Engine stutter under acceleration Happy 4th of July

[mwsxj1100j]

Well, it has been a while since I last posted anything. My XJ 1100 is running as best as can be expected. I do notice that under acceleration even when the engine is warmed up under acceleration in any gear the engine stutters. I am thinking that since this bike has a vacuum driven electronic ignition advance that there may be an air leak in the hose that runs to the boost sensor. Although I am not sure.

I did eliminate the fuel octopus vacuum fuel shut off which now in hindsight I looking to replace since if I do not turn my fuel Taps off the carburetors overflow in the engine floods after sitting for a certain amount of time also that I do notice that fuel leaks. I want to replace the vacuum operated fuel shut off unfortunately I lost the spring to said shut off does anyone know if I could just grab a spring out of a pen with that work?

But as for the stuttering does anyone know what could be causing this other than that she works fine except for the popping out of first gear if I go over 3000 RPM I believe there's a bent shift Fork that when I have the money and the time and the ability to maybe have the fork replaced.

I still have issue with clutch slippage under hard acceleration in 2nd gear but I think that since first gear is acting stupid with the FED Fork I start out in second gear I think which is probably prematurely wearing the clutch. So I take of slowly. But if anyone knows what could be causing the shuttering or stutter that's what you want to call it it be greatly appreciated. Thank you very much have a happy and safe 4th of July.

[TopCatGr58]

Well,

This info will probably make your 4th not so happy, but it's a common occurence. The 1st gear going bad first in the later model years after the kickstarter parts were eliminated, the 2nd gear going on the earlier models WITH kick starter, but both eventually will go bad! See tech tip on what's needed to fix it...hope you're into mechanic work!?

http://www.xs11.com/forum/showthread.php?t=5090

T.C.

[motoman]

Well, it has been a while since I last posted anything. My XJ 1100 is running as best as can be expected. I do notice that under acceleration even when the engine is warmed up under acceleration in any gear the engine stutters. I am thinking that since this bike has a vacuum driven electronic ignition advance that there may be an air leak in the hose that runs to the boost sensor. Although I am not sure.

I did eliminate the fuel octopus vacuum fuel shut off which now in hindsight I looking to replace since if I do not turn my fuel Taps off the carburetors overflow in the engine floods after sitting for a certain amount of time also that I do notice that fuel leaks. I want to replace the vacuum operated fuel shut off unfortunately I lost the spring to said shut off does anyone know if I could just grab a spring out of a pen with that work?

But as for the stuttering does anyone know what could be causing this other than that she works fine except for the popping out of first gear if I go over 3000 RPM I believe there's a bent shift Fork that when I have the money and the time and the ability to maybe have the fork replaced.

I still have issue with clutch slippage under hard acceleration in 2nd gear but I think that since first gear is acting stupid with the FED Fork I start out in second gear I think which is probably prematurely wearing the clutch. So I take of slowly. But if anyone knows what could be causing the shuttering or stutter that's what you want to call it it be greatly appreciated. Thank you very much have a happy and safe 4th of July.

.....gotta' correctly fix all those issues before even thinking about a diagnoses.

[motoman]

BTW, clutch slippage is highly likely due to incorrect adjustment of throw-out bearing assembly, not issues with with clutch fiber disc. Clutch LEVER adjustment HAS to be totally backed off before adjusting throw-out bearing assembly, which is under to outer round cover on engine right side. There's several links/threads here explaining that simple adjustment.

[mwsxj1100j]

Engine Stutter

The carbs on my bike have never been quite right. The engine stutters only under hard acceleration. The only reason it pops out of 1st gear is due to a hard down shift most likely a bent fork if I start out slowly and don't exceed 3000rpm then shift to 2nd, and accelerate gently there is no problem. One issue I have that is a big issue is when I stop the bike if I forget to turn off the petcocks the bike will flood. I tried running some seafoam through the carbs to hopefully clean out any build up in the carbs. I don't quite recall having this issue last season. I am just wondering if running some premium through through the carbs if that might help. I feel it could be a fuel starvation issue. I don't know all the in's and out's of carbs but I understand that there are a series of jets that feed the engine fuel at different speeds and I am just wondering if that first series of jets are plugged if maybe the premium fuel might clear things up but I'm at a loss. Other than that the bike seems to behave well it handles very nice compared to my friends FLH that I've written a few times this season. The Harley-Davidson is nice but it's so incredibly heavy and I like the lightness of my bike compared to that 800 plus pound Beast of a Harley. I just want to get my bike running right.

