Starting circuit cut-off relay problem

Hi All,

Has anyone else had problems with the Starting circuit cut-off relay? Its the little black box at the back of the airbox.

My 450 has decided it wont start and after following all the info have found it to be faulty. A couple of whacks with a screwdriver and its back in business, but then it tries to start when I power on now .... :D

Have ordered a new one, but it will have to come from japan :):D

Am I the only one?


I have not heard of this problem yet. I think you are the first. The relay should be inexpensive. You may be able to get one from an electronics store if Yamaha does not have any in stock yet.

We took ours out when we first prepared the WR, it serves no useful purpose, there is a lot of fluff in the electrical system on the WR. Also removed were headlight,engine stop button (actually we put it back on as the start button after the start button popped out)clutch switch,diode, starter relay diode,cut off relay,tailight,neutral switch,main switch (we use the light switch as the main switch)and all associated wiring. Except for the woodruff key we have had no mechanical or electrical. After the woodruff key broke our dealer replaced the crank and rotor (since it had less than 1/2 mile on it) and have had no problems since put I still ordered the "slip" gears just to be sure. Remember "no dnf's" :)

Thanks Wrench,

Sounds like you would have had to do a bit of re-wiring to get everything to work though :D

In the end I got the genuine part $55 :) the same day I found a Hella relay the same for $7 :D oh well, at least I now have a spare.

Cheers Deano

I don't know that much about electronics but my bike wont hold a charge very long.I charged it a week and a half ago and rode it all day no problem.I go out tonite to start it and nothing the little red light wont even come on :thinking:I kicked it and rode around the neihborhood and when i came back it still would not start. Where do i start to check for problems?

Did the red light come back on after a ride around the block?

ie. is there any charge going to the battery

If not, put a multimeter across the battery while its off, check voltage, start the bike up (kick start) and check voltage again, it should rise to around 13-14 volts.

If it stays the same then your charging circuit sounds funky

If it rises then charging circuit is OK, check battery connections, fuse connections etc, and if all is fine there start looking at the main start relay connections (presuming you have checked the main on/off swtich first).

The manual goes through all this step by step and is pretty good for diagnosing problems.


the battery is a low life one i just charge it before i ride (the night before) on a 12 volt 2 amp charge... takes about 10-12 hours so then when i wake up a quick push of the button turns it over with no problems at all.. it lasts through out the day then dwindles off.. the 3rd day theres still juice but i have to push the button down for about 3 seconds before it cranks over :) nothing abnormal it seems :D :D


I have read of several people with this issue, personally, I ride every weekend (or try to at least) and to date have not had to put the battery on a charger yet !!!! the thing just cranks and cranks.

I presume they are the same battery down under as the spec is specifically for a WR450 ...

Oh well :)

Cheers Dean

Concerning battery charge...I rode last weekend after bike sat in garage for 3 weeks. Got to the trail and it fired right up w/button. Twice during the day I dumped it going up a steep hill, bike upside down gas pouring out. Got it back on its wheels, pulled in the hot start and spun the motor in 20 sec bursts for about 2 min before it cleared enough to fire (I could not imagine kicking it over). When I got home I put the trickle charger on it to make sure I had a full charge for the next day and after 1 minute the charger light turned green - full charge! I wouldn't trade the button for 15 lbs. :)


Exactly the same experience I have had :)

I wouldn't trade the button or the bike for quids


PS. am seriously looking at the Z-start clutch ... sounds like a lot of fun to me ....

I ride almost every weekend also but have slowed to about twice a month because of the heat and the dust.I bought the bike used with about 190 miles on it .The guy i bought it from also had a KTM ,i'm sure he didn't ride it every weekend.So maybe they go bad if you let them set!I even bought one of those trickle chargers because it would not take a charge from the big charger.The trickle charger worked.This is the first time it has gone fully dead. And to answer anouther question yes when i came back from my ride around the block the red light would work but not start. :)

All batteries like being used and charged often, so if its been sitting around discharging on its own, they do lose their max capability fairly quickly....

it sounds then like your charging is OK, does the starter work at all after the run, ie., even a slight turn? if it does then I would certainly start looking at the battery, see if you can get a mates battery, or even put a set of jumper leads off your car onto the battery. If that all works, then I would say the Battery is probably toasted.


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