Acceleration just not quite there?

[Drumagician]

Ok, I just cannot get my bike running like everyone says they can run. I've read and read on this site and changed and changed my setups. Can I get some people to tell me what their carb set up is that works like it is supposed to? I only want suggested setups that include Mac 4 into 1 pipes (no baffle) and pod filters (pretty cheap filters I might add and could have something to do with it maybe; I think about $25 for all 4). I just reshimmed the valves, new plugs, wires, caps and butterfly seals. My coils are reading about 1.8 ohms which is slightly out of tolerance (spec being 1.65 max). Maybe this is a bigger issue than I think it is. It starts, idles and runs very well with the exception of it being a little slow off idle through 2500 rpm. But again, its not scary fast or even close to pulling the front wheel off the ground in any gear unless I dump the clutch off the line. I raced my brothers sportster 1200 today and he was somewhat keeping up with me. I think I should be blowing his doors off right? If anyone has some good setups, I would like to know. Thanks all.

[petejw]

i noticed a cpl of things in your post,
if your running the cheap emgo filters,
they have a lip that protrudes and partially blocks
of the vents at the back of the carb bell that can
cause issues.

with the early model carbs that have the vents
that attach to the air box, with these carbs its hard
at best to tune with pod filters, in saying that just
make sure the hoses have no restrictions.

fuel heights affect acceleration, at 25mm u might be
on the rich side, does the bike bog down when u crack the throttle?
theres a real sweet spot when setting the float levels.
i cant remember if your model had the 42.5 pilot jets, if so and
u put the 45's in then that would also make it run rich.

[natemoen]

I cant really give you any carb specific setting cause I am not there yet either but if your testing your carbs you should check both the primary and the secondary windings. Stick the ohm meter on the plug caps of 1 and 4 and if you are running 5k ohm caps you should get a reading of about 25,000 (coils and wires alone should be at 15,000) +/- I think its 10%. You can also check your ballast resistor which should be at about 1.5 ohms as well.

[natemoen]

fuel heights affect acceleration, at 25mm u might be
on the rich side

Actually Pete 25.7mm +/- 1mm is the stock float height for the early model carbs.

[petejw]

Hi Nathan,
yeah your right about the specs, but after spending a
few weeks of adjusting the float levels, i can tell you if
you set the float heights + or - the 1mm that yammy states
then you cld be in all sorts of trouble,
as little as .1mm in adj makes a difference, when i tried setting
the floats on the leaner side (up2 1mm) i then had to up the main and pilot
jets to compensate, not to mention the noises that the engine made.

best method i found for setting the float levels was to start at the stock
setting, if the bike lacked acceleration and lagged when hitting the throttle
then i would richen the floats by .1mm at a time,
if the float levels are set rich, then the bike would bog down under acceleration.

[natemoen]

Hi Nathan,
yeah your right about the specs, but after spending a
few weeks of adjusting the float levels, i can tell you if
you set the float heights + or - the 1mm that yammy states
then you cld be in all sorts of trouble,
as little as .1mm in adj makes a difference, when i tried setting
the floats on the leaner side (up2 1mm) i then had to up the main and pilot
jets to compensate, not to mention the noises that the engine made.

best method i found for setting the float levels was to start at the stock
setting, if the bike lacked acceleration and lagged when hitting the throttle
then i would richen the floats by .1mm at a time,
if the float levels are set rich, then the bike would bog down under acceleration.

I will agree with that. Each bike has its own personality and different bikes age differently!

[TopCatGr58]

Hey there Drumagician,

There's a jetting guide in the MISC forum. For indy pods and 4-1's, you would expect to raise the mains at least 2-3 sizes, ie., 145 vs. your 137.5 stock. The 45's pilots may be enough, but you may need to turn the pilot screws out a 1/2 turn each and then retest it's throttle response.

Yes, some pods can interfere with air flow, a quick test would be to do a short run down the street/highway without the filters on and see if it responds any differently. Folks having troubles with the pods reported difficulty getting above the 5-6k range!

