Carb Jetting EXPERTS... am I so close......but..

[Guest]

Okay, long story short..... 82 GS1100E old yosh 4-1

Using the Carb Jetting Method as scene on the site I've been working from top circuit to bottom

Main was too rich so I went from a 122.5 to a 117 - Bike NOW pulls nice from 7-9K

Dynajet needle - Needle was set in the middle (third from bottom) notch but still seemed a tad bit sluggish from 5-7k. **NOTE: I had Duaneage ride the bike in front of me, and (ONLY ONCE) I noted when he flogged it in probably 3rd gear a puff of black smoke from the exhaust. He seemed to think it was a tad to rich in the needle. ** ANOTHER NOTE: with these setting, everything in the pilot circuit felt smooth and plugs looked ok.

So... I raised the needle clip to the the forth notch from the bottom, thus leaning out the needle. Bike pulls nice and hard in the mid range now... obviously.

However, I am now getting what seems to be a flat spot ( not surging though) from 2-3.5k on 1/8 throttle (full throttle pulls right through).. and popping. I initally had my screws at 2.5 out when feeling this. My crappy logic told me that since I leaned everything out on the higher cicruits, that I should probably richen the mixture... so I went to 4 turns out. Doesn't to have seemed to help. So now I am thinking maybe I should be leaning it out from 2.5 turns, since the flat spot really feels like it's rich symptom. FYI my pilot jet is 45 which is stock. ... I'm really hoping to sort this out with the mixture screws. Am I way off here? Could the popping and flat spot be a smyptom of richness?

[TheCafeKid]

Okay, long story short..... 82 GS1100E old yosh 4-1

Using the Carb Jetting Method as scene on the site I've been working from top circuit to bottom

Main was too rich so I went from a 122.5 to a 117 - Bike NOW pulls nice from 7-9K

Dynajet needle - Needle was set in the middle (third from bottom) notch but still seemed a tad bit sluggish from 5-7k. **NOTE: I had Duaneage ride the bike in front of me, and (ONLY ONCE) I noted when he flogged it in probably 3rd gear a puff of black smoke from the exhaust. He seemed to think it was a tad to rich in the needle. ** ANOTHER NOTE: with these setting, everything in the pilot circuit felt smooth and plugs looked ok.

So... I raised the needle clip to the the forth notch from the bottom, thus leaning out the needle. Bike pulls nice and hard in the mid range now... obviously.

However, I am now getting what seems to be a flat spot ( not surging though) from 2-3.5k on 1/8 throttle (full throttle pulls right through).. and popping. I initally had my screws at 2.5 out when feeling this. My crappy logic told me that since I leaned everything out on the higher cicruits, that I should probably richen the mixture... so I went to 4 turns out. Doesn't to have seemed to help. So now I am thinking maybe I should be leaning it out from 2.5 turns, since the flat spot really feels like it's rich symptom. FYI my pilot jet is 45 which is stock. ... I'm really hoping to sort this out with the mixture screws. Am I way off here? Could the popping and flat spot be a smyptom of richness?

I will post this disclaimer right off the bat lest anyone choose to berate me for my offering of "bad information"

I AM NOT A CARB GURU

With that out of the way, I am going to tell you what SEEMS to have worked on MY BIKE. And, ind doing so I will tell you how I tried to analyze MY symptoms...My bike is not perfect, but I think its as close as I can get without paying for time on a Dyno, or breaking out a exhaust gas analyzer or any of that crap. Seat of the pants feel, plug reads and basic driveability are what I used to assess if what I had was where i needed to be.

I assume that youre running pod filters? or no? If you're running the STOCK airbox, you basicly need what Dynojet refers to as the Stage1-2 kit. I am not possitive but I think they suggest using the DJ114 main with the use of a high flow aftermarket pipe. Dunno what that translates to in Mikuni measurements, but I am thinking that your prolly still a hair rich on the main. Dunno for sure...AT ANY RATE, heres my set up:

With the 83 1100E/ES
KN Pods
SuperTrapp header/can combo 7 discs installed
Dynojet Stage 3
138 main
needle in the 4th clip from bottom
stock 45 pilot, screws 3.5 turns out (this may still be a hair rich, but it got rid of the popping, so im sticking with it for now)
180 air correction jet ( I did not install the DJ air correction, and this may help my popping and allow me to back off the adjustment screw some, but it will wait till i return from my trip)

