misfiring on rear cylinder

[fatfreddy000]

Sure I'll get her running well in the end for more than a few miles at a time that is, but early days putting right a decade of neglect.
Noticed yesterday morning the storm has started coughing and farting, missing a few beats and popping on the over run, also more irregular rpm across the range.
Disappointed as after adjusting the TPS resistance these symptoms had all but vanished- they're much worse now, although she does sound like an untamed beast.
On the way home she started missing badly and spluttering then I totally lost the rear cylinder.
Crawled home on the front cylinder for last mile.
It was a hot day and at the same time I had a failure of the earth wiring on the thermostat and lost the temp guage so am unsure how hot she got but fan was running..
I let her cool for ten mins and on starting the symptoms abated and gradually improved the more i let her cool I think.
Still got the cough, fart, pop going on and I'm sure the same thing will happen if I take her out again without some more tinkering. I assume I have an ignition system fault on the rear cylinder that is aggravated by heat. Maybe something is expanding or somehow causing insulation breakdown in the ht leads or plug caps.
I am awaiting arrival of an 18mm plug socket so I can check out the plugs, all wiring to coils and ignition unit seem clean and tight.
What I did notice is that if I pull the front or the rear plug cap and run on 1 cylinder the intermittent splutter and backfire on overrun seems to vanish.. Hmmmm?
I reckon its a simple matter of plugs, caps, ht leads or coils and hopefully not the ignitor or something else all together.
Just wondering if any other owners have ever suffered similar symptoms of missfiring and intermittant loss of one cylinder in regards to heat worsening the situation.
Lend me your ears and your storm knowledge once again chaps..

[tony.mon]

Check reg rec output.....

[Varastorm]

I had a similar problem a while back.

Like yours it was the rear cylinder. It happened mid ride on the way home, I'd been hammering it & slowed to 30 for a village when it ran very poorly, trying to buck me off violently. Above 5-6000 rpm it was great.

With no mechanical sympathy I got it home.

I swapped everything I possibly could around to home in on the issue. I tried different carbs, coils swapped over, ht leads & plug swapped, there was no difference, so I waited for new plugs to arrive in the post.

Plugs arrived, fitted them & bingo fixed. I never dreamt it could be plugs with the issues it had.

Heres the saga if your bored

http://www.vtr1000.org/phpBB3/viewtopic ... f46bbb85a8

I read somewhere afterward that there's a lot more strain on the plugs at lower rpm. Could be nonsense though

Hope you get it sorted & keep us posted