More Airflow / More Popping

[lshafer]

Good morning everyone.

 

I've made a couple of changes to my 06 RSTD. I installed a set of RK exhaust that are drilled out on both ends (see through) and a set of K&N filters. After the installation of RK exhaust I started experiencing popping on decel when going from 4th down to 3rd and 3rd down to 2nd. After I installed the filters the exhaust seems a bit louder (the sound is perfect - not too loud but it sounds really nice on accelleration) and the popping does too. So, now that I've made those enhancements I want to rejet with bigger jets. My questions are:

 

1. Where and what jets should I buy?

2. Would rejetting take care of my popping issue?

3. Is there a step-by-step somewhere so I can do the install myself or would I be better off to take it to my Stealer considering my mechanical abilities are less that perfect?

 

I've already stuck more money into the bike than I wanted too this year so any do-it-myself work would be acceptable. I just don't know if replacing the jets is something I should tackle.

 

Thoughts, feelings, comments everyone?

Thanks,

Les

[phertwo]

Have you plugged your AIS system?

[Squidley]

Do a carb sync before you do anything else, also check for any vacuum leaks, both in the AIS system and vacuum caps. Installing the K&N's and the pipes will not affect the jetting enough to notice.

[SilvrT]

Ever since I installed (and drilled out) my RK's, my bike pops and spits like crazy on decel ... I've gotten so used to it that I hardly notice it anymore. When I put the stock pipes back on the popping isn't noticeable or is non-existant. I figgure that with the RK's being drilled out, there isn't any back pressure ... it's almost like a straight-pipe.

 

The AIS has been plugged and carbs sync'd and no vac leaks that I know of.

[phertwo]

SilvrT, I also had the popping on decel, all the time.. It was usually pretty quite though, not enough to be annoying. But I just recently adjusted my pilot mixture screws to ~4 turns out and I am no longer hearing the popping. I don't know why, but its cured this minor issue. Check it out, maybe it might work for you too.

[lshafer]

My overall goal with these modifications was to open up the air flow a bit and rejet with larger jets to gain a little additional HP. I don't really want to plug anything if changing the jets will correct the problem. Does anyone believe that uping the size of the jets won't correct what I have going on now?

 

My understanding is that the bike is running to lean after opening up the air flow. Installing bigger jets would add more gas thus correcting the leaness, correct?

 

I hope I don't have this all 'wrapped around the axel'!!!

[SilvrT]

SilvrT, I also had the popping on decel, all the time.. It was usually pretty quite though, not enough to be annoying. But I just recently adjusted my pilot mixture screws to ~4 turns out and I am no longer hearing the popping. I don't know why, but its cured this minor issue. Check it out, maybe it might work for you too.

 

Thanks for that info ... carb work / pilot screw adjusting, etc will be part of my upcoming winter maintenance.

[Venturous Randy]

Popping on decel is usually related to an exhaust leak. What happens is under decel, oxygen is being introduced into the exhaust and causing the popping. I doubt re-jetting is going to make any difference on deceleration. Now adjusting your fuel mixture screws may make some difference, as Phertwo noted, because that technically impacts the idle circuit and that is what is happening when you are under deceleration.

RandyA

[sKiZo]

Popping is more unburned gas in the pipes than anything else. And for whatever reason (I'm thinking screwy linkage) #4 seems to do it the most.

 

I always had some burbling and popping on a hard decel, like coming off a freeway on a short ramp. Even the occasional backfire from hell - the one that makes you want to look for holes in buildings where your valve might have landed. Tried this that and the other. I was able to tune a lot of it out with adjusting the PMS, but the real cure for me was switching to iridium plugs. Those apparently do a better job of scavenging fuel in the cylinders so you don't have any leftovers getting to the pipes. No fuel, no boom, even if you do have minor air leaks. Try it - you'll like it!

[SilvrT]

Popping is more unburned gas in the pipes than anything else. And for whatever reason (I'm thinking screwy linkage) #4 seems to do it the most.

 

That being the case, one might think it's running too rich so leaning it out a bit would reduce the amount of unburned gas in the exhaust...??? yes/no ???

[Marcarl]

That being the case, one might think it's running too rich so leaning it out a bit would reduce the amount of unburned gas in the exhaust...??? yes/no ???

You would think,,,,,,,,but if the mixture in the cylinder is too lean, then the plug won't fire it so the unburnt mixture ends up in the exhaust, and the exhaust from a working cylinder fires it. Sounds kind of neat, but does very little for pushing the piston back down.

JMT

[GaryZ]

I have modified my Ninja with aftermarket headers, a jet kit, and SuperTrapp mufflers. I adjusted the jets for the best mid-to-high RPM performance and still had problems in the low-speed circuit. My carb tune research suggests that these changes produce a lean low-speed (sometimes called idle circuit) condition. The engine is moving lots more air and the low-speed circuit is still adding the same amount of fuel. This condition can produce some or all of these symptoms; popping during deceleration, surging at light throttle, uneven idle.

 

My fix was a combination of turning out the low-speed screws (1/2 turn) and removing discs from the SuperTrapps until the popping was minimum.

 

I suggest that you check for vacuum leaks, exhaust leaks, and the carb sync. Then open up the low-speed screws. You should initially turn the screws in and count the turns, make a note in your manual. Usually these screws are around 2 turns out. Turn the screws out 1/2 turn more than the stock setting and take a ride. Turning them out more is OK, but, not more than 4 total turns.

[lshafer]

I rode about 250 miles yesterday and noticed that during moderate acceleration I'm getting a backfire at the top end of my gear when I shift to the next. Any thoughts? It also seems like the popping on decel is getting louder and more frequent. Now I'm starting to worry that this may be damaging to something???... Any thoughts of encouragment would be great.

[GaryZ]

I rode about 250 miles yesterday and noticed that during moderate acceleration I'm getting a backfire at the top end of my gear when I shift to the next. Any thoughts? It also seems like the popping on decel is getting louder and more frequent. Now I'm starting to worry that this may be damaging to something???... Any thoughts of encouragment would be great.

 

Light throttle, less than 1/8th turn, is primarily the low speed circuit. Assuming everything else is right, it still seems like a lean low-speed circuit condition.

[lshafer]

First, I'd like to thank everyone for the responses. I went out today and adjusted the pilot mixture screws out 1/4 turn. It was easy to do because the little caps that everyone talks about being on them weren't there. (I found that odd because EVERYONE said they would be and I purchased the bike brandy new so I don't think anyone already removed them.) Anyway, I took it for about a 15 mile ride and once I figured it was good and warmed up I tried a heavy deceleration while downshifting. Minimal popping and backfiring compared to before. I'll leave things as they are for a while and take the bike on a couple long trips and see how things go. If I still have a bit I might try adjusting out another 1/4" but we'll see. For now, I think I'm happy with the results. I'll go from here.

 

Again, thank to everyone who gave me an opinion. I LOVE THIS SITE!!!

[waterbug]

I just put some barrons on my bike that I picked up and they have no baffles in them making them straight pipes. I get a lot of poping now even between shifts she will pop, I know she needs a carb sync bad but she does seem to have some more power now. I can tell a difference in gas milage and power with these pipes and even more when I run with my cut down windshield than my xxl clear view also.