It's also a known anecdotal "fact" that aftermarket pipes, especially 4-1's and especially MAC's can be detrimental to the low rpm torque/power. 4-1's move the power band a bit higher, into the 5-7+ k range. For a better lower rpm response, you might want to look into putting some baffles in the muffler!

Also, remember, these aren't Harleys, where HD's power band tops out, OURS is just starting! I have 4-1 pipes, and Indy pods, and I don't run below 2k rpm, usually closer to 3k, let the engine RUN and you'll find your power!
T.C.

[Drumagician]

TopCat, I have looked a that guide and per my mods it says I should be up 6 mains which I did and it was definately too rich, so went back to stock. I read one post that said without MAJOR mods, there is no need to rejet the mains, just make adjustments with the float height which I have done. I suppose this method may or may not be true but he sounded pretty confident. I think that maybe another main size or two might work for 3500 and up but just cruising around taking off from stops, the take off is very annoying. These bikes should be a consistent acceleration from a stop right, not a very noticeable transition at about 3000?

[natemoen]

It is a pretty noticeable transition when you go from the pilot jet to the main jets!

[yamtom]

pretty much the same

Hi,

I have the later carbs, emgos, and harley muffs on original head pipes. I have almost exactly what youre describing also, mine wont lift the front wheel except in extreme conditions, such as clutch drop , playing games with rolling the throttle on and off in low gear etc. There is a significant change in exhaust note above three thousand and harder accel along with that. There is a similar change in exhaust at about five thousand, where it really starts to bark and accel after five is serious. I dont consider this unusual but maybe it is. I have the floats set by the book . You guys saying four thousandths of inch float height diff makes a big diff surprises me greatly. I had another eleven, thirty yrs ago, a I believe a 79 but maybe a 78, and I do believe that bike ran a bit harder, but early models do run harder, I was lighter by thirty pounds , then also, haha. That bike was stone stock, except for a bit of a hole in the bottom of each stock muffler from rust thru, it sounded good though. And, that was an era where the eleven was the vmax of its day, and my experience was less so I would have been more impressed with it then.

To give a comparison, I have a B12 zuki, with supposedly 120 horses at the rear wheel, that bike, runs almost from high idle, like bonkers, lifts the front wheel in low gear with just significant throttle application, pulls much stronger than the yam 11 by a factor of SCARY ! I am a tall ,very heavy rider, at six five and 290 full dressed , so I do tend to sit back towards the rear wheel. You guys getting the hard wheelies on the 11 in most gears, must be very very light or youve got bikes running much much harder than mine.

[yamtom]

time run out

Hi,
I tried to edit the above post to add info, but cant so here it is.

I have too many toys, I also have a zuki 109, huge v twin but two hundred pounds heavier. The 109, has 128 flywheel hp, so they say, about 105 at the wheel. The 109 and the 11 also have almost identical quarter mile ets when they were new.

These bikes have a totally different feel, and I would say the nine is a bit faster than my 11 but not by a lot at all.

Now lets go to an even more potentially significant factor than hp , carb tuning , bla bla, and that is the internets potential ability to turn a good runner into a wheel standing monster in the eye of its owner. I am NOT saying that the guys on this board with these wheelstanding monsters are goofing us, but there are no actual quarter mile time slips with speeds to prove anyones point here. I love the guys on this board for their mechanical genius and the warm feeling that I get when I get an answer to a question thats obviously from an Elevener genius that has a lot of experience with the xs11 s. The speed of you guys es answers never fails to amaze me, its like there is a genius here online at almost all times, wow ,,is all I can say. You all have a good one and keep the wheelie stories coming.

[Drumagician]

Can anyone else confirm the noticeable transition from pilot to main jet? I have ridden many other bikes in the past... harleys, custom choppers, new sport bikes, and there has always been a nice consistent acceleration thru first gear. Taking off on my bike from a stop with moderate throttle feels like I'm taking off in 2nd gear when I know I'm not and at 3000 rpm its a totally different bike.

