First Ride 06 YZ450 POP POP POP

I always replace the phillips head float bowl screws with allen heads.

It makes it much easier to change jets.

Of course you know Yamaha took care of that on the 06. It's about time they got rid of those strip-out specials!

Mine also popped on decel brand new, so I raised the pilot jet one size, installed a ziptie air screw adjuster, and a Boyesen quickshot. Now no popping and accelleration better(it was great before).

Entire job was less than an hour, and most of that was removing the engine bracing above the carb.

Man I love this bike...................

Did that work for you (the pilot jet change? I just bought an 06 and live here in Phoenix as well. The bike popped like crazy on decel. It also seems to stumble at 1/4 throttle openings, sounds like it gasps for air occasionally, or a mur mur sound ( dont know the technical term for it). It seems to be ok under hard acceleration. I messed with the fuel screw and it seemed to help somewhat, but not completely happy with it, have an 03 that runs better with same jetting as 06. Any ideas anybody?

Rode this weekend after changing the pilot to a 48 and the main to a 170. Still pops on decel, but is much better than with the stock 42 pilot. Still had to turn fuel screw out 5 turns to get it to pop only occasionally. Noticed some drool from silencer. Guessing this is too rich on the pilot circuit. Will tamper with the needle jet clip and change to it to the 5th position. Read a thread that recommended 5th and another thread recommends changing the needle to a NCYR with the clip in the 2nd position. :thumbsup:

Rode this weekend after changing the pilot to a 48 and the main to a 170. Still pops on decel, but is much better than with the stock 42 pilot. Still had to turn fuel screw out 5 turns to get it to pop only occasionally. Noticed some drool from silencer. Guessing this is too rich on the pilot circuit. Will tamper with the needle jet clip and change to it to the 5th position. Read a thread that recommended 5th and another thread recommends changing the needle to a NCYR with the clip in the 2nd position. :lol:

How did this work out for you?

What would be the benefit of the Boyesen AP cover? I have the AP mod done to mine do I need the cover also?

Yeah, I'm having the same problem. Am thinking of doing the AP mod. dj, it sounds like th AP mod didn't resolve the issue for you?

Yeah, I'm having the same problem. Am thinking of doing the AP mod. dj, it sounds like th AP mod didn't resolve the issue for you?

Im not really having any issues. I was just wondering what the Boyesen AP cover does. I am still going to jet it this weekend and see how it works out.

Yeah, I'm having the same problem. Am thinking of doing the AP mod. dj, it sounds like th AP mod didn't resolve the issue for you?

there is a ton of info on this fix...your jetting needs to be replaced and you must add a adj fuel screw to resolve...on the 06

45/48 pj - to start

165-170mj

NFLR needle jet

2 turns out on the screw

AP mod is better than Quickshot -

http://jdjetting.server304.com/xcart/product.php?productid=49&cat=0&page=1&featured

there is a ton of info on this fix...your jetting needs to be replaced and you must add a adj fuel screw to resolve...on the 06

45/48 pj - to start

165-170mj

NFLR needle jet

2 turns out on the screw

AP mod is better than Quickshot -

http://jdjetting.server304.com/xcart/product.php?productid=49&cat=0&page=1&featured

Yes, I've been reseaching a ton on jetting and AP mod. Sorry, I should have quoted Sean before replying before. I switched to 48/170 NFLR needle 4th position and 2 turns out on the zipty screw yesterday and that's when my trouble began (and improved actually). The popping got much better but now it's stumbling/surging/missing at 1/4-1/2 throttle with a steady throttle. I'm thinking of doing the AP mod which is why I asked dj why he felt the need for the cover as well. Good to know the AP mod is better then quickshot. I just need to figure out where to get leak jets down here in Mexico.

The popping got much better but now it's stumbling/surging/missing at 1/4-1/2 throttle with a steady throttle.
The NFLR is roughly a half step leaner than the stock needle. If the bike were mine, I would lower the needle one spot to see if the problem gets better or worse. Normally, too lean will cause an irregular, surging misfire, whereas too rich will cause a regular stutter, as though the engine were firing on every second power-stroke. In borderline cases of either, it can be hard to tell.

