Scooterotica

It could be detonation.
Detonation can break the porcelain on the plug and also cause premature bearing failure. (from what ive read)
You did say it was "eating plugs" ? in what way? and why did you suspect detonation in the first place?
If the engine has never been apart, it could be a piece of the plug, rattled around for a bit and exited down the exhaust port. The owner would`t know much about it ! he might of just changed the plug and carried on ?
Russ

I've found what looks like pieces of piston ring embedded in the piston crown , i'm contacting chiselspeed tomorrow to see if they build these with thrust washers on the crank or not and I'll have the crank out to rule out washer disintegration or seal plate screw heads damaged. The investigation goes on..

carlos fandango wrote:It could be detonation.
Detonation can break the porcelain on the plug and also cause premature bearing failure. (from what ive read)
You did say it was "eating plugs" ? in what way? and why did you suspect detonation in the first place?
If the engine has never been apart, it could be a piece of the plug, rattled around for a bit and exited down the exhaust port. The owner would`t know much about it ! he might of just changed the plug and carried on ?
Russ

Hi Russ it was just failing plugs not actually damaging them as far as i know.

Cheers

Jay

2nd picture down - top middle of pic there looks like a piece of metal sitting proud of the surface. could this be , or be part of the foreign matter that has been crushed between the piston crown and head?

mickdale wrote:2nd picture down - top middle of pic there looks like a piece of metal sitting proud of the surface. could this be , or be part of the foreign matter that has been crushed between the piston crown and head?

Yes mick your right, Ive dug it out and it looks like a piece of ring, but i will have the crank out tonight just to eliminate the other possible causes. Chiselspeed isn't open until tomorrow so will call them then to ask about thrust washers..

check for any damage to port edges esp uppermost exhaust ... and also make sure pegs aren't recessed too much that the rings can ride over the peg. If its chewed up and spat a ring out, you need to try and find out why. Whats the exhaust port width?

soullad wrote:check for any damage to port edges esp uppermost exhaust ... and also make sure pegs aren't recessed too much that the rings can ride over the peg. If its chewed up and spat a ring out, you need to try and find out why. Whats the exhaust port width?

ok will check them out later.

Thanks

Jay

Question ? tuners tend to mark barrels with a code or signature, would a tuner also mark the head as a pair??

So lets say it has : 0001 touring on the barrel, would you expect to see this on the head?


Ta Jay

Frautzi wrote:

soullad wrote: Whats the exhaust port width?

ok will check them out later.

Thanks

Jay

soullad.. i measured the exhaust port by putting a piece of card in the barrel shaped it to the barrel and marked the widest point of the port . the widest point is 50mm??

jay

If you have measured the port "as said" but then flattened out the card and measured (now flat) then this is a safe width...
IMO