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donved

New Yamaha YFZ 450 problems.....

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Hope that there is someone out there that can shed some light on this... My brother just bought today an 08 YZF 450 and while we were messing around this evening kinda "breaking it in" We noticed that the exhaust was so hot that it was glowing RED! during the few hours we were riding it around the fan never did kick in and all awhile we were questioning this...As it turned darker out we noticed that the pipe was red hot! He's thinking that there is something wrong and will be calling the dealer up first thing.. Has anyone out there ever heard of this happening to the YFZ's before?

Any input would be great! Thank you,

Don

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Were you moving when it turned red? My uncle's WR head pipe will glow red if you leave it running and sitting still for any given amount of time. It does it during the day too you just can't see it in the light.

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It has a lot to do with the what kind of fuel you run.. i've also heard that if one runs lean that it causes it more frequently. My friends 08 started that after his new HMF full system. another friends started after race fuel. Mine has never done it. Both of theirs stopped after being EGA'd and were apparently running too lean.:confused: so if you live in high elevations and it still has the stock non-adjustable air fuel screw, that may be whats causing it.:wink: but egt's that cause glowing pipes aren't directly related to Engine temp as whole, just means fuel mixture is lean for the type of fuel. get a fuel screw and get it adjusted and jetted right for your elevation, fuel, intake and exhaust. I'm no mechanic, but i beleive that would releive the problem and most of all add life to your valves and topend... ESPECIALLY if its running lean!!

Good luck with it and keep us posted on what you find out!!

Whats your riding elevation in Oregon??:wink:

and Bot, has that WR still have the bone stock non-adjustable carb? or has it been adjusted and still does it?? let me know:biggrin:

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It has a lot to do with the what kind of fuel you run.. i've also heard that if one runs lean that it causes it more frequently. My friends 08 started that after his new HMF full system. another friends started after race fuel. Mine has never done it. Both of theirs stopped after being EGA'd and were apparently running too lean.:confused: so if you live in high elevations and it still has the stock non-adjustable air fuel screw, that may be whats causing it.:wink: but egt's that cause glowing pipes aren't directly related to Engine temp as whole, just means fuel mixture is lean for the type of fuel. get a fuel screw and get it adjusted and jetted right for your elevation, fuel, intake and exhaust. I'm no mechanic, but i beleive that would releive the problem and most of all add life to your valves and topend... ESPECIALLY if its running lean!!

Good luck with it and keep us posted on what you find out!!

Whats your riding elevation in Oregon??:wink:

and Bot, has that WR still have the bone stock non-adjustable carb? or has it been adjusted and still does it?? let me know:biggrin:

Yeah, he is still running stock everything minus the baffle. It doesn't do it while riding, just if he lets it sit and idle for a long time. It is not visibly red during the day, just at night. I can tell you now he is running to lean. Stock jetting is set for sea level but we ride up to 10.000 feet.

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9 times out of 10 u are running to lean, u need more gas flow to the engine.

You Sir are Correct.....I dont believe Ive seen "you need More Gas Delivery" in a long time....

Before you consider fine tuning your carburetor there are a few things that have to be done.... First you need to install a clean air filter... Second you need to insure the float level is properly set..... If the gasoline level is set too high or too low properly jetting your bike will be impossible......... A high float level will cause it to run rich and a low level cause it to run lean....

Don’t go out and try to jet your carburetor with the gasoline that’s been sitting around in your jerry can for the past month... Gasoline degrades over time so you’ll want to start with a fresh batch..... While I’m talking about gasoline remember that different gasoline will change your jetting requirements. If you normally run race gas, straight or use it to cut pump gas, you’ll want to be sure you have it in your tank when you head out to tune the carburetor....You also need to be aware of any potential mechanical problems that can imitate poor jetting

Oh,,,,and here is a tip....when changing needle positions try using a pair of Hemostats to keep the throttle valve spring and collar at bay.....:wink:

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Yeah, he is still running stock everything minus the baffle. It doesn't do it while riding, just if he lets it sit and idle for a long time. It is not visibly red during the day, just at night. I can tell you now he is running to lean. Stock jetting is set for sea level but we ride up to 10.000 feet.