IMO, far too much worry is expended over popping on deceleration. If mine doesn't do it at all, I usually take it as a sign of it being too rich, and turn the fuel screw in 1/4. Some engines are more prone to this than others, and YZF's are one of them. It isn't a problem unless it's loud and fairly constant.

Also, any time you are troubleshooting decel backfire, be sure to inspect the exhaust for air leaks first. If you try to cure a leaky exhaust by rejetting your carb, your bike will run badly and pop, both.

http://www.thumpertalk.com/forum/showthread.php?p=3710599#post3710599

The NFLR is roughly a half step richer than the stock needle. If the bike were mine, I would lower the needle one spot to see if the problem gets better or worse. Normally, too lean will cause an irregular, surging misfire, whereas too rich will cause a regular stutter, as though the engine were firing on every second power-stroke. In borderline cases of either, it can be hard to tell.

IMO, far too much worry is expended over popping on deceleration. If mine doesn't do it at all, I usually take it as a sign of it being too rich, and turn the fuel screw in 1/4. Some engines are more prone to this than others, and YZF's are one of them. It isn't a problem unless it's loud and fairly constant.

Also, any time you are troubleshooting decel backfire, be sure to inspect the exhaust for air leaks first. If you try to cure a leaky exhaust by rejetting your carb, your bike will run badly and pop, both.

http://www.thumpertalk.com/forum/showthread.php?p=3710599#post3710599

I was hoping you'd chime in.:lol: When you say lower the needle I'm assuming you mean raise the clip to the 3rd position from the top so that the needle drops down lower making for a leaner setting. Or did you mean lower the clip position to 5th thus raising the needle? I'm assuming the 1st since the NFLR is richer then stock and issue happened when I went richer jetting.

You could do either and note the improvement or lack of it, but I was suggesting that you lower the needle, which you would in fact do by raising the clip.

Also note that I should have said that the NFLR-4 is a half step LEANER than the standard NFPR-4, and not the other way around. Since that is the case, it might be more prudent to try raising it first, but as long as moving it makes a difference, it will help you track it down.

You could do either and note the improvement or lack of it, but I was suggesting that you lower the needle, which you would in fact do by raising the clip.

Also note that I should have said that the NFLR-4 is a half step LEANER than the standard NFPR-4, and not the other way around. Since that is the case, it might be more prudent to try raising it first, but as long as moving it makes a difference, it will help you track it down.

The way the manual words it is confusing as I thought it meant what you originally said that the NFLR is a half step richer then the NFPR. Before I mess with the jets I've got to adjust my front brake as it caused my first little slam on the new bike. After a 45 table there is a tight left turn so you have to brake fairly quickly. I barely grabbed the front brake, locked it up and was down before I had any time to react. :lol: Man is the front brake tight! Well, I think my bike is officially broken in as I now have 3 hours on it and one crash.

I'll play with the needle clip as soon as I can put weight on my left thigh and ride again. That and the AP mod to stop the bog and this bike should be dialed. I already love the suspension (compared to my WR) and it's not even broken in yet.

Yes, I've been reseaching a ton on jetting and AP mod. Sorry, I should have quoted Sean before replying before. I switched to 48/170 NFLR needle 4th position and 2 turns out on the zipty screw yesterday and that's when my trouble began (and improved actually). The popping got much better but now it's stumbling/surging/missing at 1/4-1/2 throttle with a steady throttle. I'm thinking of doing the AP mod which is why I asked dj why he felt the need for the cover as well. Good to know the AP mod is better then quickshot. I just need to figure out where to get leak jets down here in Mexico.

I was wondering what the difference was between the two and I guess if you have one you don't need the other. I figured that out today.

Guys, as far as the AP mod vs. the QS goes, nothing is going to perform better than tried and true tuning, and that is what the AP mod is. I honestly can't tell you what the QS actually does or is meant to do, but it most certainly is not going to out perform proper tuning of the AP circuit which comes by way of AP timing adjustments, leak jet tuning for proper AP volume and an increase in AP squirt response from directly connecting the AP linkage.

