Gori 175 piston to bore clearance, should I worry?
Posted: Wed Mar 13, 2024 11:22 amHi,
My Gori 175 cast iron kit arrived today, looks nicely finished but I am a bit concerned about the piston to bore clearance - I know in Sticky's kit book the Gori 200 he tested had 0.13mm of clearance so maybe it's normal for these kits.
My rudimentary test of using 2x feeler gauges at the piston skirt with the piston at the top of the barrel gives me around 0.15mm of clearance, that is with the gauges pretty tight on either side of the piston.
0.15mm seems to be the wear limit on most standard Lambretta cast iron barrels, however in the Vespa world 0.14/15mm is clearance on assembly for most largeframes so perhaps Mr Gori has followed this rule?
The ring gap is approx 0.30mm.
I just wanted to check before I fitted it, grateful for any advice especially those who have already used this kit!
Cheers,
Rogscoot
My Gori 175 cast iron kit arrived today, looks nicely finished but I am a bit concerned about the piston to bore clearance - I know in Sticky's kit book the Gori 200 he tested had 0.13mm of clearance so maybe it's normal for these kits.
My rudimentary test of using 2x feeler gauges at the piston skirt with the piston at the top of the barrel gives me around 0.15mm of clearance, that is with the gauges pretty tight on either side of the piston.
0.15mm seems to be the wear limit on most standard Lambretta cast iron barrels, however in the Vespa world 0.14/15mm is clearance on assembly for most largeframes so perhaps Mr Gori has followed this rule?
The ring gap is approx 0.30mm.
I just wanted to check before I fitted it, grateful for any advice especially those who have already used this kit!
Cheers,
Rogscoot
but I'd personally buy an first oversize piston and get it rebored, or get the piston skirt coated with PC-9 or similar dry lubricant. The company that coats all my piston skirts can coat up to 0.1mm thick.