my top piston has committed hari kari!!
lost compression on it , so looked up the port and the top front of the piston is missing above the rings.
it hasn't seized so i'm hoping cylinder damage is minimal!
got most of the bike apart tonight just gotta prize the cylinder off to have a proper look tomorrow!!
everyboby say a prayer for me !! lol

whats the likely cause? thought it might be blown head gasket damage??

dunk

Detonation?
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

soooo as i understand it this is the result of pre-ignition caused by overly high temperature and pressure (?) in the combustion chamber.

What sort of tune/parts are you running on your bike Dunc?
_________________
After years of moaning about immigrants now i am one...

it's standard well apart from the wire splice and a few holes in the air box.
think the fuel line became blocked with crap and caused it to run lean on the rear cyclinder, on the plus side the front cylinder which was forever running rich had a lovely brown plug in it!!! sods law!

anyone got an mc18 r5k cylinder and head they'd like to swop for cash??
thought i'd ask before i have to send the broken ones away to be repaired.

And could any one recomend somewhere to send the cylinder and head???

http://www.langcourt.com/

Be sure to get the new piston first and send it away with the barrel so they can plate the barrel to suit.
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

that's weird as i was just looking at their web site.
do you know if they do heads as well dave as somethings been bouncing around in there making a right mess?
and do you have any idea how much they charge??
cheers.

Replate is about £100. Dunno about heads, not sure I'd trust a welded up one - can you get hold of a replacement one?
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Can you show us a photo of the damaged piston , then maybe we could help a bit more . I had a piston eaten away too , leaking head gasket . the head was warped and the top of the barrel !

Check the exhaust bridge for cracks
_________________
Why do things simply when you can complicate them

couldn't see any cracks, i'll post some pics up tomorrow.
managed to get hold of a new head fom david silver and will get a top end re build kit from Gav. just gotta get the cylinder re plated then!
just what i need before xmas! it's cutting into my stella fund! lol!

Dave Ett wrote: Dunno about heads, not sure I'd trust a welded up one - can you get hold of a replacement one?

Yeah, but it's more fun cleaning it up and seeing if you can get away with running it
_________________
Please do not PM me technical questions, if you can't find it on the Forum start a thread

think by the time i'd got it smooth i'd end up with a 300 kit! lol

I'd agree with you for a track bike Fontyyy, but for road use it's just a pain in the tits to have to pull it again.
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

On my 1st pass top end rebuild, one on the barrels had a cracked exhaust bridge when it was examined by Aptec. I believe they use ultrasonics or something clever like that. It was welded and replated, but failed again within a few hundred miles.
_________________
Why do things simply when you can complicate them

well i hope that's not gonna be the case as a new cylinder looks rather expensive! was quoted about £300.