Guys,
I'm being a bit lazy in asking for help here but it's seems a while since we had a collective diagnosis thread going in the cane section. I know the possible answer to my question is locked inside someone's memory around here so out with it pronto.....pretty please!

The bike has developed a misfire, or what feels like ignition cutting off at around 100 MPH. Riding home from work on Thursday a wound her up a bit and suddenly she was jerking and holding back then suddenly pulling hard again.
Slowing to around 79-80 and the symptom stopped.
I took the plugs out today and all looked good except for a slightly rich mixture on No. 3. Cleaned, gapped and refitted she starts up fine and runs smooth as butter. No. 3 is definitely firing.
A half hour ride today, varied speeds showed no symptoms at first. After she was well warmed up I gave her some gas and again, just over 100 the misfire started again; slow down a bit and all is well.

It's not fuel starvation. I know what that feels like as I almost always hit reserve before refilling. This is a pretty definite ignition problem.

I don't have time to tear her down but will be re-diong the CCT mod in a month or so at which time she'll be getting a serious portion of TLC.

In the short term.... what can you all think of that may be an obvious culprit?

 

Is this bike from France or Germany cause i know they were restricted over there...

 

Obvious easy "Armcahir Sunday" stuff to check Henry -
tank breather, petcock & those little
plastic vanes in the air box elbows ( are they missing) ?

Elbows collapse under wot if they are not there and cause the
bike to bog down at 90+ too much juice not 'nuff air getting in

after that float levels etc, - I'd check 'em

 

Thanks Sproc,
Grey matter doing it's usual stuff.
Sunday armchair stuff. Gawd, you've seen right through me.
Given that I had her up to warp factor ten only a few days before I doubt there's much that's happened to the fuel side of things. I've cleaned the tank out several times over the last few months and boy, there was a lot of rust in there. New fuel filter fitted not long ago.
I'll be compiling a list of things to check from your suggestions though.

Dragon,
This bike is no import (except from Japan originally) and she sure isn't restricted.

 

How does it do on RES setting? Just asking because the main fuel tube could be restricted. Just an easy thing to check to see if any difference.

 

Good question TBT but again, there's no problem with either main or res tubes in the tank. Both behave as expected and cleaned recently. When I got the stutter today the tank was completely full.

By the way, I hadn't mentioned this before but about 6 weeks ago I ran the tank near to empty and managed to get 22.5 litres of fuel into it at fill up. I was a little gob smacked given that it's only a 22 litre tank. Anyone else experienced that? Mileage was about 230 on the tankful.

I digress.....

 

it seems I have a loose connection somewhere. Whenever the back wheel hits a bump particularly hard she cuts out momentarily. It happened today at around 35MPH as well as at speed. Random impact.
Ah well, I'll have a fiddle and let you know what I find.
At ease men..... oh, you already are.

 

Henry, when I first got my bike the ignition control module would unplug when I hit a bump. One time it totally unplugged and shot out of the holder. I was lucky I didn't loose it out on the road.

It sits in a rubber holder that gets weak over time and due to the angle the ICM pops upward when you hit a bump. Perhaps you should take a look at it. There's an easy fix if that's the problem.

 

TBT,
I was also thinking at looking there so I think you for what is probably the answer in advance of me having a delve.
Funnily enough the problem has stopped altogether today even after riding over some quite rough surfaces and getting nearly 350 miles on in the last 24 hours through absolutely ****e weather conditions.
My ICM is probably lining its self up for a medal winning dive into the road as I write.
I will update what I find to corroborate your learned hunch.
Cheers mate.
H

 

I checked the ICU connection at the weekend and found it to be sitting pretty.
Funny, after 60K miles on 1000F's it's the first time I've ever taken the seat cowl off and even seen the ICU. Just goes to show how reliable the electronic units are.
Symptoms are gone anyway. She's running faultlessly again. No idea what caused the misfire.
Glad it's business as usual, especially given the ultra wet and near freezing weather I've been riding in the last few days.
Snow and sub zero temps might see me off the road for a few days, maybe......

Anyone got any other debugging suggestions? Just trying to get answers that may help others in the future.