Triumphrat

Skidpan · 05-17-2005, 05:42 PM

Hello All,
A plea to all the technically minded ones out there.
A long-ish story but if you can advise/help, it would be nice.
Last year, i had an occasional misfire, over 6000rpm that you sometimes didn't feel, but was visible in the way the tacho needle flicked down and up very briefly. The higher the rpm , the more noticeable it became. Long story cut short, a new ignition key very nearly completely solved the problem for a while, perhaps 2000 miles, with just the very occasional hiccup. That in itself I will never understand. Now the misfire is back. Under gentle acceleration, up to about 6000rpm, all is fine. Over that, sometimes is ok and other times it misfires/stutters. Bigger handfuls of throttle can cause the misfire at 3000rpm upwards, again with tacho needle flicking. I can even ride for 20 miles gently and all seems fine if i stay below 6000rpm, but the first time I give it more gas or go over 6000-ish rpm, it reappears. Not only that, but i then have the bike stuttering/misfiring at any rpm or throttle load for a few miles, although not constantly. Also, constant load at 90mph-ish, ie 6000rpm is sometimes fine and at other times it stutters. Everything to me seems to point to an ignition coil breaking down, but what do you think?

Hinckley · 05-17-2005, 06:10 PM

I'm assuming you are refering to a T3 900. If so, my first thought would be coil wires. Are they loose, cracked, etc.?
Or.... It could be the coil itself as you mentioned...

Skidpan · 05-18-2005, 04:26 PM

Yep, its a T3-900. Coil wires seem ok - I was testing them as my wife said "you have a reply" so I will go and test again. Is there a static test for a coil that puts it under high load as if revving that i can do on the workbench?

Skidpan · 05-25-2005, 05:53 PM

I have just been told by a Triumph mechanic that this misfire with tacho 'blip' is caused by number 3 coil breaking down under load. I am being lent a coil by him to try. Will let you know the result as and when.

Skidpan · 06-27-2005, 05:25 PM

Finally, weeks later, I've got a new coil. Replaced no.3 coil with it, and changed no.3 spark plug whilst I was there. RESULT!!!!!!!!!!!!!! Misfire gone, bike perfect. Huzzah!!!!!!!

Skidpan · 07-12-2005, 05:26 PM

600 miles later, it cut out altogether 3 times in 5 miles as if the kill switch had been hit. Started up ok each time and got it home. Checked under the seat and one of the battery terminals was corroded,cleaned them up and then it was fine. Yesterday, 300 miles later, the misfire returned, complete with tacho flickering just like before, all the time for 25 miles. B'LLCKS. Got home last night, took the seat off, did'nt have time to do much so just pinched up the battery terminals, even though they appeared clean and tight. Done 60 miles today and it never missed a single beat. I wonder, was the original misfire not the coil but a loose/dirty battery connection???? I know when I replaced the coil, I did things like nip up the battery terminals, so maybe doing that fixed it and replacing the coil wasn;t the problem. If anything changes I'll update this thread - it baffles me to a degree but it might help one of you....