well i have two questions.

1. I have a knocking sound coming from my engine when my bike idles in nuetral and has a problem idleing but will idle ok when clutch is pulled.

2 I replaced my guages with the f4i b/c my old rpm guage quit working now the new guages work fine except the rpm guages. What could it be is there a sensor that reads the rpms i could replace or something.
any help would be great

 

Normally I would say it is your chain tensioner going bad. Mind had a knocking sound that went away after it warmed up (Can't remember if it stopped when I pulled the clutch but the bike was close to warmed up when I left). Yours could be worse. But I changed the tensioner and had a pro tension it correctly and it runs smooth now.

Not sure about the RPM sensor.

 

your tach is connected to a wire, that usually connects to one of your ignition coils, look at a wiring diagram, because it sounds more like a wire is loose somewhere.

I think the wire for the tach goes to an ignition coil, then it goes to another series of wires for hte fuel pump, and also splits to the CDI box too I think.

 

How many kays/miles on your bike?. There are lots of things that can cause an engine to knock, including petrol. But if a bike is idling so low (or car for that matter) to the point where its almost cutting out, then you will hear a knocking sound coming from the motor. If it goes away when you raise the revs (without the clutch) then your problem is one of idle adjustment.

 

Without hearing the knocking it's hard to say what it might be. Try using a mechanics stethascope to localize the sound. You can also use a long handled screwdriver. Pressing your ear against the handle of the screwdriver while placing the tip against different parts of the engine. Naturally this can be really dangerous to do while the engine is running. An actual mechanics stethascopeis the best way to go.

As for the Tachometer, it gets its signal directly from the ICM (Ignition Control Module). No other devices are attached to this wire.There is a Yellow/Green wire from the ICM to tachometer which has a pulsing signal that varies with the RPM of the engine. You need a meter that is capable of capturing peak voltage. It's supposed to have a peak voltage of 10.5v minimum. A regular meter is just going to show the average voltage because the duration of the signal is so short the meter can't respond quick enough to read it. In keeping things simple, check the things you can. Make sure the connection to the back of the guage unit is good and not corroded. Check the connection of the Y/G wire coming from the ICM which is located on the right side behind the rear side cover. It's possible that the ICM is bad, but more likely a bad connection or even a broken wire. You should be able to test continuity through the Y/G wire with a standard meter. That will tell you if it's broken

Good luck...