Air flow for a 25 mm carb

[Hammerite]

Will a 25 mm phbl breathe through a series 2 airbox well enough as the neck is narrow ?
If not , will a series 3 airbox slot straight in ?
Thanks

[HxPaul]

I have a 1960 series 2 and I was told that the top toolbox fastener would catch on a series 3 airbox,stopping it from fitting.I had a series 3 airbox so I tried it and it fit........only just,but only just is just enough.

[Tractorman]

I drill some 1/2inch holes in the series 2 air box and had no problems with air flow.

[rainbowrunner]

I have a 25 delorto on my series 2 running through the airbox, its the wide necked one with no extra holes, changed the air scoop for a bigger flow , runs flawless with my RT195 kit

[Hammerite]

Do you know what the jetting is for your 195 set up ?

[rainbowrunner]

no sorry, H Bomb scooters fitted the kit & carb