[BobPeabody67]

I've got a 07 YFZ with an 04 motor in it. It got a full rebuild over the summer, and has had starting problems since. It's on its 2nd starter and 2nd battery. It's got a Trail Tech High Output stator in it, I checked the exhaust cam decompression pin, and that's fine. And I retorqued both cams just to be sure.

The only way it will start is if you put a battery charger on it. Once it's been running for 10-20 minutes to get warm, it'll start right up on the first crank. It will not start if it's cold without a charger on it.

When you try to start it without a charger it will crank over once, then wait a second, then crank over once and wait, and so on slowly increasing the wait between cranks.

When cold, the battery is at 12.74VDC +/- and drops to about 6-8VDC when cranking. But when it's hot, it only drops to 11VDC when cranking.

Any ideas on what next? If I wasn't still paying for it, I'd trade it off for a R...:bawl

 

[standard81]

Have you tried swapping the exhaust cam with a different one? It almost sounds like the decompression mechanism isn't working properly. Just an idea.

 

[BobPeabody67]

I haven't tried swapping it, but I did check it. When hand cranking, it stays out like it should, but moving the weight by hand, it goes right in like it should.


I'm terrible with correct terms, but I know wtf I'm talking about.:lol

 

[BobPeabody67]

Btw... Once it's started and runs for a few minutes, it runs perfect. It's just starting cold that's an issue.

 

[BobPeabody67]

Bump... Anything?...

 

[standard81]

You think it may be a crank issue? Have you turned it over by hand with the engine cold and with the spark plug pulled?

 

[BobPeabody67]

Yeah I have. That's fine. It goes around easy.

 

[standard81]

Strange. And you've load tested your battery? I wonder if the starter brushes are on the way out.

 

[BobPeabody67]

Yep the battery is fine. In fact the first one was fine too.

The only thing I can think of is if the new starter was bad from the get go.

 

[standard81]

That's a definite possibility. I'd try and swap with a buddy if that's an option for you. It's a quick job, and it would rule it out as a possibility, if nothing else.

 

[BobPeabody67]

All the moto guys around here are on dirt bikes. I'm kinda a loner in that sense.:lol



I can go to my shop, but I doubt they'll let me test a new starter out without buying it.:lol

 

[standard81]

I understand. It's tough to "borrow" something new sometimes...

 

[BobPeabody67]

Before I drop any dough on another starter, any probable cause to check the solenoid?

I would think if that was bad, it wouldn't run at all. But better to explore all possibilities.

 

[standard81]

If the solenoid was bad, you would likely just hear a click when you pressed the start button. One way to rule it out, though, is to bypass it. Just jump it. Touch the two large leads/terminals with a screwdriver. This will effectively jump the solenoid to see if it makes any difference. It's worth a shot.

 

[BobPeabody67]

Still a crank, a pause, and another crank like before.

 

[standard81]

Well, that means your solenoid isn't a likely culprit. All your connections are tight and dry? Just another thing to check. I'd be curious as to what the inside of your starter looks like.

 

[BobPeabody67]

All the connections are good. My headlights didn't work until I put the Trail Tech stator in, but they're fine now. That was my only electrical problem up until this point.

 

[BobPeabody67]

Is there such a thing as a Yamaha heater? Like diesel motors need to be plugged in in the winter or they won't start? Same principle, but on a YFZ motor.


That is if a 2nd new starter doesn't help.

 

[BobPeabody67]

Or like a coolant heater or oil heater that you plug in and it circulates, then unplug it and ride like normal.

Picking up what I'm throwing down?:lol

 

[standard81]

You could potentially use an inline coolant heater, or one of those heating pad things that bond to the engine, but neither are a very stout solution. I think your best bet is to figure out the problem, because it should always start relatively easily, and those heating devices rarely last long-- especially in extreme environments like on a quad...