SP 1 misfire

[bob the builder]

Looking for any ideas here as to what might cause the SP 1 to suffer the occasional misfire. By that I mean when accelerating from low revs I get the occasional splutter like its firing on one cylinder, it can happen hot or cold. It lasts for a couple of seconds only.

Bike has just been serviced by Honda dealer who could not recreate the fault during test ride, new plugs fitted etc.

Might a coil be failing?

Any suggestions as to what to look at?

Ta v much

Bob.

[benny hedges]

when you say they serviced it, did they fit new plugs?
only asking cos the proper lazer iridium plugs are like £20 a piece....

has it got a power commander fitted? you tried unplugging it?
or reloading a base map off power commander webby?

air filterS - there are 2 air filters, one may be a bit shitty.

have you done the flapper mod? and if not why not!
if the flapper servo (in front of instrument pod, looks like a horn) vacuum hose has just been disconnected and plugged, maybe the plug has come out and its sucking air in,

usually spluttering is a sign of a weak mix - rich is more of a flat boggy feel.

if you think its ignition related, check the sidestand switch and make sure the stand bolts are good and tight as loose ones caused my drop the other week :/
and the bike also has a tilt switch but dont ask me where its located.... - maybe ask on vtrsp.com or the o/c on fb as its pretty active there.

just a point on that - if you ever have the misfortune to drop your bike, it wont run when you pick it up. you have to remove the key, rearm the immobiliser, then switch on as normal and it will clear the tilt sensor.
i nearly flattened my battery trying to get it going lol....

if you are still stuck, a dyno run will prove if its fuel or ignition related.

[bob the builder]

Yeah, new plugs specced for the bike fitted at service. Air filters given clean bill of health.

Power Commander fitted and unplugged just now, fault still there.

Flapper mod not done, standard bike completely.

I will have a check on the bolts tomorrow.

Thanks

Bob

[benny hedges]

Flapper mod not done,

pull the pipe off the servo diaphragm (in front of the clocks) and plug it. (the vac pipe - not the servo)

enjoy

[bob the builder]

Did that to my last SP 1, does it really make a difference ?

[benny hedges]

yes mate.... if you ride it hard enough you will definately notice the kick in the midrange.

as part of the emmission control system, the vacuum servo starts to close a flap in the intake duct at around 6000rpm, supposedly to reduce intake howl from the airbox.

obviously you want this howl... and you also want the intake duct fully open at all times, especially when giving it beans.
the maf sensor compensates for the extra airflow - it doesnt make the mix weak - though there is a custom map on power commander site to take advantage of the flapper mod

you can go a step further and completely remove the flap (you can see it on the left of the intake duct, about 3" in)