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Discussion Starter #1
since putting the bike back on the troad last week, the rev counter has started doing a funky new dance, and the bike has acquired a new missfire/stutter.
when i am sat at aprox 100mph, the needle will spend most of its time at the max, 13k rpm. occasionally fluttering, but when accelerating, beyond 5k rpm the needle is all over the place, and the bike stutters and coughs, as though for a fraction of a second it is hitting the rev limiter.

basicly, my question is: does the ignition control unit read the same feed as the rev counter, or does the rev counter tell the unit what is going on?
is my problem likely to be a sensor or the rev counter?
i doubt it is the ignition control unit, as it was replaced only about 3 years ago max!
 

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Hi,

The rev-counter is fed by the coil to cylinder 1. It may be worth you changing the coils around to see if you still have similar problems, but without the rev-counter fluctuation? Doing this, you can also take a look at the casing to see if there is a tell-tale small split.

Geoff

ps. Fyi, I have had the coil to cylinder 1 go and just replaced this one coil and everything has been fine since. The dealers appear to suggest you should replace all three, but I think this feed to the rev-counter, or its mounting location, just makes this particular coil susceptible.
 

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Discussion Starter #4
i have repaced one coil already, and everything was fine for a day, but it may be coincidence.
i shall try the now spare coil in the place of coil 1 and see what happens.
ta mate
 

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i have repaced one coil already, and everything was fine for a day, but it may be coincidence.
Hi again,

My instance was slightly different, so it is good that you are approaching this methodically, just in case the problem lies elsewhere.

In my own case, I found the outer plastic casing was splitting slightly from the silicon filling at one point on the coil. This slight split could allow some dampness in (I assume), so on a warm dry day the Sprint ran perfectly, but on a damp day it soon dropped onto two cylinders and the tacho stopped working.
- Perhaps it could have been this kind of coincidence that "everything was fine for a day"?

Good luck,
Geoff
 

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Discussion Starter #6
as suggested, i checked coil for cylinder number 1, and low and behold, there is a gap between the black casing, and red silicone base.
swapped it for the apperntly "good" spare, and hey presto!it all works! oh and it turned out that the vaccuum pipe for my scot oiler had popped off too, so that just compounded the issue!
thanks for your help gents, she now runs alot smoother and crisper!
 

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Discussion Starter #7
once again, it started missing a day or so after i though it was fixed.....
but today i fixed it!
i went to my mates house, where my old engine is knocking about, and retrieved the pulse coil.
oh wait......
i never actually got round to fitting it, instead, on my way home i just filled up with fuel, and from that moment on, it never missed a beat!
its strange, it is the fuel station i used to use up until i moved to another town last year, so i wonder if i9t is all purely down to bad grade fuel in my new home town???
could this really give all the effects i had?
 

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Chances are it was the coils, there is that feed back loop in the system which goes thru' #1 coil(though I want to say #3 for some reason), which if going south will cause the erratic behaviour of the tach. Misfiring, or slight inconsistencies in running continuity is generally electric in cause. If fueling is the issue, my experiences are that the stuttering is more pronounced than that of an electric misfire and will generally lead to stalling. These bikes if left for a week(especially in winter) or so, seem to suffer from some kind of electrical discharge, a parasitic loss - which manifests itself by a build up of 'crud' about the mating surfaces of the low tension spade connectors and their coil side counter parts - a 'Thorough Cleaning', some dielectric grease and a little crimping action to affirm the join, will often cure the misfire - of course inspecting the little buggers for cracks and obvious flaws that might be the fault is also a worthwhile moment - as you know. It's an inexpensive process too!
 

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Discussion Starter #9
it started stuttering again, so i decided to change the pulser coil, i found that where the wires go into the unit, the red insulation had cracked.so changed it.
all seems good again, but for how long this time?
 

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Great stuff - happiness, you can ride smiling again! I've noticed that the sensor's tend, when they go, by becoming heat sensitive - once the engine is fully warmed the misfiring begins. It's all a process of elimination I suppose - battery, plugs, coils, spade -ends, HT, Crank sensor, solenoid, clutch kill, kickstand switch, loose earth.... vac lines, fueling - still fun figuring it all out!?:) Maybe someone will be inspired to make a spread sheet of 'issues' and their correction - Wiki style, perhaps?
 

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Discussion Starter #14
i think a flow chart should be made!
i couldnt do it, cos i run too much off "feelings" ie, it feels electrical, or it feels like fueling, i cant describe what makes each one feel different
 
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