NOT VMX - Yamaha WR450 electrical question

[Hoony]

Ok Here goes, need some technical help from Yamaha Men. especially if you have a later model WR450

A mate has a YZ450 mx'er he has recreational rego'd, he has bought the WR450 starter and electrics for it but apparently the WR450 has a tilt switch which sends a signal to the CDI to inhibit starting if the bike is not upright.

He has done some research and found that most guys just glue the switch in position (to simulate upright) and this cures it. he does not want to do this and would rather "bridge it out" now this seems simple enough but apparently you cannot just short the signal wire to "Earth" or "Supply" it need a small voltage above ground for a start signal and if its at supply this also inhibits it ( so its like a fail safe system)

i hope someone can help with the following so i can make up a circuit to supply the CDI with the correct signal.

- how many wires to the tilt switch (i am assuming 3)
- what is the color of the Supply wire
- what is the color of the Earth wire
- what is the color of the Signal output wire from the tilt switch
- What is the supply voltage (with respect to earth) to the tilt switch

[pokey]

Could be missing something but wouldnt you want to retain the YZ CDI for the curve?


 Either way the starter relay will be supplying the voltage  to the tilt switch

http://wr450wiring.blogspot.com.au/

[Hoony]

thanks pokey this will help me.

[sleepy]

I've done an R6 Yamaha just recently for use in a speedway car and the tilt switch bypass is quite a complex thing to do, far easier to take it apart and fill it with neutral cure silicone in the upright position.

[Hoony]

Hi Sleepy, yes they are apparently the same unit.

i am going to make a small circuit up to get around it. do you know what the voltage to the tilt unit is ( i am led to believe its approx 20Vdc but would like to confirm it)

[HeavenVMX]

Looking at the wiring diagram in Pokey's link which is never as easy to work out the function as a schematic. The starter circuit appears completely seperate to the CDI but does share the clutch switch which may not be present in a YZ.

You should be able to replace the starter cut out relay (10) which I assume has a tilt activated cutout mechanism with a normal relay you will probly need to put a resistor of around 2-4Kohms across the relay coil this will prevent the starter switch being damaged by the reverse spike generated by the inductive load of the relay when you open the switch.

You will also need to ground the output of the starter switch as you will also be missing the neutral  and clutch switches so need to bypass them (4,5 & 13).

[sleepy]

Hi Sleepy, yes they are apparently the same unit.

i am going to make a small circuit up to get around it. do you know what the voltage to the tilt unit is ( i am led to believe its approx 20Vdc but would like to confirm it)

From the manual it states. Upright .4 - 1.4 volts  Overturned 3.7 - 4.4 volts. A simple circuit with a couple of resistors may work, good luck.

[Hoony]

Thanks heaven & Sleepy.

i was thinking making up a simple voltage divider with 2 resistors to give the correct output (1 Volt) but will need to know the supply voltage, in the manual i read online it mentions a tester with 20Vdc so i could calculate with that.

Heaven, are you a electrical engineer or electronics tech, you have good knowledge in this area and i did not initially consider your thoughts on back emf, i am  thinking a reverse diode here, your thoughts ?

[sleepy]

Mostly the supply to all the sensors is 5 volt but you would be best to check it with motor running if possible. Keep the resistor values high, something like 8.2k and 2k should give about 1 volt from 5. Back EMF shouldn't be a problem. On the R6 the onboard diagnostics liked the complete sensor hooked up for some reason but the WR may be a lot more basic.