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Discussion Starter · #1 ·
So I got this awesome new quad and at dusk/night I notice the the head pipe glows a nice birght orange.
I have heard several things;
1) this is standard settings from the factory
2) that is normal
3) Set the fuel/air mixture screw to 3 turns out
4) it's going to explode

I understand that this is a factory settign to meet emissions, but what is this doing to my quad?
Can I adjust the screw In/Out to correct this?
Is is correctable?
Can someone explain the fuel/air mixture screw setting? In/Out and what the effects are?

I am running stock right now with the spark arrested ehaust, air box lid removed, set to 2 1/2 turns out and it still glows but not as much as it used to.

Thanks in advance.

ORA. :rock
 

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Mine does that and its completly stock, not so much when I start to ride. I heard that the bike is lean, thats why its like that, and I also heard from a friend that works at a dealer, that its normal and its running good when that happens, His dirtbike with the same kinda motor does it just like my 450.
 

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Mine did that when it was stock also. (my 400 EX also does this) Any lean jetted bike will glow. It is the exhaust heat on a thin headpipe.

You SHOULD worry about removing the airbox lid on an already lean bike. Rejet it and it will run cooler.

Mixture screw is for low and off-idle settings. Your airbox lid mod will lean bike out at mid to upper range, and yes turning it out will help a little at idle.
 

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The pipe will glow a little even when properly jetted, mine used to glow alot but just a little now.

The headpipe is very thin, and you would see this if you took it off, this is part of the glowing problem. The other is the fact that is is way lean from the factory (especially in cooler weather) to pass emmissions and get the green sticker in Cali.

However, you have increased the lean condition by removing the sparky, and lit without jetting.

I would reinstall the parts untill you can get some jets.

A 45 pilot and 165 main should work and will only set you back about $8 bucks total. Then drop the clip on your stock needle to the 5th spot and enjoy the new found power.
 

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The lean condition will cause premature top end wear. Correct it and postpone cylinder replacement.
 

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You took a factory lean bike and made it leaner by taking off the lid. Put in a 165main on the 4th clip (stock needle) and it wouldnt hurt to bump up you pilot to a 45. Give it a shot. You might still glow but not as bad and you will have much better power and starting.
 

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My headpipe glows and i am running a 180 main with the needle on 4 or 5 so its probably a little on the rich side. I am running Noss intake with K&N/no lid with HMF full system, but I dont think it could be lean. Oh well, if mine blows up then I will just replace it with new better stuff.
 

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Discussion Starter · #11 ·
Thanks all for the help.

hugh grection:
Yeah. I kinda figured that out after all the info that has been coming my way about my setup. I'm slowly learning. thanks.

Ok. So,..Another small side rant.

Went to a local bike shop for the jets. They had the Main, but not the 45 pilot. No problem. They are nice guys. All they had was a 48.
Went to a local dealer, that was close to work but not Yamaha, asked them if they had a 45 Pilot for a Keihn(sp) carb.
He said- Yes. then asked what bike.
Me - Yamaha YFZ450 bad-ASS, kick-ASS quad. :lol
Him - OH. The jets we have don't fit that. Those are special jets. :evil

My rant;
Why would it matter what type of bike it is?
Aren't the keihn carbs pretty much the same as far as jetting goes?
I mean, you may not have one that will fit, and that would have been fine, but to say that the jets he has don't work with that carb, and they are special,.. isn't that a little off?


Again.
Thanks for all the help.
Soon to be stock again,...till I get the jets,...and exhaust.
 

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Tell the shop you need Keihin long hex jets. They are not bike specific.
 

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Discussion Starter · #13 ·
Thanks for all the help.
I went to a local Yamaha dealer on the way home and they had the 45 Pilot.

Installed tonight, will put the carb back in and package thins up and see how it runs.

:lol :rock :lol :rock :yfz
 

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A lot of the glowing is due to the fact that the factory header has such a thin wall. An after market header with a little thicker wall with the stock jetting glows less. Found this out on a buddy's bike.
 

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Originally posted by hondarules@Dec 10 2003, 04:09 PM
its normal i wouldnt worry about it. if it gets really bad maybe turn it off and let it cool down.
you need to worry about it, as the YFZ is usually VERY LEAN from the factory and is actually starved for fuel.

When you richen it up and let it breathe (baffle out/airbox lid off) it will become the rocket ship you are hoping for!
 

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I emailed yami on this 1.
1.bike is designed to run hot for max performance.
2.light weight material used on the header pipe.
3. high compression and high octane fuel.
4. heat disipating nickalsil lining. "that heat is gonna go places"
 

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YOu guys do realize that there are EXPLOSIONS going on inside your engine right?

The Exhaust valve opens before the explosion is completely over.
Part of every explosion in your engine happens in the head pipe.



400ex headpipes will glow at night, if you ever paid attention.

Yeah you need to richen it up from factory settings, but the glow will be significant, no meatter what you do .
 

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how hard is it to do this stuff? (correct the lean)

i better take it somewhere and start learning!
 

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Discussion Starter · #19 ·
Originally posted by liftedtaco38s@Dec 14 2003, 08:31 AM
how hard is it to do this stuff? (correct the lean)

i better take it somewhere and start learning!
If you have a garage it's easy.

Take your time and listen to what people say to do and you'll be fine. That's how I started learning.

If you take it somewhere, all they are going to do is tell you what they did and you won't know how to fix it if something goes wrong.

Jetting took me about 1 1/2 on this bike. Everything is almost right there in front of you.
On my XR I ahd to take the side panels, seat and tank off jsut to get close to the carb. That alone took about 1 1/2.

This is a great place to learn too. Alot of helpful hints and in depth instruction.

I've learn more than I knew before just from these sites, YFZCentral and Jetting.

Cheers :D
 

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cool, thanx :rock :yfz
 
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