low speed miss

[mick12]

The 12 has a low speed miss at idle and mybe upto about 2000 revz its a pain in the ass at lights idles rough as guts not knowing if it will stop. Gave it a bootfull on the way home today and its all fine right through the revs apart from low speed it a 2000 model only has 41k on it and regularly servised but dont know if the plugs have ever been changed yet. on the way home yesterday white shit (foam or paper shred )was blowing around the road for about 10 ks thought the air filters may have been clogged had a look and all was good . any ideas

[MAXUMIS]

Mate , it sounds like it could have an intake leak or the valves need shimming . Your best bet is to let it idle for a bit and find out what cylinder is missing buy feeling the primary pipes then go from there .PS use common sense when testing .EDIT the coldest pipe is the cylinder that's missing

[mick12]

just had a look at the TBs without removing them on the vacume nipples left to right at the front is a hose then what looks like a bit of broken hose and no seal all others have hoses except the outside nipple on the far right body which is capped should the inside far left nipple be sealed the broken bit of hose is hard and once in it s life i would say was clear pvc

[MAXUMIS]

just had a look at the TBs without removing them on the vacume nipples left to right at the front is a hose then what looks like a bit of broken hose and no seal all others have hoses except the outside nipple on the far right body which is capped should the inside far left nipple be sealed the broken bit of hose is hard and once in it s life i would say was clear pvc

That sounds like the source of the problem . Replace all the vac hoses if they have gone hard ( and block offs) , any auto store will sell vac hose to suit your needs .

[MAXUMIS]

I think the A models used vacuum to activate the Kleen air system , if so your best bet would be removing it as it will help a little bit with performance (less volume going into the exhaust system) and getting rid of another problem that could be in the future.

[mick12]

A's do use vacume for clean air I have plugged the open piece of hose and the miss is still there it seems like a plug is only firing about 75 percent of the time the miss isnt at regular intervals so i guess i will have to strip it half down and have a good look at everything

[MAXUMIS]

So now your saying it misses 75% of the time ?

[mick12]

I am saying it has an IREGULAR miss [ not at a constant and predictable time intreval like a high spot on a tyre] about 25 % of the idle time and 75 % percent its ok it like a plug is trying to fire but just cant quite do it i cant think if a better way of explaining it

[oldman]

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[MAXUMIS]

I am saying it has an IREGULAR miss [ not at a constant and predictable time intreval like a high spot on a tyre] about 25 % of the idle time and 75 % percent its ok it like a plug is trying to fire but just cant quite do it i cant think if a better way of explaining it

Mate if its an intermitted misfire (meaning the cylinder comes and goes at its own leisure ) its more than likely a bad plug or coilpack . It sounds like a electrical problem if the cylinder popes in and out at its own will imo . I would still replace all the broken/hardened vac lines .Find out what cylinder is braking down and go from there.

[mick12]

just ran self diagnostic lookin for a faul code and swaped out the ecu with a new one and no codes were displayed on either of them if its a coil the ecu registers a code so now it time to go under the plastic and start pulling things apart the stealer has done my services in the past so i guess i will learn something new

[MAXUMIS]

The ecu will not always pic up the problem then its intermitted ,we see it a lot at work . If it was me I would get the bike to make the problem and find out what cylinder is dropping out , when you find the cylinder that is causing the problem swap a coil pack from another cylinder ( throw a new set of plugs in as well) and go from there .

[Smitty]

...start with a plug change
and at the same time check and eliminate any vac leaks

[Gosling1]

change the plugs, that will fix it.

[mick12]

Have changed the plugs ,miss is gone. Removed kleen air vac pump and added 4 vac hoses to allow easy sync of the throttle bodies, just pull them out the side and connect the gauges. Found the bottom throttle cable is frayed. I noticed that it rubs on the edge of the exit tube because it doesent run out straight like the top one, any body else that has a push pull would be advised to check theirs at rest the fray is actually back up in the sheath and is only exposed from about 1/2 throttle so unless you twist the grip you may not see it. I would call this a design fault because of the way the cables align with the pully .Tomorrow I will start milling up a set of block off plates for the reeds. After seeing pics and stories of burned valves decided not to do the crancase vent mod I guess its ok for race teams who can afford rebuilds on a regular basis but i think the mod leans the mixture and aids in the burning unless you are tuning up