Need help with YFZ-450

[Chris Halvorson]

Up until lately, this has been a great quad...but I am sure it isn't the quads fault. Here is my issue. The quad will turn over...but will not fire. Here has been the recent activities with this quad:

-Two weeks or so a go, I went up to the mountains with the YFZ-450 and had a snow day. I came home and accidentally left the key on and drained the battery. It seams to hold a charge...but I will bring a volt meter home from work tomorrow to see if I have a bad cell. This could be the issue with the quad not wanting to start.

- I have changed the spark plug 2 times, checked gap, getting fuel. I have checked all the fuses..they are OK. I haven't checked for spark yet..and I should have done it when the last spark plug was out.

- Gas is fresh.


The quad does seem to not turn over as fast as before...so I am thinking it is the battery not putting out enough volts (on cell going bad). What does everyone else think? Thanks for any input.:beer:

[MtnRunner]

Battery voltage is critical on the 450 for start and ignition. Sounds like its time for a new battery.

[Chris Halvorson]

Thanks Mark

[sonofmayhem]

I hook up a jumpstart box to my predators when I haven't run them in a while. It really helps get them started quicker.

[vb]

i notice that if my predator is really cold or has sat for a really long time (4 months) i need to get the thing to spin faster then the brand new battery can go. also noticed that i can "help" it if i manually "choke" it using my hand to cover the carb. gets my hand wet and stinky tho

[Chris Halvorson]

I think there is a bigger issue here. I don't think I have any spark...or it is really weak. So there must be other issue's. This sucks.

[vb]

bad plug?

[quadracer812]

if the battery is a stock one, replace it. what year is the bike also. my bike has the cam turned and a piston in it and it killed the stock battery very fast turning over that much compression. when yamaha first put these bike's out there was a 6 month back order on the batteries and they are speacial size and no aftermarket companie was making them yet and alot of people had to get the aftermarket air box for a normal sized battey, but there is now many aftermarket batteries now

pull start your bike behind a truck. it may still run like crap with a low battery, this is a common problem with a yfz, get a battery or if you never want to go through this again, get a kick start kit

[mtntj]

Check your plug wire, is it seated good on the plug? Now the silly question, do you have a on/switch other than the key , and if so is turn on? I have done this my self, my friends pointed it out right before I started to take the whole thing apart.:shrug: :beer:

[Chris Halvorson]

Plug & plug wire is good. It is a 06 model. I think the TPS is messed up or the Stator is out.
I see no need to change a 80.00 battery that is putting out 12.57 volts...but I could be wrong. What is everyone else's batteries putting out?

[Chris Halvorson]

Well, found out what my issue was today. There is a sensor in the throttle (not the TPS) on the bars. It was out. From what RMC told me...it is pretty common on all makes for this sensor to fail. They gave me the option to bypass it...and that is what I did. This sensor was for a sticking open throttle. I most likely will get a clip kill switch.
John Olds looked at it as well for me and worked on the jetting. He put a 148 pilot jet in and a bigger leak jet in (makes it a smaller hole so the accelerator pump keeps gas longer). This quad was just fast before. Now it is just wow.

So just keep this in mind if you start having issues with starting.

Thanks for all the comments and advice.

[quadracer812]

I have a honda throttle box, which I had to bypass mine also, baldwin makes conectors which just have a u shaped wire if you don't want to cut wires.

and I guess I read your first post wrong, sorry I thought it said it would not turn over

[Whitey]

Well, found out what my issue was today. There is a sensor in the throttle (not the TPS) on the bars. It was out. From what RMC told me...it is pretty common on all makes for this sensor to fail. They gave me the option to bypass it...and that is what I did. This sensor was for a sticking open throttle. I most likely will get a clip kill switch.
John Olds looked at it as well for me and worked on the jetting. He put a 148 pilot jet in and a bigger leak jet in (makes it a smaller hole so the accelerator pump keeps gas longer). This quad was just fast before. Now it is just wow.

So just keep this in mind if you start having issues with starting.

Thanks for all the comments and advice.

I'm having a problem getting a 2000 Grizzly 600 to start. Would this sensor also apply to Yamaha's? :shrug:

thanks,
Whitey

[Chris Halvorson]

Is there a wire(s) coming out of your thumb throttle? If there is, this could be an issue. I am not sure how they bypassed my setup, but I would be more than happy to look into it for you.
I think these quads/motorcycles are getting too much electronics on them. I was glad to get rid of my Raptor...everything on it was electronic. Only good thing about it was it always started, spark plug was easy to get to and the valves were easy to adjust.

Quadracer- no problem, I most likely wouldn't have been able to fix it anyway. They did some jetting...and it really runs great now. I do appreciate any advice from anyone on this board. It is hard to diagnose someones problems over the net...that is for sure. LOL

[MtnRunner]

Glad you got it figured out. Sounds like the jetting really brought it alive. I'll have to ride it again some day. We just got back from riding in Farmington area. Lots of fun down there. Glad you kept the 450 and sold the Raptor :)

[Chris Halvorson]

Ginny really didn't like the Raptor...she said it felt too fast. Funny thing is her bike will smoke it. LOL

I would have never figured that there is a safety switch in the throttle...?

[Whitey]

Is there a wire(s) coming out of your thumb throttle? If there is, this could be an issue. I am not sure how they bypassed my setup, but I would be more than happy to look into it for you.

..... getting too much electronics on them .......

Haven't look this morning, didn't hear of the fuel throttle cut off till you put that up and I read it last night. (Should have looked here sooner).

I've got a new plug, coil, (last year), new plug cap, new CDI after all the wiring checked out, (juice, continuity), cleaned, filed contacts on the kill switch yesterday and rechecked the wires, they're good.

Still no juice to the coil, (wire is good) and getting juice at the CDI.

I'm stumped. :shrug:

Appreciate the offer, I'll look into the throttle today. If you think you could find the problem, I may take you up on it. This is going on three weeks now. :(

[Chris Halvorson]

This sounds just like what happened to mine. Everything is good, but getting no spark.

[quadracer812]

all you need to to do is cut an splice the two wires together and you are good to go, they had put this one alot of yamaha's, my 01 blaster did and we just spliced it, but I didn't want to cut the yfz so I got the conector

[Whitey]

Checked it out and there isn't a cut off switch on the throttle. The housing for the cable is empty except for the cable/arms/etc.

Only wire on the throttle side is for the 4x4 engage, a push button that activates a relay for the 4x4.

I've got some more checking to do and am thinking I'll try the rectifier/voltage reg. The wife's is a 200 Kodiak 4x4 and the part #'s are the same for the rectifier, only difference I see is in the elec. schematic; Kodiak shows 5 wires and the Grizzly shows 6, but parts #'s are the same?

Anyway, when I have time, will pull the one out and try it if it looks like it'd work. Also, relay's for the starting circuit cutout is the same as the other relay, so, will swap them around and see.

Hope to find it before summer. :(