Re: Not a holed piston
Posted: Sat Jun 23, 2012 7:10 am
They have always had a good reputation from what I hear. Was thinking of building one a while back and still a possibility.
Bad luck Muttley . . . life's a bitch!
Sounds like you had the kit nice and loose and now it's a rebore and another few K till you get the new set up as good. I've seen this happen twice on Wellerchaps Mugello. Luckily, on both occasions the piston had started to melt and deform on the crown and was spotted when we took it apart to change the rings. Replaced the piston both times and all was ok. The mixture was spot on but was upjetted after the first problem and still did it again. Wellerchap did tend to hold WOT for vast distances like you.
I think part of the problem you've had is due to the very high quality of the piston in the GT kit, a cheapo piston may just have holed and let you off with a cheaper repair bill.
I'm now running cast iron (Harry Barlow 230) due to the cost of repairs when a nicasil kit lets go, but I do tend to have my left hand on the clutch when caning it. I still reckon a cast iron kit running on the clearance that "grown ups" reccomend will seize up if you cane it. I run 3.8 thou clearance on a 70mm barrel and have no trouble, bit noisier than one with the "correct" clearance but you can't have everything can you.