Are factory Bikes jetted from 0-3000 Feet????? Try putting that Baffle back in.....Might create just enough Back Pressure to make it right again.....

Temperature, Altitude, Humidity......

Temperature-changes in air temperature will have the greatest effect on our jetting. As the air temperature gets colder the air density increases. The air molecules become less active ( move around less ) and therefore take up less space. Because they take up less space more air, and therefore more oxygen, can fit into a measured volume of air as the temperature decreases. As the temperature drops the engine will begin to run leaner and more gasoline will need to be added to compensate. As the temperature increase the engine will begin to run richer and less gasoline will be needed.

Altitude- Again this is an issue of air density. At sea level atmospheric pressure is around 15 psi and as the altitude increased the atmospheric pressure decreases. Because less pressure is exerted on a measured volume of air as the altitude increases the air molecules are able to relax and they take up more space leaving less space for additional molecules. The higher the altitude the less air in a measured volume and therefore less oxygen present so jetting will have to be leaned to compensate.

Humidity- Humidity is a measure of how much water vapor is in the air. The higher the humidity the less space there is for additional molecules of air and therefore oxygen. As the humidity increases there is less oxygen and therefore the engine runs richer. Jetting that may have been spot on in the cool dry morning air may start to run rich as the temperature and humidity increase over the course of the day.

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leave it alone, it is common to most quads, you just don't see it during the day.

Yamaha mechanic.

READING the owner's manual may help, this is NOT a lawnmower.

:wink:

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i agree with raptor 8. leave it alone. mine does the same. i live in kansas. mine turns bright red. took it to the little sahra pro shop. they said they would put it on a dyno checked out just fine.THE ONLY WAY TO BE SURE IS TO PUT THE THING ON A DYNO BY SOMEONE THAT KNOWS WHAT THEY ARE DOING!

Edited by joshwgrossenbacheryfz

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i bought 08 YFZ450 and mine did the same plues when i would get on it it would bog out and die took it in to the shop they had it for 4 weeks tryed everything on it they rejetted it and couldnt find the problem so they started swapping parts found out my throddle sensor was bad they told me they rejetted it and they ajusted the Air/Mixture Screw havent had a red exhaust since then they told me it was to lean from the factory

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sounds like someone was having a bad day at the yamaha plant it sucks that someone would not take more pride in there work. Just takes one person to screw up a this is what can happen! The big question is how many more yfz did they do this to.Sounds like the shop got it right. Don't understand why they would rejet the carb was the main not right size ? Or did the factory have wrong jet in the carb.

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All machines come from the factory jetted for sea level. Yamaha sends the a bit on the lean side anyways, and when you start climbing in elevation it just messes with stuff even more.

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that's kinda strange.....It it's fuel infected, it'll have a throttle position sensor, but not if carbed. carbs have air mixture screws but fuel injection does not, at least not enuf to compensate for altitude. and 4 weeks? wow.

we commonly rejetted them here for 4000' alt but most all will still glow red in the dark. Adam mentioned an EGA {exhaust gas analyzer} maybe the bike shop doesn't have one but most car dealers and better independents do. that'll tell you if it is lean in about 2 minutes..... Actually bringing them up the hill should make them run rich, not lean, since the air is thinner. it gets less air but the same amount of fuel.

Edited by Raptor8

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My header pipe did the same thing( '07 DVX/Z400);but it glowed orange hot after I installed the HMF full system.I had it jetted the way HMF said to but it took a rejet kit(Dynojet-stage2)to get it right.My quad has a ThrottlePositionSensor(TPS) and it's carbed.The way I understand it's for the ignition advance.I've seen a bunch of stuff for the YFZ;carb wise.You might check out www.F2racing.net ;they have a kit that's supposed to be really good.I also seen an article in www.Quadmag.com about a timing change you can do to make better power;all you do is advance or retard the timing one tooth.Hope this helps

Edited by dirtdevil96
fixed so links work

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Thanks for the updated info! I have not seen a carb [from Yamaha anyway] with a TPS on it.

Our altitude varies so much here that we try to strike a happy medium...

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