Airsporter MK1 Cylinder ID

[T 20]

Hi Folks

I'm just working on an Airsporter MK1 and the cylinder appears to be 1.088" ID and not the normal 1.125" ID has anybody else found this ?

I only found out when I tried to fit an Airsporter MK2 piston and found out it was too big.


Weird



All the best Mick

[dogsbody]

Could it be a Club cylinder? The early .177 Airsporter not a .22 cylinder.
atb
dogsbody

[T 20]

Could it be a Club cylinder? The early .177 Airsporter not a .22 cylinder.
atb
dogsbody

Hi dogsbody

It's a .22" Airsporter MK1.

I thought the Club had a shorter cylinder not a smaller cylinder ID ?


All the best Mick

[dogsbody]

Hi Mick,
Quite right of course, according to J. Knibbs, the Airsporter cylinder was 5/8 inch longer than the Club, increasing the stroke from 2.4 ins to 2.8 ins.
I have been up to my shed and have been doing some measuring.
Pistons for Mark I, II and V Airsporters measure 1.08- 1.09 inches measured at rear.
o/d cylinder diameters for Mark II and V Airsporters and Club measure 1.25 inches
i/d cylinder diameters for Mark II and V Airsporters and Club measure 1.14 inches measured at end of cylinder before threads.
If the head has the conversion for an O ring, is it made of PTFE(?)?
I think this is capable of swelling and becoming oversize. I had to replace the piston head on my Mark V when I stripped it down as no way would it go back in. It was in bits for over 6 months though.
Hope this helps,
atb
dogsbody

[T 20]

Hi Mick,
Quite right of course, according to J. Knibbs, the Airsporter cylinder was 5/8 inch longer than the Club, increasing the stroke from 2.4 ins to 2.8 ins.
I have been up to my shed and have been doing some measuring.
Pistons for Mark I, II and V Airsporters measure 1.08- 1.09 inches measured at rear.
o/d cylinder diameters for Mark II and V Airsporters and Club measure 1.25 inches
i/d cylinder diameters for Mark II and V Airsporters and Club measure 1.14 inches measured at end of cylinder before threads.
If the head has the conversion for an O ring, is it made of PTFE(?)?
I think this is capable of swelling and becoming oversize. I had to replace the piston head on my Mark V when I stripped it down as no way would it go back in. It was in bits for over 6 months though.
Hope this helps,
atb
dogsbody

Hi Dogsbody

Thanks for the measurements which kind of confirms what I found in that the MK1 Airsporter has a smaller ID cylinders than the rest.

All other Mercuries and Airsporters have a cylinder ID of 1 1/8" ( 1.125") but the MK1 I've just been playing with has a 1.088" ID.

The genuine BSA O ring conversion for my Airporter MK2 which I fitted in 1973 looks like it's made out of Nylon. The conversions sold by Chambers are made of Nyloil but look to be very close to the BSA item.

Anyway it doesn't really matter now as I've made an O ring piston head from brass for the MK1 I'm working on.

Like this

http://i1138.photobucket.com/albums/...3012006146.jpg

Top Webley MK3
Middle genuine BSA Airsporter MK2 conversion
Bottom brass O ring head on MK1 piston


The MK1 belongs to an 80 year old chap who has owned the gun from new, he brought the gun to me for an ovehaul.
The gun has been apart and back together a couple of times this week but it was a bit inconsistent with the leather seal ( 60fps spread) so I decided to bin the leather and go with an O ring.


All the best Mick