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Discussion Starter #1
what would happen if you went one tooth to far when you retard the cam, Would it actually break some thing or would it just not run right. I have done the cam mod have a K&N no lid, FMF slip on and Yamaha can't get the needle to tune in, it runs fine top and bottom but mid range won't tune no matter what the clip position is. can any one help.
 

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I believe you are mistaken Max-action. The idle is responsible for idle and just off idle, the pilot works up to about 1/4 throttle, then the needle and to a lesser degree the main, from 3/4 on it is the main. If you are good on top and bottom it is most likely your needle.
 

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Discussion Starter #5
So why won't the thing dial in on the needle no matter what position the clip is in. :angry :disgust :bawl
 

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Also, I have never heard anything good about the dyno jet kits w/the YFZ. Do a search and you'll see what I mean.
 

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I believe the YZ needle comes in the GYTR kit. I have also heard good things about the James Dean kits. A lot of people are ditching the Dyno kits for the JDs
 

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I had the Dyno Jet kit and it is so much easier to jet this thing once you trash everything that came with the kit and go to the store and pick up the YZ needle and some jets. In the long run you will be much happier.
 

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48 pilot - $1.99 from my yami dealer
170 pilot - $3.99 from the dealer
YZ450f needle - $19.99 from dealer







Or





Dyno jet kit - $65.00





I'd rather buy it piece by piece. Plus it is good to carry spare jets in various sizes. I'd get a ziptye screw for the fuel mixture screw. That way you don't have to turn the carb sideways everytime you want to adjust the mixture. That is my only w00ter an=bout the FCR carb. But it's easily fixed.
 

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Originally posted by YFZ439@Dec 31 2003, 11:47 AM
I believe you are mistaken Max-action. The idle is responsible for idle and just off idle, the pilot works up to about 1/4 throttle, then the needle and to a lesser degree the main, from 3/4 on it is the main. If you are good on top and bottom it is most likely your needle.
:stupid
 

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Originally posted by cjpoole1+Dec 31 2003, 11:19 AM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (cjpoole1 @ Dec 31 2003, 11:19 AM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin--YFZ439@Dec 31 2003, 11:47 AM
I believe you are mistaken Max-action.  The idle is responsible for idle and just off idle, the pilot works up to about 1/4 throttle, then the needle and to a lesser degree the main, from 3/4 on it is the main.  If you are good on top and bottom it is most likely your needle.
:stupid [/b][/quote]
my bad...

here is some better information:

Main fuel jet:

The proper main fuel jet will give best full throttle performance, but also affects mixture as far down as 1/8 throttle. I know you don't believe this second part, because I didn't believe it until I saw it happen while tuning an extensively instrumented test engine. Suspend your beliefs about the main fuel jet only affecting mixture when the slide is all the way up & the needle is all the way out of the needle jet and think for a minute. The main fuel and air jets feed the emulsion tube which feeds the needle jet and jet needle. When a more fuel rich emulsion is bled past the same restriction (needle jet area minus jet needle area), the engine gets more fuel. You must select the full throttle jetting first. If you go and find a needle that works with the wrong main jets, it won't work with the right ones, and you'll have to go through the needle selection process all over again when the main jets are correct. Trust me


Needle selection:

1st letter: This portion of the needle controls mixture between approximately 1/3 and full throttle. If the engine fails to respond to main jet changes, you may be too lean on this, causing the tip of the needle to be very large. This would tend to artificially limit fuel flow at full throttle, taking control of WOT fuel delivery away from the main jet. Selecting this is much easier than many believe. If you find that mixture is good at 1/4 throttle, but too rich at 3/4, you probably have a needle with too great a taper angle. If the mixture is good at 1/4 throttle, but too lean at 3/4, you probably have a needle with too small a taper angle. I know you went and made sure the main jets were sorted out before testing the needle taper, right?

2nd letter: This generally doesn't need to be played with much. If, when adjusting the clip, you find that you are at the 1st groove and still need to start the taper later, you may need to select a needle with a longer L1 dimension. If you find yourself at the 7th groove and needing to start the taper earlier, you may need to select a needle with a shorter L1 dimension.

3rd letter: This portion of the needle has the greatest effect on mixture between closed and 1/4 throttle. If the engine is too rich while gradually accelerating through 1/8 throttle, select a needle with a larger root diameter. If the engine is too lean when gradually accelerating through 1/8 throttle, select a needle with a smaller root diameter. You will drive yourself completely batty trying to sort out this if the slow fuel and air jets aren't right. Conversely, you will drive yourself completely batty if you try to sort out the slow fuel and air jets if the needle root diameter isn't right. So you're pretty much screwed either way here. And if you didn't set the float level to 9mm, just go jump off a cliff right now and get it over with because that will have a fairly large effect on how much fuel spurts up through the needle jet when the slide's only open a little bit.

Clip position: This controls mixture between approximately 1/8 to 7/8 throttle. Higher clip position for leaner, lower for richer. Unlike taper, this setting will change mixture (approximately) evenly throughout the throttle position range, with a slight tendency to affect the lesser throttle positions more than greater. You should work to find a needle which allows you to run the clip on the 3rd, 4th (middle), or 5th position. If you find that mixture at 1/3 through 3/4 throttle is too lean, raise the needle!
_________________
 

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Hey, I had the dyno jet kit, and had the same problem. Its junk, and you'll never get it to run right. I returned mine and did what many others did, and piece a kit together. I ended up running 175, 48, yz needle (same as gytr for yfz) on the 4th pos., and 2 turns out on mixture screw. I also highly recomend the zip ty mixture screw.
 

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Nice post Maxx Action
:rock
 

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:disgust Hey I did the cam mod today. And now the bike is hard to start! I saw a pic of the 3 jets in the carb somewhere
on this site. main jet, pilot jet, starter jet. was wondering if I need to change the starter jet. Now I have a 180 main, stock
clip set in middle, 142 pilot, zip ty 1.5 turns out! HELP
 

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ummmm, well if you mess with the starter jet, make sure you go up, not down liek I did. I was having big problems with cold starts on the yz exhaust cam, and tried everything, including changing the starter jet. Going down never solved anything. THe reason I initially went down, was because I would end up flooding the poor bike out cause it would take soooooo long to start. But yeah, that didnt work. Maybe try going up?
I have since done the cam mod (instead of the yz cam) and have had no problems. While it still doesnt start the same as with the stock exhaust cam, with stock timing, it still is firing up under 10 turnovers, which is pelnt fine with me. So, as far as having hard starting on the cam mod, I don't know what to tell you. Most people dont have a problem. Most people also dont have a problem with the yz exhaust cam, BUT I SURE THE HELL DID! ha ha. Good luck man, if you cant think of anything else, I would try the starter jet. Maybe a 100, or 110. I would double check the install though, I have heard of people accidentally changing the timing on the intake and exhaust being off as well, and not even realizing it.
 
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