Let me ask:

Your "flat spot" : Worse or better or same when the bike warms up? This little test alone is what basicly "shown me the ligghhht" on diagnosing my problems, and then chosing my course of action. If the problem is WORSE when the bike warms, its too rich. If it gets better as the bike warms up, its too lean. If it stays the same, you have a problem somewhere other than the pilot circuit IMO.
Having said that, there is a definite trade off when running the pods and pipe combo. Some "flat spots" are simply just hard to tune out of the bike, and you may find it easier to live with it than drive yourself nuts trying to tune it out. One thing *I* might suggest is that if you find the pilots having no effect on your current problem, stepping back DOWN on the needle to the 3 from bottom clip, adding the "dynojet spacer washer" and then perhaps even ANOTHER washer. 4 may be too lean, 3 and a single spacer to rich still. Perhaps another spacer will smooth it out more.

I am currently having an inner struggle with myself on clip possition setting. RIGHT NOW i have it at 3 plus spacer from bottom. Plugs are a *little* dark. Pretty close to the rich side of good, but still in the "dont F with it, its running nicely" stage. Since the bike is a daily rider, I prefer to keep IT happy, at the expense of a little bit of "holy crap that was fun" when cranking the throttle. 4th clip might actually be a tad lean, but lean is mean as they say, and that "Holy Crap" factor will be there. However, I am leaving for W Va on Friday morn. 4k feet higher in elevation than i am now. If im just a hair rich now, it could be sloggingly rich when i get there. So im gonna move em.

On the "popping cause your too rich" question:

Everything Ive EVER EVER been taught is that popping on decel is a LEAN condition. However, there are those that i know who have VERY VERY nice running bikes (not GSs, but its kissing cousin, the KZ) that do not pop who say that you actually can get popping thru the pipe, more of a single "pop..........Pop.....gurggle gurggle" if the pilot setting is TOO RICH. Their theory, and i suppose its plausible, is that with the pilot being so rich, unburnt gas is expelled into the header, where it can collect a bit. The temps at the head are pretty hot. Perhaps hot enough to combust gas vapor as the next stroke puts out some super heated air...I dunno.. Again, before I am harrassed, I am not an expert on the subject, but it DOES sound plausible. I guess the next question is: do you backfire thru the carbs at all? I have this problem currently. I have a short, single pop now and then thru the pipe..following by gurgling as the RPMS get low, and then every now and then a pop thru the carb, which is a sure sign of being too rich on the pilot. SOOOOooo Ima dial them back a half turn and see what happens. Honestly, the bike runs GREAT otherwise. Smooth at all RPMs, except down low, where it gets a little wet and rythmic, a sure sign of richness. But I tried the screws at 3 with the needles NOT at 3, and i got popping like a SOB on decel. However, I will see what happens now that ive richened the needle a bit...Its just annoying little " i dont like the way that sounds" tuning now, but the bike will straight go better than it ever has....

[maro]

okay, good stuff Josh.

and for what it's worth, in case there are those of you who want to flame broil josh on his carbs expertise, I sent Josh a PM to take a look at This thread as I know he was dealing with a similar issue in the past and he always gives a thoughtful response. so thanks!!

as for the bike in question. I have a stock airbox with a 4-1 pipe and home made baffle a la MR. Duaneage. We THINK.... it flows well, however, who the hell really knows.

When I had the bike on the 3rd notch, I personally thought it was pulling pretty well through all the RPM's. Seeing the black puff proved it was a bit too rich.... I'm just not sure where? Perhaps my Mains are still too big. Though i seem to pull through the 7-9k range just fine. Should I do actaully d plug chops on the main to find out for sure... probably...when I have a day to spare.

I can get at the needles easily and like the idea of bring the clip between the 3rd and 4th notch to see how that feels. I happen to have those fun raido shack washers so that's easy.

On my commute today I couldn't really feel a difference when warmed up on the bog in the pilot circuit. If I had to venture a guess....Seemed like it did it more when cold.

Rich or Lean... is a question a can't seem to figure out. I know that the tach needle hangs up at 2 / 3.5 unless I open the throttle.

[TheCafeKid]

okay, good stuff Josh.

and for what it's worth, in case there are those of you who want to flame broil josh on his carbs expertise, I sent Josh a PM to take a look at This thread as I know he was dealing with a similar issue in the past and he always gives a thoughtful response. so thanks!!

as for the bike in question. I have a stock airbox with a 4-1 pipe and home made baffle a la MR. Duaneage. We THINK.... it flows well, however, who the hell really knows.

