Bike not running right? Our experts have the answers to the toughest questions
Bimota YB8
Q I am the proud owner of a 1991 Bimota YB8 which I have had for about six years. It has always run very well... until now. There is an issue whereby the fuel pump will only activate for a few seconds when the ignition is turned on. The engine starts and runs until the carbs run out of fuel. If the ignition is switched off and back on again the same thing happens, time and again.
The fuel pump has been replaced with a quality Mitsubishi unit which runs as it should when connected to an external power source. The problem appears to stem from the fuel pump relay which cuts power to the pump after about five seconds, and will not power up again until the ignition is switched off and on.
Would you say the relay is faulty, or is there something else telling the relay to cut the power perhaps?
A Ferret says: The YB8 runs aYamaha FZR1000 EXUP engine, so I looked at the EXUP factory manual. Be aware Bimota might have changed some wire colours.
It seems like the relay isn’t getting a pulsed earth from the igniter when it’s running. When ignition is switched on, your relay runs for a bit to fill up the carbs but isn’t getting the message to run the pump after the bike starts.
Using an extra length of suitable wire, temporarily bridge the blue/red wire at the ignitor to the battery negative (this wire runs from the fuel pump relay to the igniter unit). With the ignition on, the pump should now run all the time. If so, the problem is in the igniter. If things are still as before or it doesn’t work at all then either: the relay’s had it; there’s a connection problem with blue/red wire; or the wires from relay to pump are suspect.
Gauze gone, lost cause?
Q The filter gauze on my fuel petcock has deteriorated. Can it be repaired? I was hoping to buy a mini-gauze filter and attach it somehow.
A Pete O’Dell says: There are a number of vendors on eBay and elsewhere selling replacement gauze fil
