irratic running

[sarrebmat]

i have a xs 1100 midnight special, i am having great problems getting it to run as it should. it keeps popping and cutting out at low reves than as i hit the gas it misses and then overrevs. I have had the carbs off and cleaned everything, new air filter, and repaired the diaphrams as they had holes in them. it only seems to miss and pop (through one exhaust???) when it does run long enough for me to ride it seems like half the power is missing , please can anyone help me.......i have also had the coils tested and they are ok.. new plugs also

[TonimusMaximus]

Do you still have an airbox? When the bike is running, try putting your hand over intake to choke it. See if RPMs change. If they don't, suspect the carb boots. I still have to repair mine and find out. I've have some similar symptoms.

[TopCatGr58]

Fixing a hole!

Hey there Sarrebmat,

Have you had the bike long, or is it a new acquisition? A bit more history on the bike can be helpful in trying to diagnose long distance. With one pipe/side acting up, it could very well still be fuel supply, it's a Special, and the Octopus is known for causing trouble, along with the petcocks, so you'll want to ensure that you are truly getting fuel flow to both banks of carbs!! Was the fuel old in the tank? You said you cleaned the carbs, did you actually disassemble the jets, needle valve seats, and such and give it a thorough cleaning??

How did you repair your diaphragms? Are they still sliding easily up and down, or did the repair cause them to get too stiff? With the Air box off, you can observe the slides in operation to ensure they are moving while the engine is running, but they usually only will pop up under strong accelleration from low rpms, cause on the center stand, there isn't much load, so they don't develop much vacuum. I was surprised to see this when I did a slow rev and watched them, they barely rose. Then I would crack the throttle and they would pop up and even oscillate a bit until the revs caught up. You can also push them up manually with the engine off, and put your finger over the top arched opening, they should not slide down, or slide very slowly until you remove your finger, then it should drop, but if it slides down with your finger over it, then your holes are still there, or not fixed.

Also, could be your pickup coil wires, on the lower left side of the engine under the cover plate, do a search in the tech tips and the forum to learn about checking them.

This should get you started in the right direction. T.C.

[sarrebmat]

thaks for info, i will try all you said. I did dismantle the carbs fully, except two small jets that had been sheard off so i couldnt un screw them this could be the prob, i will also check the pick up coil. Thanks again for your help, i will keep you posted with the results