Sky Blue Wire?

[MY-BLUE-BEAST]

I ride a 2004 WR450F, i have done all the free mods to it, and then some. The only thing i havent done yet is the Sky Blue Wire. What is this, what does it do and have any of you had success with it? let me know thanks....

[The Hopper Show]

i believe it makes your bike fire every stroke instead of every third stroke. i say leave it.

[MY-BLUE-BEAST]

I agree man, i decided to try it today, it didnt help at all really. I noticed a good acceleration, but it starts to cut short as I worked through the throttle. and after some reading, i found out that it really just helps out the idle and should help with starting the bike, but i noticed nothing in that field. so i replaced the wire and thats where it will remain.

thanks.

[MANIAC998]

On my '06, it allowed the bike to fire on the first revolution of the crank when using the starter button. I videotaped it to prove it to some ThumperTalk members who said it doesn't do a thing. That shut them up!!! Our race series was 7 races long, and I holeshot or nearly holeshot all but one round. Maniac

[Sknight]

As above, during e-start it allows the engine to turn over three times before the CDI fires, it makes life easier on the starter and battery because without ignition the starter can come up to full speed much easier. Especially useful when the engine is hot.

The CDI fires every stroke when kick starting though, so if you mostly kick start you'll not notice it.

[SXP]

As above, during e-start it allows the engine to turn over three times before the CDI fires, it makes life easier on the starter and battery because without ignition the starter can come up to full speed much easier. Especially useful when the engine is hot.

The CDI fires every stroke when kick starting though, so if you mostly kick start you'll not notice it.

Confusing post......

Stock (with the blue wire connected), when you attempt to estart the bike, the motor will turns a couple of revolutions before the bike will fire.

With the blue wire disconnected, the motor will attempt to fire up on the first revolution when using the e-starter. Doesn't always happen as there are other factors in play here, such as jetting, hot/cold engine, etc., but IMHO it's a worthwhile mod.

On the other hand, disconnecting the gray wire for trail riders who do a lot of very technical riding, IMHO, is a useless mod....just sayin!

[MY-BLUE-BEAST]

Unless you put the grey wire on a toggle switch like I did. I ride a lot of tactical trails in really tight situations. It makes life easy when you can turn it off to haul ass to your spot, and then switch it over to more tourqe and easier control when you get there. And it works great.

[grayracer513]

Are we talking about the correct wire?

The Sb ("sky blue") wire at the CDI harness connector connects to a blue/white wire in the harness on US models. This runs to the neutral switch, and I don't see how the CDI can get a voltage signal from that during starter operation, as that lead goes to a ground.

On the other hand, there is a Blue/White lead running from the CDI connector to the CDI which connects directly to the starter relay circuit by means of a Blue/Black harness lead, and this definitely does see voltage when the starter circuit is active.

See this post and thread:

https://www.thumpertalk.com/forum/showthread.php?p=5594723

[MY-BLUE-BEAST]

I connected the wire again, its not worth it. I don't understand what the big deal is, maybe it helps with some WRs, but not mine.

[SXP]

I connected the wire again, its not worth it. I don't understand what the big deal is, maybe it helps with some WRs, but not mine.

See Gray's post above. The quick starting mod is the blue-white wire mod. My bad for confusing the sky-blue with the blue-white. I have my sky-blue wire connected and the blue-white disconnected.

[grayracer513]

Yup, disconnecting the sky blue (CDI side) will do nothing except make the CDI think that the bike never goes into neutral.

[MANIAC998]

My apologies guys. I got the wires wrong. Sorry to lead this thread astray. Blue w/White trace is the correct one for getting the bike to fire on the first revolution. My bad!!! Maniac

[Sknight]

Confusing post......

Stock (with the blue wire connected), when you attempt to estart the bike, the motor will turns a couple of revolutions before the bike will fire.

With the blue wire disconnected, the motor will attempt to fire up on the first revolution when using the e-starter. Doesn't always happen as there are other factors in play here, such as jetting, hot/cold engine, etc., but IMHO it's a worthwhile mod.

On the other hand, disconnecting the gray wire for trail riders who do a lot of very technical riding, IMHO, is a useless mod....just sayin!

All you did was repeat what I said with different diction, leaving out why a few revs before firing is helpful, but thanks for trying.

[MY-BLUE-BEAST]

ok, so the blue and white wire is what i should be looking at?

[grayracer513]

Yes, but be careful; there's a blue/white CDI lead that connects to the Blue/Black harness lead that IS the starter signal wire that you're looking for, and a blue/white harness lead that connects to the sky blue CDI lead that is NOT what you want (that's the one you fiddled with already).

[MY-BLUE-BEAST]

cool, thanks. Ill look into it tonight since i dont have to work tomorrow. ill let ya know how it goes.

[SXP]

All you did was repeat what I said with different diction, leaving out why a few revs before firing is helpful, but thanks for trying.

Huh? I said nothing of the sort. How/why would the extra revs be helpful or less stressful on the starter? If anything, you are putting more wear and tear on both items by allowing them to crank longer.

[grayracer513]

The original object of the two dead cycles seems to have been to guaranty a certain amount of crank inertia before the first spark occurs. What Yamaha was apparently trying to avoid was the starter launching into action against the compression stroke and getting kicked back 30 degrees into its rotation.

But it's notable that, one, no one else does this that I know of, and two, that there is a torque limiter in the starter clutch to avoid having the starter get hit too hard.

For race starts with this mod, I would have the bike in gear and pull it back against compression (which would actually be the bottom of the power stroke). That would give the starter one completely free revolution to run up in.

[Sknight]

Huh? I said nothing of the sort. How/why would the extra revs be helpful or less stressful on the starter? If anything, you are putting more wear and tear on both items by allowing them to crank longer.

Cranking against a cylinder trying to fire is far harder than cranking against compression alone. By spinning a few revs before the CDI fires the mass of the rotating assembly has enough inertial energy to help overcome the cylinder firing.