Need help tuning the xs11

[flyingdakota]

Hey Ya'll!
Back on the road and working on my bike! Finally got time to mess with it and new plates, tags and insurance. But there is some carb issues I need help with. Been doing some research but I'd like to be sure to buy the right jets I need if you experts think I may need them.
I need to fix the jetting my XS1100F....I am running a 4 into 1 exhaust with individual K&N style filters for each carb. I just checked my main jets 150 (137.5 is standard) and my pilot jets are 42.5 (standard)...here is my issue....hard starting...runs fine until hot, then it pops and misses, and then doesn't idle well (have to adjust to over 1000 rpm) and gets hot fast! When accelerating and at about 6k when opening throttle it stutters...pipes are blue....I am going to check valve clearance and clean carbs thoroughly then of course sinc them. Should I put in a large pilot jet first and/or try opening the main jets too?
Thanks in advance!
Tim

[Bonz]

Idle speed should be around 1100 rpm, if it was lower than that you have already addressed one potential issue.

Now you have to tell us how many turns out your idle mixture screws are. Sounds like it's not getting enough fuel at idle.

The high rpm issue could be the pods are not flowing air correctly. If they have a raised lip inside of the rubber you need to Dremel that away so you have smooth airflow.

I am going against the flow here, however blue pipes can indicate rich. The mixture is unburned and continues to burn as it leaves the engine, creating extra heat the would not be there otherwise. That is why I believe so many of the V twins that have fueling devices with their new headers get blued pipes. They are shooting way too much fuel into the engine.

[donebysunday]

Idle speed should be around 1100 rpm, if it was lower than that you have already addressed one potential issue.

Now you have to tell us how many turns out your idle mixture screws are. Sounds like it's not getting enough fuel at idle.

The high rpm issue could be the pods are not flowing air correctly. If they have a raised lip inside of the rubber you need to Dremel that away so you have smooth airflow.

I am going against the flow here, however blue pipes can indicate rich. The mixture is unburned and continues to burn as it leaves the engine, creating extra heat the would not be there otherwise. That is why I believe so many of the V twins that have fueling devices with their new headers get blued pipes. They are shooting way too much fuel into the engine.

+1 I think it was Blaine many many years ago that said the pipes (single wall, like Mac) are going to change color. Slight straw/gold indicates head pipe temp up to 600° blue was 600° + , purple 800° + .
Don't know if I remember exact but gold to blue was OK and purple dang HOT .
Now that we have our new, heat guns/temp indicator all we need is some scrap metal and a torch to see what temp is what color ?
I do not have a torch, yet.

[skids]

I agree with Howard. You can make the pipes blue (or black) with a mixture that is too rich. Question: does the muffler have a descent baffle? It needs one. I can say that the Jardine 4-1 exhaust will turn the headpipes either blue or gold. You add in the individual intake filters and you can have a leaner mixture. I have a 78E with Jardines and K&N indi filters. I had to play with it for a long time changing out the mains. I think the 150 mains made it "burble" when I goosed it from say 3500 rpms. I played with it until I got the best results with 142.5 mains (I think). The lower number mains would not accelerate beyond certain rpms. I live with a compromise because the ones that I have reach a maximum speed of 97mph. I live at 8800 feet elevation. I believe that I could probable raise the fuel levels to help that out. You need to realize that you should work with the mains first, then dial-in the pilot circuit.

I can also tell you that every time I messed with the midrange (78 and 79) by changing the clip position on the main needle, I ended-up beating my head against the wall. Whether or not you need to change the pilot jets from standard depends on the number of turns out from the lightly seated position. If you are more than 3 turns out, you need to reduce the pilot jet number. If you are 1/4 turns out or less, you might consider increasing the pilot number. The thing about that, I have seen differences due to aftermarket pilot springs... I had a set where the spring was thicker and shorter free length, and I wonder if the spring applied any compressive force at all when the pilot screw was 3 turns out.

Everything above depends on properly functioning (clean with proper micuni jets and parts), and a properly functioning exhaust system.

[motoman]

Torch and scrap metal will be of no indicator, as the head pipes are of a higher carbon steel than the scrap metal,.... and just use the torch for its intended use.....problem solved. BTW, metallurgy and certified welder was one of my many professions.

