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Yes, me again with a soliloquy about my troublesome 175 Turismo's thirst for oil. Following tobydmv's advice I've stripped down the upper engine
and discovered a surprising amount of wear in the cylinder bore - a very pronounced ridge is visible mostly on the rear of the bore which, I imagine, causes the piston
to rock back and forward during its travel on the upwards stroke. Since the piston is marked 60.6 on its crown I guess I'm close to maximum oversize so
I was considering a resleeve job on the barrel. Before deciding on this, someone kindly offered me another barrel & piston which seem unworn. Only problem
is that my 4 head retaining bolts are a very loose fit in the 'new' cylinder's threaded holes - my bolts seem about 1mm too small in diameter. So I cannot use them as is ;fit rethread inserts into the cylinder holes to bring them down to the size of my bolts perhaps is the way to go ? Can anyone on this forum confirm this difference in dimensions and are there likely to be other different dimensions that I should be aware of encountering if I swap parts ? The parts I have been offered are reputedly from a 175 Turismo, like mine.
Happy Xmas to all my readers !

Jonjim

The King of Pistons in Italy should be able to supply you with a 62MM oversize piston.
http://www.thekingofpiston.com/
Your problem with the retaining bolts seems strange to me, they should be identical for all Turismo's.
Good luck
Thomas

Could it be a modified GT barrel? Or perhaps a Turismo barrel modified to fit GT (or later) cases.
The turism crankcase spigot is smaller, but otherwise they're fairly similar.

My Settebello racer had been taken out to 200cc with a Triumph Tiger Cub piston. I'll be rebuilding it with a Honda CB350 twin piston.