Dead coil?

[BillingCBR]

Hey guys, just in from a blast on the '23, was going lovely overtook a line of traffic at full tilt, bike was running great, then from nowhere it started bogging down really badly, as if it was out of fuel, so switched to reserve, the problems cleared up a little and then came back even worse.

The bike won't rev past 6k, and dies with more than maybe a 1/5 turn of the throttle. I limped it home and drained the carbs to check there wasn't any water in there, but the problem has persited. I dipped my hand in cold water and literally brushed the down pipes (being aluminium they were f*cking hot!) the 2 outer ones were scalding hot, but the centre 2 were merely slightly warm. Would it be safe to write the coil off for the centre cylinders in some way or another? I'm hoping for a loose connector or broken wire, bad earth etc but am preparing myself to have to buy new a new coil, so will do the plugs and leads while i'm there

[Wozza]

Checked your fuses and clock connections? Sounds like the limiter kicking in.

[BillingCBR]

all fuses are fine, and there's no loose connectors, it doesn't feel like the limiter (that kicks in at 5k for the limp home mode i think) its more like a horrific misfire, it will occasionally rev up to 6k, but is properly lumpy and usually won't go past 3k. I tried to locate which cylinder is giving me problems, seems its running on the 2 outer, the right hand middle might be a bit off, but the middle left is definately dead, on sunday I'll whip the rocker cover off and have a look for anything out of place on that one (loose shim, broken rocker, damaged valve etc) I'll see what the spark plug is like aswell, (colour/damaged electrode) and maybe whip the head off, see if anything is amiss with a valve. Will give me a chance to have it ported, tiny skim and reseat the valves if it's all ok at the least, if not I'm going to insure the VFR and take this to bits, give it a proper overhaul

[Wozza]

Good plan. Maybe check the spark on cylinders 2 and 3 first? Even easier if you've got a spare plug lying around.

[BillingCBR]

It's really only number 2 giving me trouble, number 3 is just a little bit slower than 1 or 4

Will take plenty of pics on sunday if I find anything. If it turns out that it's dropped a valve or something, I'll be looking at either 444cc big bore and stronger rods with a ported head and reground cams, or fitting a CBR600 lump over the summer, and maybe going f.i next year, I'm liking the idea of an 80bhp CBR

Did hear of one with a mk1 fireblade engine, but would most likely wreck it in 5 minutes