My Yamaha 2008 YFZ-R1 has done 26,000 km or 16155 miles. Its running really rough, starts on 3 cylinders, the fourth (unsure which one it is) cylinder fires up every now and then when riding and it feels ok when its firing, but still slightly under powered. At all other times it just runs on 3 cylinders and feels like garbage.
Pulled the ignition coils out on the weekend thinking it could be them that's causing the problem. The ignition coils are made by Mitsubishi, found these spec for them on this web manual: Electrical Specifications - Yamaha YZFR6X(C) 2008 Service Manual [Page 43] | ManualsLib
Model/manufacturer: F6T568/MITSUBISHI
Minimum ignition spark gap: 6.0 mm (0.24 in)
Primary coil resistance: 0.85–1.15 Ω
Secondary coil resistance: 5.01–6.78 kΩ
When I tested them with my multi-meter, I got the following readings (left to right across the head):
Cylinder 1, 2, 3, and 4:
Primary 1.4 Ω (either 1.3 or 1.4 across each primary)
Secondary 5.7 kΩ (either 5.65 or 5.7 kΩ across each secondary)
When taking the rubber boot off the bottom of the 4th coil, the plastic shielding underneath cracked off really easily (so now i have to buy at least one more).
Looks to me like ALL the primaries are reading out of spec (resistance too high).
Zero resistance would indicate a shorted coil while a high resistance reading would indicate an open coil.
Would this high resistance reading be causing the coils to malfunction? or not deliver the right voltage to the spark plugs and in turn be causing my issue?
All the readings on the secondary seem fine! If one of the coils was arching to the motor, would you be able to hear this like a ticking sound?
Pulled the ignition coils out on the weekend thinking it could be them that's causing the problem. The ignition coils are made by Mitsubishi, found these spec for them on this web manual: Electrical Specifications - Yamaha YZFR6X(C) 2008 Service Manual [Page 43] | ManualsLib
Model/manufacturer: F6T568/MITSUBISHI
Minimum ignition spark gap: 6.0 mm (0.24 in)
Primary coil resistance: 0.85–1.15 Ω
Secondary coil resistance: 5.01–6.78 kΩ
When I tested them with my multi-meter, I got the following readings (left to right across the head):
Cylinder 1, 2, 3, and 4:
Primary 1.4 Ω (either 1.3 or 1.4 across each primary)
Secondary 5.7 kΩ (either 5.65 or 5.7 kΩ across each secondary)
When taking the rubber boot off the bottom of the 4th coil, the plastic shielding underneath cracked off really easily (so now i have to buy at least one more).
Looks to me like ALL the primaries are reading out of spec (resistance too high).
Zero resistance would indicate a shorted coil while a high resistance reading would indicate an open coil.
Would this high resistance reading be causing the coils to malfunction? or not deliver the right voltage to the spark plugs and in turn be causing my issue?
All the readings on the secondary seem fine! If one of the coils was arching to the motor, would you be able to hear this like a ticking sound?