[bikerphil]

Clean the carbs and it will run better, ethanol in the fuel sucks and clogs up passages. Check for worn parts while you are in there. Then do a sync and see how it goes.

[Incubus]

At the very least you have to clean the valve needle and seat inside the carb (that's where gas comes into the carb). If working correctly the float will close the needle valve when the carb is full of fuel. The fact that it is leaking gas if you don't turn off the petcock tells me either the needle or seat on one or more of your carbs is dirty.

The carbs have to come off to clean the needle valve. IF you have any mechanical ability, do not fear pulling and servicing the carbs. I had mine ('79 Standard) off this morning. After you pull them about 200 times, the carbs come off quickly. I can go from fully assembled bike to carbs on the bench in about 12 minutes. My carbs have been off many, many times.

On second thought, maybe you ought to wait for someone who only had to take their carbs off one or twice. The level of expertise may be worth the wait.

Patrick

[skids]

On second thought, maybe you ought to wait for someone who only had to take their carbs off one or twice. The level of expertise may be worth the wait.
Patrick

Haha! That would simply be a stoke of luck Patrick.

[TopCatGr58]

Hey again,

Okay, just as another member with leaky carbs found out, the later model carbs not only have rubber/viton tipped float needle valves that can compress/get grooved and even breakdown, but the seats also use a Viton O-ring to seal it, and it also can breakdown and shrink, and then it will allow it to leak as well. SO...you WILL have to take the carbs off to clean and replace these parts.

Now, with them leaking, they could be flooding a bit and that can cause problems with throttle response and such. Now the XJ has the centrifugal advance curve programmed into the TCI. The Vacuum adv. curves are also programmed into the TCI but are triggered by the vacuum sensor box. But the vac. adv. portion of the timing curves are more for providing fuel economy during cruising mode, and it actually releases/retards excessive amounts of timing advance back to the more power producing point of ~35 degrees BTDC which is controlled mostly by the TCI and just the engine RPM itself, so I don't believe any stuttering in other gears under accel are being caused by the vac. adv. module.

You're right in that there are several different ports in the carbs that provide fuel at different throttle inputs. The Pilot jets and circuit are responsible for the low rpm response up to about 3-4k rpm. That's where the carbs transition into using the MAIN's. They don't clog quite as easily, BUT they and more likely their emulsion tubes(Main Jet NEEDLE) can get gummed up and clogged, and that can also cause poor throttle response. So...again, getting into the carbs to a proper cleaning while repairing the float seat O-rings and float needles looks to be in your future.

You can try to use some SeaFoam or Techroline fuel additive/cleaner in the gastank, about 1/3 of a bottle or so each tank, and run it through to see if it might provide SOME measure of cleaning/clearing the passages and gum/varnish from the carbs/jets/emulsion tubes which might help with the throttle response, but it's a bandaid approach to major surgery!

If tearing into the carbs seems too daunting, I'm sure there are several Xsives in your area that would be willing to lend a hand to HELP you, not necessarily do the job, but assist you in doing it so you can learn and get it done right and relatively cheaply vs. trying to get a dealership/bike shop to do it! Also be sure to get GENUINE MIKUNI parts, we have found aftermarket are inferior, incorrectly sized/metered and just add to the problem!

Your bike has the newer 3 ohms style coils, but both your plug caps and wires can still develop corrosion and cause weak/poor sparks, so taking the caps off/unscrew from the plug wires, inspect central wires, if green with copper corrosion, cut of 1/4" at a time till clean coppper wire, and also clean screw inside cap, and then reinstall. While at it, Ohmeter the caps while off, should only be ~5 kohms, if much higher, then internal resistor and spring/contacts have corroded or gone bad. You can take them apart at the spark plug end with a straight screwdriver, remove parts, clean and retest/ohmeter resistor piece. If still way over 5K, then replace caps. Sometimes engines/carbs have electrical problems!

T.C.