[yamtom]

yes transition

Hi Drum,

I just reread your original post, that four into one is gonna kill your low end without a baffle, thats what there seems to be general agreement here on this board from all the hours that Ive spent reading here. I confirm, there is a noticeable transition from the pilot to the main jets. Below three thousand, my 11 feels like what I consider a typical honda type power band, it is linear feeling, meaning more throttle means more acceleration but not explosive at all. I do NOT consider this to be a problem, and certainly, I consider it quite enjoyable, not the unpleasant feel that youre describing. I have all stock jetting on the late carbs and reread my previous posts for other info too. I very much think TC has the answer for you, put a bit of a noise reducer in that thing and your bad feeling transition may very well go away. I do recall my 79 or 78, whichever it was, did feel a bit faster and did have a more rounded power profile, that is, it was a bit surprising right off idle, but that bike, was stock and had stock pipes with the perfected by yamaha back pressure.

[Drumagician]

"I confirm, there is a noticeable transition from the pilot to the main jets."


Well this makes me feel better because I have done everything I can think of to rid this issue when in fact, it may not be fixable. If I can get some other people to confirm, I will just live with it I guess. As far as the baffle in the exhaust is concerned, I like being loud, and I would not be able to enjoy riding as much without being so loud. Is there any type of baffle or maybe torque cone for this exhaust that won't quite me up so much?

[Larrym]

Square Pegs and the Oval Holes...

Ok, I just cannot get my bike running like everyone says they can run. I've read and read on this site and changed and changed my setups. Can I get some people to tell me what their carb set up is that works like it is supposed to? I only want suggested setups that include Mac 4 into 1 pipes (no baffle) and pod filters (pretty cheap filters I might add and could have something to do with it maybe; I think about $25 for all 4). I just reshimmed the valves, new plugs, wires, caps and butterfly seals. My coils are reading about 1.8 ohms which is slightly out of tolerance (spec being 1.65 max). Maybe this is a bigger issue than I think it is. It starts, idles and runs very well with the exception of it being a little slow off idle through 2500 rpm. But again, its not scary fast or even close to pulling the front wheel off the ground in any gear unless I dump the clutch off the line. I raced my brothers sportster 1200 today and he was somewhat keeping up with me. I think I should be blowing his doors off right? If anyone has some good setups, I would like to know. Thanks all.

If I had your situation and set up I would be doing exactly the same thing: Giving a shout out to see exactly the carb/exhaust setup that truly eliminates any "lag" resulting from the aftermarket intake/exhaust.

I recall my automotive tech class including a trip to Maremont Exhaust where we participated in the design of an aftermarket exhaust for a Buick Riviera. The whole focus of making any alterations in the exhaust "flow" was to NOT have the engine require any further "tinkering" by the owner, To achieve that it involved quite a bit of test equipment far beyond what the average dude has access to. (Dyno, exhaust gas analyzer, flow rate/temp sensors, etc.) Sure the goal was to achieve a performance "Boost" but not so much that it would require a trained technical staff and a pit crew to compensate for the "change" that the exhaust made.

Not the same thing with the 4-into-1's for our bikes. I think it's just expected that the owner will have to fuss with jetting and or other changes to regain the lower end grunt and the smooth "transitioning" that the OEM exhaust achieved. What those changes are and by how much is something that can be very time consuming to determine. (Change/Alter settings<TEST> Change/ alter parts<TEST> repeat till you've got it right...)

If someone here among the owners really has dialed things in then I say that sharing those EXACT details certainly would cut short any "Trial and Error" process you're in.

But I'm not exactly sure that it's really "practical" to achieve that smooth transitioning. By design, the 4-into-1 shifts the powerband (for lack of a better term...) into a higher RPM range. That's what it was designed for and is supposed to do. I get the feeling that any great efforts to regain that lower end torque/performance is pounding really hard on that square peg in order to get it to fit into that round hole.

Instead, I would embrace the powerband as changed by the 4-into-1. If the bike just doesn't have the Backside Dyno numbers at the lower rpms then it's made up for by the gain at the higher rpms.

And no...I don't have a 4-into-1 exhaust on my bike. It was a deliberate choice on my part. If someone really has got it dialed in then I am looking forward to them sharing the EXACT details of how they pulled the rabbit out of the hat on this one....


I mean I might wanna get a 4-into-1 someday, right?