Hi Llew,
The HK25, 30 H4 etc all use pretty much the same style carby that uses the exact same bowl.
One thing that must be considered with these earlier bowls with the drain trickler at the bottom is that they all leak as Mod Gadge has already suggested. Many people just remove them and place a small nut and bolt with a fibre washer on each side to stop leakage.
No need for hasty cash spending as one will turn up in no time.
Cheers,
BB.
