melted coil stick

[Kevint]

Thought I would show what I discovered whilst hunting for the gremlin causing my surging at around 3-4000 revs.

https://www.dropbox.com/s/m6nohixw227m1ez/coil3.jpg
https://www.dropbox.com/s/36jz4yyxfsj72x7/coil3a.jpg
https://www.dropbox.com/s/jnrv0zmnqkr0266/coil3b.jpg
https://www.dropbox.com/s/58po03w2x1mzchd/spark1.jpg
https://www.dropbox.com/s/s1c0dec5ooh4ymo/spark2.jpg
https://www.dropbox.com/s/vxirfcguz6ahys9/spark3.jpg
https://www.dropbox.com/s/y69fz6x8ufk4dyy/spark%204.jpg

I have also uploaded a photo of each spark plug. The 2 lean plugs were the top plugs and the two blacken plugs were the bottom plugs. Presume, they still look ok and wont have been destroyed by my faulty coil pack?

[Steptoe]

Blackened lower plugs is normal on a twin spark engine.

And coil caps melting happens when they've been failed for a long period of time, i've even seen them catch fire and burn the cap wiring, that's why there's a purpose section of wiring available from bmw to repair those that do get burnt.

[Kevint]

Thanks steptoe. Seems like I discovered mine on the knick off time!

What's the easiest way to test them? Presume using a spare spark plug and starting the bike would do it as I could then look for a spark?

[RiceBurner]

I'd suggest that when you get the new ones, you coat them in high-temp resistant grease (silicon grease) before you re-install them.

My theory is that the plug caps aren't really designed or optimised for being 'outside' (as opposed to under the bonnet of a car) and their waterproofing can be easily compromised. Every plug coil I've seen fail has had evidence of internal corrosion.

Anyway - since I started coating the coil caps I've had no troubles with them whatsover.

It might also help that the newer coil caps are possibly better made (the grey ones).