When I had the bike on the 3rd notch, I personally thought it was pulling pretty well through all the RPM's. Seeing the black puff proved it was a bit too rich.... I'm just not sure where? Perhaps my Mains are still too big. Though i seem to pull through the 7-9k range just fine. Should I do actaully d plug chops on the main to find out for sure... probably...when I have a day to spare.

I can get at the needles easily and like the idea of bring the clip between the 3rd and 4th notch to see how that feels. I happen to have those fun raido shack washers so that's easy.

On my commute today I couldn't really feel a difference when warmed up on the bog in the pilot circuit. If I had to venture a guess....Seemed like it did it more when cold.

Rich or Lean... is a question a can't seem to figure out. I know that the tach needle hangs up at 2 / 3.5 unless I open the throttle.

If it felt like it did it more when cold, then its still lean somewhere. I would venture to guess its the main too rich, the needle too lean. Thats what was ORIGINALLY happening with my ES. The 135 main was simply too big. The bike had enough torque to slog thru the richness, the needle was set way lean to compensate for the overly rich main. Idealy, your main is set right when the bike will pull in second from 2k to redline with NO stumble or flatspots. The needle will come in to play more when you have the main correct. 7-9K is pretty much into the main, last of the needle. The 2.5/3.5 K stammers *I* thought would be in the pilot since you're only using a little over 1/8 throttle, but Ive found it more in the needle, and since ive played with that, it went away completely. Now it gets a little sloggy up top when its hot. So i think im simply half a clip too rich on the needle. I JUST got off the phone with Bill about this very thing, and, contrary to my understanding, I was STILL missing a washer over the needle as per his instructions. The Dynojet washer PLUS one washer is the way to go he said. I will give it a shot at clip three plus the DJ and another washer...

[maro]

If it felt like it did it more when cold, then its still lean somewhere. I would venture to guess its the main too rich, the needle too lean. Thats what was ORIGINALLY happening with my ES. The 135 main was simply too big. The bike had enough torque to slog thru the richness, the needle was set way lean to compensate for the overly rich main. Idealy, your main is set right when the bike will pull in second from 2k to redline with NO stumble or flatspots. The needle will come in to play more when you have the main correct. 7-9K is pretty much into the main, last of the needle. The 2.5/3.5 K stammers *I* thought would be in the pilot since you're only using a little over 1/8 throttle, but Ive found it more in the needle, and since ive played with that, it went away completely. Now it gets a little sloggy up top when its hot. So i think im simply half a clip too rich on the needle. I JUST got off the phone with Bill about this very thing, and, contrary to my understanding, I was STILL missing a washer over the needle as per his instructions. The Dynojet washer PLUS one washer is the way to go he said. I will give it a shot at clip three plus the DJ and another washer...

Well, I'm thinking you might be right about the main being a bit too big still... for me, as what you stated seems to make sence in that the lean needle is compensating for the rich main. I don't have smaller mains on order so for now . . . I will try ..well... the same exact thing you are doing... except I will step one washer down from the 4th notch from the bottom. So I will be at 3.5 notches from the bottom

MAN, it's ridiculous how just these miniscule adjustments make all the difference. Phew.

[TheCafeKid]

Well, I'm thinking you might be right about the main being a bit too big still... for me, as what you stated seems to make sence in that the lean needle is compensating for the rich main. I don't have smaller mains on order so for now . . . I will try ..well... the same exact thing you are doing... except I will step one washer down from the 4th notch from the bottom. So I will be at 3.5 notches from the bottom

MAN, it's ridiculous how just these miniscule adjustments make all the difference. Phew.

Hey before you go ordering new mains, if you have DJ needles, I can send you two sets of mains from a DJ kit that I ordered. I used the stage three so the stage one and two jets are still there. Id like em back eventually, but they may help you decide which works best, then you can do the Mikuni translation and order. No sense in throwing money at it unless you know its gonna work..

It is pretty amazing. Whats more amazing is that before you got close, there was just SO much wrong, you wouldnt have been able to decifer this little annoying stuff. But once i was really damn close, and then pretty much there, all that little stuff really sticks out. You're trying to squeeze that last one or two tenths out of an otherwise great running set up...it can be maddening. Like Ive said, if i had an airbox, I would ditch the pods and go with it, because I can tell the difference when the weather/temp changes.. I just choose to accept it, and not obbsess about trying to tune it out, because its not going to happen.

