LCGB Forums

Hi John

Piston, smooth but scored.

mmmm its a difficult call Chris I'd want to know why it failed in the first place. Have you checked that all the cylinder ports have a slight bevel and been smoothed off around the edges ?

The problem is that if you don't remove all the scores and scuffs there will be a tendancy for carbon to build up on the wall of the piston which could potentially lead to seizing if the engine overheats or you run it flat out with a lean mix or certain oil types . Saying that it can and does happen with brand new pistons too.

Then again if there is plenty of clearance between the piston and bore and the piston has been run in previously the chances are good that it will run fine and with new standard rings fitted will give plenty of compression. To be sure you really need to be able to measure the piston and bore accurately after cleaning and dressing the piston scuffing and scoring.

If you can afford £30 or so for a new piston set (which includes rings and pin ) I'd recommend fitting that because new rings alone will probably cost you half that .
Whatever you do measure the rings and piston in the bore for correct tolerances.

if it were me I'd just give the piston a polish the cylinder a light hone and refit it it with the original rings and give it a go but I just pootle about hacking around the countryside so perforance is no big deal to me.

Thanks John.

Ive got new rings and will hone the vylinder. Its worth a go as you say. If doesnt work? I will get a new piston.

Thanks again.