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2007 Yamaha YFZ450 wont start...lame


the_ry_guy
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So my 2007 Yamaha YFZ450 wont start...I narrowed it down to either the starter relay or the start button, battery is at full charge, and pushing the electric start button wont do anything, so i crossed the start relay with a screwdriver and she fired right up, shut it off, then tried the push button again, and it started, stopped it, tried the push button again, nothing, not even a click, now basically if you hit the start button 50 times it will crank finally but never the first time you hit it, so i'm thinking its either the starter relay going bad, or a faulty push button, any of you guys know a good way to test to isolate it down to just one without throwing money at it?

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Dream Car Giveaway

Hey I also have a friend that can get you a PDF service manual for free and it has electrical trouble shooting in it if you are good at that. It will give you the resistance, voltage and so on for each of the two parts you have narrowed it down to. So with the manual you should be able to determine which one it is. So let me know if you want the service manual and I will ask him to get it for you. And in the mean time here is a page with that has 04 and 06 manuals which also might have the same thing.

YFZ450 Garage

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Hey I also have a friend that can get you a PDF Service Manual for free and it has electrical trouble shooting in it if you are good at that. It will give you the resistance, voltage and so on for each of the two parts you have narrowed it down to. So with the manual you should be able to determine which one it is. So let me know if you want the service manual and I will ask him to get it for you. And in the mean time here is a page with that has 04 and 06 manuals which also might have the same thing.

YFZ450 Garage

That would be amazing Ballistik, if you can email it to me @ [email protected] I'd be in debt to ya man.

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If you figure out how the relay is wired, you can test the relay by tripping the signal tab. It recieves either a 12v+ charge when the start button is pushed, or it is connected to ground when the button is pushed. You can test the switch by checking for continuity when the button is pushed, if you can find a spot in the wires running out of the switch where there is connectors or something, you can test them at that point. Another thing you might want to do is just inspect the wires for damage or loose connections.

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Aw Josh you beat me to it! that's how you test a starter switch/relay. Most, but not all, Yammers are ground to start. Rem I said 'not all,' at any rate the book you just got should have a test procedure in it. And yes, the valves are CRITICAL on those and can cause many problems, including hard starting. Unfortunately, they have to be done at a shop since they use shims like a race bike or a Ferrari. Now had you bought a Raptor you could adjust the valves yoursel;f...

Edited by Raptor8
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Aw Josh you beat me to it! that's how you test a starter switch/relay. Most, but not all, Yammers are ground to start. Rem I said 'not all,' at any rate the book you just got should have a test procedure in it. And yes, the valves are CRITICAL on those and can cause many problems, including hard starting. Unfortunately, they have to be done at a shop since they use shims like a race bike or a Ferrari. Now had you bought a Raptor you could adjust the valves yoursel;f...

I get things right from time to time:biggrin: Why do you say that the valve adjustment has to be done at a shop? I realize that not everyone should be tearing into their engine, but I do my own valves, just measure the clearance, if they are off figure out how much they are off by and swap shims according to the difference. Make sure your timing chain is set and torque the cam caps properly. I know it isn't the easiest thing in the world, but I think that most people who are competent with a wrench could do fine. Besides, I don't think valves are keeping the start relay from recieving the signal from the start button.

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most ppl avoid valve adjusts on those cuz they require shims, and according to Yamaha, special tools too. You have far more skills than the average user so you can go buy a shim you don't have- most folks folks just let 'em go until they have burned seats.

A page from the Honda book: if it's ticking then it's not too tight- if it's quiet, then it needs to be examined.

That little shim box and tool kit represents a significant investment to the dealer cuz he has to buy the training as well.

In my travels I have found more and more HIGH PRO quads out there without the proper maintenance- and just one leaky valve can drive you into the Tylenol jar in the first aid kit.

Funny, my 1981 street bike is bucket and shim, but my Raptor 660 has adjustable tappets....

I have 2 Honda accords and they both make little ticking sounds that way I know theyre not doing damge by being too tight and not closing- plus it makes em great 'sleepers' harharhar

MOST OHC quads that are quiet in the head are too tight.:laugh:

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the starter Relay is a completely different problem which you covered very well!

I try to use a shotgun approach to a problem since I'm not there to see or hear it. Chances are good the thing needs a valve adjust anyway. Lack of this will eventually cause hard starting. I just wish ppl would read their OWNERS manual and buy a $ 15 shop manual!!!

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Indeed, it only takes me about 5 or 6 hours or to get down to Florence or Winchester Bay. I really want to hit Coos Bay this year. I am hoping to take a trip down to Oregon in the late spring or early summer, maybe sooner if the opportunity presents itself. I will be sure to let you know if I head down that way.

I know all to well the neglect that many of these four stroke sport quads endure. I have been telling many of my friends over and over that they need to check those valves. I even offer to help, but they insist that if it starts and runs then it is ok. I guess some people need to learn the hard way.

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  • 2 weeks later...

Im going to sand lake, oregon the weekend of the 29th, id like to go to winchester bay more often but its about 6 hours for me too, and sand lake is only 3. going to tahuya for memorial day too, hope i can get a camper spot lol. Im getting a new start button for the quad here soon, hopefully before the trip, and you guys are right, i do need to get it in and get the valves checked, it hasnt been since ive owned it. about a year now, and who knows before that...

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  • 4 weeks later...

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