[Bonz]

I would ask what is the coloration of the spark plugs? Do they show lean, normal or do they show rich? Your plug the condition is the first and foremost and only predictable way to know the internal condition of your engine as combustion takes place. Using header pipes is about as good as seeing a dentist for an ingrown toenail.

Can you tell us if your pods have a rubber lip in them? If they do, it is impeding airflow and you are running rich.

What Skids said is spot-on for order of operations in tuning carbs. Mains first, then needle clip position and pilots/fuel screw setting. If you get the first two correct, there's no reason stock pilots will not handle fuel needs at idle or light cruise, IMO. Also in my experience float height simply richens or leans things when you give heavy throttle application by virtue of how far the fuel sits away from the main jet hole and the time it takes to get sucked up into it.

And to be more clear on my part, the double wall stock headers probably aren't going to show much discoloration if any. It's going to be on the single walled after market systems like your Mac.

My opinion on the headers turning blue because of a rich condition comes from a friend who is a powder coater and metal fabricator here in Colorado Springs. He high temp ceramic powder coated the black Holeshot header system I used to run on my ZRX 1200.

I asked him if header temps can get too hot for just a high temp ceramic coating and not the super high temp stuff some guys talk about doing. He said the only reason that would happen is if the bike is running rich because that's what causes excessive heat in the headers. He was very specific in his example for the ceramic coating he used being OK, that from his experience lean conditions are not usually responsible for discoloration or coating to come off. My headers were in fine condition with respect to the powder coating five years later when I sold them to get the current Muzzy header system which performs better with the larger carburetors I have adapted to the bike.

[skids]

Brant, as you have a wealth of knowledge in those matters, you know exactly what you are talking about, but you should "dumb it up" so that people like me can understand it.

[motoman]

Bonz, liked your response.

skids, plan on attending the Kremmling Rally and I'll explain it all to you, in detail if needed be.

[Bonz]

Brant, I appreciate your knowledge on this matter as it relates to heating scrap metal of a different elemental composition with a torch not being a comparable indicator of what a header will do.

[CaptonZap]

I am going against the flow here, however blue pipes can indicate rich. The mixture is unburned and continues to burn as it leaves the engine, creating extra heat the would not be there otherwise. That is why I believe so many of the V twins that have fueling devices with their new headers get blued pipes. They are shooting way too much fuel into the engine.

Another facet of that is that a retarded ignition timing doesn't start the fuel burn soon enough to have it completed when the exhaust valve opens.
Can lead to the same bluing. So a timing check wouldn't hurt.

Those of you who are buying the Habba Fright IR heat gins might check the temperature range on them. The one I bought years ago peaked at 700 deg F, as I recall. Pointing at some thing over that will probably not hurt it, but may not give you a good reading.

CZ

[flyingdakota]

will check spark plugs too....

Ok thanks guys!
I will pop out the s.p. when I get home and check the color of them. So the pipes are a dark blue to almost black, and it is not a double wall pipe I know that for sure. So here is my story....
Back in 2000 I bought the bike and went through the top end (adjusted valves, coils, pick ups, complete rebuild of carb etc.) I adjusted the float settings and played with the needle height and found the "sweet spot but ended up with the needle in the same position I started, the floats were all adjusted the same and I tried putting the airbox on but it choked it out....So that is why I went with the individual filters. I still had a stutter issue when I rolled the throttle on from around 4k to 6k and as long as I eased it on it was ok. Haven't worked on it since then so now I want to try and dial it in better and after sitting for the last 2 years it is a little worse and I figured I'd strip the carbs down again and try rejetting. I have a digital sync tool now too so I am hoping that will even help me better too.
Something for clarification too...what are you referring to as the "pods"
needles were 2.5 turns(2 carbs) to 3 turns (other 2)
Now on the fuel/air mixture and correct me if I am wrong....being an aircraft mech and pilot when you lean the mixture EGT (exhaust gas temp) will rise and the peak at best mixture (1100*F to 1350*F) and you can go past and it will start to cool (lean of peak) Now with that said wouldn't the richer mixture cause it to run cooler and not hotter? Just trying to adjust my thinking of this since the bike might be different because of the way the carbs are set up.
Thank again in advance for all your input on this!
Cheers!
Tim

