ok i have put back on my stock intake, have the cam mod done. have a dr. D pipe.

i have also put in a spark arrester/ quite core.

here is the deal, the head pipe is no longer getting orange even in the dark and the fan comes on. it does not like to idle too fast or idles for a while then dyes.

right now i am running a 45 pilot and i think a 155 main jet.

any ideas? is the carb plugged? float stuck giving too much gas?

another thing i see going on is it is wanting to keep all the oil in the res. but i think it has always done that.


thanks


danno

The head pipe glowing orange is not good. I would say that your MJ at 155 is a little small for using a slip on. Buy the James Dean jetting kit it will solve your jetting issues and take all of the guess work about jetting.

Get the service manual it will pay for itself the first time you use it.

head pipe orange up to about 6in is fine anymore then that you are way to lean. What needle are you using?

stock needle but its on the top clip i think going to move it down 2 notches tonight. thinking then i should be fine with a 165-168 jet im hoping anyway because going out tomorow.

I gotta disagree with you eddie. I've had my quads dyno tuned, with a sniffer in the tail pipe. I know for a fact my jetting is right. There is no glow on my pipe. Your way too lean if your glowing red. Sumpthin aint right if that happens!


danno, why do you have the stock intake in place with a pipe and the cam mod done???

make sure your gas cap isnt fouled and venting. that will cause it to dye if negitive pressure is in the tank.
the head pipe not glowing and fan running could be a faulty thermo switch causing the fan to run keeping the engine cool.
but the head pipe not glowing? Joe this isnt fuel injected, so you and your no jet ltr go away
mine glows about 3-4 inches when idling or running hard at night. Id inspect your carb, move the needle down to 2 clips from the top. bump it up to a 172 and 45 pilot. 2 turns on the fuel scew <--- make sure that hasnt backed out. has giving others problems in the past) may want to do a compression check.

I was talk'n about my Z ya putz...the LT-R aint been done yet! But my V-rod got dyno'd a few weeks ago. No glow on those pipes either...

I would hope your street ride does not see the types of loads that a dirt race motor would/could... I bet if the quad was cruising on the blvd it would get near as hot Just sayin

The YFZ pipe glowing is perfectly normal... called yamaha to verify when I first noticed it, when the bike was new. I was even running a 180 jet, which was a bit fat! I had a stalling issue when I lost my fuel mixture screw... might want to check that like Steven said.

if only we lived in AZ eh?? id love rid'n my quad to work!!!

to me, what danno is sayin is totaly normal, if im reading it right. on all of my quads, and my street bike, the fan cycles on and off, and the pipes dont get that hot. thats what a thermostat does, it tries to maintain a steady/constant temp of the engine coolant, and the fans and the thermostat regulate that! just like they do in your car.

there is no T-stat in the YFZ.

Yer way too lean on the main dude, stock is a 158. Infact yer probably lean everywhere if you havent thrown in a richer needle yet. An extremely lean bike will idle really erratic too.

With a slip-on and even the stock airbox (lid off) you should be up around 45 or 48 on the pilot......richen the stock needle (lower the clip) or a NCVQ (YZF) needle in the middle.......and at a minimun a 162 or 165 main jet.

Promise those specs will work .......pending your carb isnt faulty.

Make sure youre using genuine Kehien jets and not those cheezy Dynajet jets.

I have a dr.d slip on with a 172 MJ and a 45 idle. Gytr needle too and mix screw out 2. Perfect. When I am running hard the head pipe just glows a little..maybe an inch or two from the head. If I idle for a while it gets hotter. Also running a K&N.

When it was all stock it ran much leaner. I could run it 100 yards up and down the street and I would get almost 6 inches of glowing head pipe everytime. In the dunes it just glowed bright.

a 155 is way lean...even for stock as mentioned above.

Wow, a lot of mis-information here.....

The YFZ450 is known to run very hot at the head pipe. A glowing head pipe for the first 6-8 inches in normal at NIGHT. If its glowing during the day, you are too lean.

Now Dano, youu said int he first post that your head pipe was NOT glowing, is that correct?

Besides that, on the YFZ with what you have described I would put the following in your bike, 168 main, 42 pilot, NCVQ needle on the 3rd clip down from the top. Tthe 155 is too lean for a stock set-up.
What intake did youu have on it before?

Diesel, that damn stock pilot (42) made my bike pop on decel like a mofo....and I dont like backing the fuel screw out that far just to compensate. The effer felt like it was going to fall out.

And yes....stainless steel head pipes glow at night

Yeah, the 42 is a pain sometimes. Phil has a good point, 45 pilot may be a better option. Point is your going to have to play with it.

i don't know why people don't listen or believe me.

I hear ya! when you actually know something, you become invisible.

No chit? I guess they just use the temp sensor and fan to keep things in check. I did my bro in-laws YFZ, and used a complete Sparks Racing kit. They supplied the pipe, jetting and intake kit and I did the cam mod for him. His quad freakin hauls azz, and there is no glow on the pipe.

Glow is normal the new 4 strokes run best leaner and hotter to a point.the stock yfz glows big time!

I think everyone agrees a stock quad would to this. They have to be pretty damm lean to get a green sticker. And lean makes exh. temps quite hot.

But once you've modified things such as pipes, intakes and jetting, there should be no way you would want it that lean! a/f on a performance build should be around 12 to 13:1. Stock would have to be well above 14:1 to earn a green sticker in CA.

There is some basic info on all this right here: http://en.wikipedia.org/wiki/A/f_ratio

yeah you guys, the answer is right here, bunch a dummy heads

That sounds like sumphin my kids would say!!!