[maro]

Thanks for the offer Josh. Better yet, what size are the DJ mains you have? Mains are only a couple bucks from z-1 and i don't mind having extras. I can do the translation now and just order a couple sets.

[TheCafeKid]

I do believe the Stage 1-2 kit starts DJ110 and DJ114...

[maro]

uh huh...now I have to find the translation. I currently have oem 117s in??

[maro]

found it

I think the conversion is Dynojet X .9375 = Mikuni

[maro]

okay, this is curious.. here is stock setting:
1982 1100 EZ

Specs in mm.
Carb Type- Mikuni BS34SS
Bore Size-34 mm
ID# - 49220
Idle r/min - 1050 +/- 100 r/min
Fuel Level - 5.0 +/- 0.5
Float Height - 22.4 +/- 1.0
Main Jet - #110
Main Air Jet - 1.2
Jet Needle - 5D58
Needle Jet - X-1
Pilot Jet - #45
Bypass - 0.8, 0.8, 0.8
Pilot Outlet - 0.9
Valve Seat - 2.0
Starter Jet - #32.5
Pilot Screw - Pre-Set, Varies
Pilot Air Jet - #170
Throttle Cable Play - 0.5-1.0
Choke Cable Play - 0.5-1.0


So, wouldn't I want my main jet a bit larger since I have the 4-1?

because if you Times (x) the DJ114 by .9375 you get roughly 106?

[TheCafeKid]

okay, this is curious.. here is stock setting:
1982 1100 EZ

Specs in mm.
Carb Type- Mikuni BS34SS
Bore Size-34 mm
ID# - 49220
Idle r/min - 1050 +/- 100 r/min
Fuel Level - 5.0 +/- 0.5
Float Height - 22.4 +/- 1.0
Main Jet - #110
Main Air Jet - 1.2
Jet Needle - 5D58
Needle Jet - X-1
Pilot Jet - #45
Bypass - 0.8, 0.8, 0.8
Pilot Outlet - 0.9
Valve Seat - 2.0
Starter Jet - #32.5
Pilot Screw - Pre-Set, Varies
Pilot Air Jet - #170
Throttle Cable Play - 0.5-1.0
Choke Cable Play - 0.5-1.0


So, wouldn't I want my main jet a bit larger since I have the 4-1?

because if you Times (x) the DJ114 by .9375 you get roughly 106?

Not necessarily. The tapper of the dynojet needles allow for more fuel into the midrange at a faster rate. In MANY DJ set ups, you are actually clamping DOWN on the jetting. For instance, ive been told that with a certain GSXR kit, you are given reducer plugs for the slide holes, and a SMALLER than stock main jet. Thats another thing..did you, or is it adviseable to drill the slides with the stage one or two set up? Id have to read the instructions from DJ, i didnt really pay attention to them. I will give them a look tonight when i get home and get back with you on THAT. Perhaps they suggest a larger than 114 as well. Actually I seem to remember them suggesting that if you have a HIGH FLOW pipe (read: no baffle i would assume) to use the stage three kit on the bike even without the pods.. I will double check bro and let you know for sure. i dont want to give you any for real bad info and then have you chasing your tail...

[maro]

Not necessarily. The tapper of the dynojet needles allow for more fuel into the midrange at a faster rate. In MANY DJ set ups, you are actually clamping DOWN on the jetting. For instance, ive been told that with a certain GSXR kit, you are given reducer plugs for the slide holes, and a SMALLER than stock main jet. Thats another thing..did you, or is it adviseable to drill the slides with the stage one or two set up? Id have to read the instructions from DJ, i didnt really pay attention to them. I will give them a look tonight when i get home and get back with you on THAT. Perhaps they suggest a larger than 114 as well. Actually I seem to remember them suggesting that if you have a HIGH FLOW pipe (read: no baffle i would assume) to use the stage three kit on the bike even without the pods.. I will double check bro and let you know for sure. i dont want to give you any for real bad info and then have you chasing your tail...

Cool! thanks. I have a feeling I will be calling Chef tonight at some point as he knows these carbs better than me since I bought them jetted from him!

Finally, and just to open up a can of worms, I wonder if tinkering with the baffle, aka, allowing more airflow would change some thing? hmmm