I thought it would be a good idea to keep you good folks updated on progress.

I've machined a 100mm long properly fitting Spring guide from 316 stainless and polished it up so that job's done.

I've cut and fitted a 0.25mm piston sleeve and slip washer to the piston which has brought it's weight upto 249 grams.

I'm aiming to end up at about 270 - 280 grams and I'll now be going for a slightly heavier piston nose and just a 1mm stroke increase for a good reason.
I'll be using a BSA Mercury sized O ring with a 3.175mm cross section for the piston seal and I'd like to keep 2mm of piston head either side of it so I'll end up with a 7.175mm wide piston head --- say 7.5 allowing for groove clearance.
The leather piston head was 8.5mm wide so at 7.5mm wide for the new O ring piston head I'll be gaining just 1mm of stroke taking it upto a 70mm stroke.
I've calculated that the new piston head will weigh in at 25grams compared to the leather sealed piston head's weight of 6grams so fitting this will take the overall piston weight upto 268grams (249+19).


As a bit of bonus good news, I originally wrote on this thread that the transfer port was 26mm long as that is what someone had posted on here --- this isn't true.
My LG35 has an overall transfer port length to the cylinder of 19.2mm with 17mm of that length at 4mm ID the other 2.2mm is a little domed collection chamber in the centre of the cylinder.
I can only assume the chap who measured the transfer port at 26mm had his vernier slip into the Allen key hole in the front of the piston when he measured it ?

So now I'm aiming at :-

A swept volume of 43.12cc (28mm bore X 70mm stroke)

A transfer port volume of 0.105cc (sleeved down to 2.8mm X 17mm)

A static compression ratio of about 410:1 --- I can't work this out exactly due to not knowing the collection chamber volume.

And an all up piston weight so about 275grams --- I'm allowing some for a Delrin top hat.





All the best Mick