[TopCatGr58]

Hey Tim,

The PODS are the individual pod filters, and the cheap EMGO brand have a prominent mounting lip that interferes with airflow on the inlet bell and your falling flat on it's face at 6K rpm's is classic for that type of interference. Take a look here for examples/info on them.
http://www.xs11.com/forum/showthread.php?t=8269

Next, Skids, I think you had a brain fart with regards to the pilot screws and jetting adjustments....if he's 3 or more turns out of the pilot screw=making the F/A richer, then the pilot jet isn't large enough, and needs to be enlarged so the pilot screw doesn't have to be 3+ turns out. And if only 1/4 turn from seated and too rich, then a smaller pilot jet is needed.

Okay, Tim, you didn't say you used GENUINE MIKUNI jets, we have had lots of problems with aftermarket K&L and other brands of jets, they are sized incorrectly and can cause excessive richness and lots of tuning problems. The MAIN jetting guide says 2 sizes up for each type of mod....aftermarket pipes AND Indy Pod Filters, but need to drop back 1 when there's more than 1, so only 3 sizes up...ie. from 137.5 to 145, your 150's are 2 more sizes too large according to this guide....but it's just a guide...starting point. As has been said, need to COLOR the plugs with the throttle chop process.

Yamaha originally jetted the inner 2 cylinders slightly larger than the outer 2 due to less cooling for the inner 2 and so slightly richer was to help it run a little cooler and perhaps more even with the outer 2 cylinders, but they abandoned this just a couple of years into the production run. Richer mixtures will help the CYLINDER temps to be cooler due to the incomplete burning affect, but the EXHAUST pipe temps get hotter as was stated as the gases continue to burn there. Too lean causes the CYLINDERS to get hot, but not so much excessive heat for the pipes.

Has been some recent discussions regarding TUNING the pilot circuit with heat guns and exhaust pipe temps possibly helping to find the best A/F pilot mixture easier than trying to tune by EAR, rpm drop when too rich, etc.!

SO...ensure GENUINE PILOT/MAIN jets as a start.

T.C.

[Bonz]

Pods, they are the individual filters on each carb. Pod filters.

If the bike has sat for two years, think carbs in the grand scheme.

If it's the same symptom now only worse since sitting for two years, I would respectfully wonder if the carbs were truly clean, part for part and bit for a bit in each little passageway the first time. Did you take the rack apart so you had 4 individual carbs, remove all parts internally, soak the carbs, blast the bodies in all the orifices with compressed air and a use a fine wire and probe/poke through all of the passageways in all jets, especially the pilot Jets. If you have done that, then you did a good thing. Probably should be done again.

Still, check to be sure there's not a raised lip on the inside of each pod restricting airflow. Trim it down so it's smooth if so. Do the simple stuff first, see if there's a difference. If it is better but not perfect, look at my paragraph about cleaning the carbs. If you haven't done it to that extent that would be a good place to start.

[motoman]

+1 to Bonz's last post, with to make darned sure those main jets are Genuine Mikuni along with the pilot jets...having the swirly-q logo embossed onto them.

Thinkin' like T.C. stated, those main jets..if in fact Genuine Mikuni are WAY to rich. If they are aftermarket mains, guarantee they are too rich. The K&L or RD main jet brand are holed bigger, even tho sizing embossed on them show same as Mikuni main jets. Same goes for the pilot jets. That alone can cause the mixture issue bike is having. Remember to, attack ONE possible issue looking for improvement BEFORE going to another.

[skids]

Hey Tim,

Next, Skids, I think you had a brain fart with regards to the pilot screws and jetting adjustments....if he's 3 or more turns out of the pilot screw=making the F/A richer, then the pilot jet isn't large enough, and needs to be enlarged so the pilot screw doesn't have to be 3+ turns out. And if only 1/4 turn from seated and too rich, then a smaller pilot jet is needed.

T.C.

Dammit! Yes, major brain fart.