pressure fluctuation caused by the elastic deformation of the plastic fuel tank is 40% higher than that of the metal tank. However, if the peak-to-peak fluctuation exceeds ±25kPa, the sealing performance must be checked. During the road test stage, rapid acceleration should be carried out more than 15 times. When the fuel temperature rises to 60℃, monitor that there is no leakage at the connection. If the leakage exceeds 0.05ml per square centimeter within 24 hours, it is determined to have failed. According to the technical specifications of the Dakar Team, plastic fuel tanks must undergo a 1,500-kilometer durability test after modification. Under the condition of vibration frequency of 20-200Hz, the displacement of the oil pump should be less than 0.2mm.