The NFLR is roughly a half step leaner than the stock needle. If the bike were mine, I would lower the needle one spot to see if the problem gets better or worse. Normally, too lean will cause an irregular, surging misfire, whereas too rich will cause a regular stutter, as though the engine were firing on every second power-stroke. In borderline cases of either, it can be hard to tell.

IMO, far too much worry is expended over popping on deceleration. If mine doesn't do it at all, I usually take it as a sign of it being too rich, and turn the fuel screw in 1/4. Some engines are more prone to this than others, and YZF's are one of them. It isn't a problem unless it's loud and fairly constant.

Also, any time you are troubleshooting decel backfire, be sure to inspect the exhaust for air leaks first. If you try to cure a leaky exhaust by rejetting your carb, your bike will run badly and pop, both.

http://www.thumpertalk.com/forum/showthread.php?p=3710599#post3710599

I first tried raising clip position to 3 and then tried it on 5 and neither one is any better then 4th position in regards to the missing from 1/4-3/4 throttle. Any other suggestions to fix this hesitation? It's not as bad when I'm on the gas real hard because it seems to move through the misses quicker but when I slowly roll on the throttle or hold anywhere from 1/4-3/4 throttle it misses. Again, I'm running 48/170 NFLR 4th clip (tried 3 and 5) and Zipty FMS at 2 out (tried from 0 to 4 and the only thing that changes is the popping on decel). Should I try a 168 or 165 main? Is humidity coming in to play. Weather is anywhere from 65-80 depending upon the day and high 60-90humidity.

Thanks!

I first tried raising clip position to 3 and then tried it on 5 and neither one is any better then 4th position in regards to the missing from 1/4-3/4 throttle. Any other suggestions to fix this hesitation? It's not as bad when I'm on the gas real hard because it seems to move through the misses quicker but when I slowly roll on the throttle or hold anywhere from 1/4-3/4 throttle it misses. Again, I'm running 48/170 NFLR 4th clip (tried 3 and 5) and Zipty FMS at 2 out (tried from 0 to 4 and the only thing that changes is the popping on decel). Should I try a 168 or 165 main? Is humidity coming in to play. Weather is anywhere from 65-80 depending upon the day and high 60-90humidity.

Thanks!

These bikes aren't meant to cruise along at a steady throttle position. Every MX bike that I've ever ridden has missed when held at a steady throttle position. Run it an' gun it Dude!

That's good to know. My WR450 never had this issue so I was assuming something was not dialed in with the jetting. I didn't realize the engines/carbs were that different. Regardless, I plan on going down to just the YZ450 and will be doing a lot of trail riding so it is a little bit of bummer if there is no fix for it. So there is nothing else jetting wise I should try like different main jet size? Maybe I'll just have to get used to it.

That's good to know. My WR450 never had this issue so I was assuming something was not dialed in with the jetting. I didn't realize the engines/carbs were that different. Regardless, I plan on going down to just the YZ450 and will be doing a lot of trail riding so it is a little bit of bummer if there is no fix for it. So there is nothing else jetting wise I should try like different main jet size? Maybe I'll just have to get used to it.

Did you ever try a 45 pilot?

No, I jumped right from the stock 42 up to the 48 and it really fixed the pop on decel. Should I? I'm not afraid to experiement a little it's just that I really don't know what jet is affecting what issue so I want to have an idea before randomly swapping things out. So far the popping on decel is fixed and throttle response is pretty good (even though I'd like to try the AP mod once I can get my hands on a 70 leak jet) and the NFLR needle didn't seem any better at 3 or 5 so I'm going to put it back to 4th clip. The reason for my posts is because I'd like to get educated on what else might be causing the missing so that I can change that as well when I go back to the 4th clip position on the needle. So would it more likely be too rich on the main jet (maybe I could try a 168 or 165) or like you suggested the pilot (in which case I'd drop in a 45) or is it like Baron suggested that I really can't get rid of it and I should just leave it and ride?

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