Converting a Villiers Mk20 to Mk25

Hi all,

Is it possible to put a mk 25 top half to a mk 20 bottom half, as I have a good bottom ( wait for it ) half on a Mk 20 and a good top ( now now ) half to a Mk25
I think I am right in saying that the only difference between them is the bore size.

go for it it does what i said on here year them ths back and ive done 4-5 of them this way for customers for none rally use, as they a classed as a bitza engine
p.s just watch your valve shimming on rebuild thats it really
kev

Good point about the valve shims Kev. I thought my valve stems had shrunk until I realised that I'd forgotten to re-shim. By the way, I presume modern motorbike under bucket shims would be a suitable alternative. Anyone ever tried ?

It just happened that I had to re cut the valve seats, lucky for me found a valve seat cutter in the garage, wondered if I would ever have to use it and only had to use 3 shims from the mark 20 to get correct gaps.
Had it running this afternoon all good, timing too, good when you know how to do it properly.
I like the mk 20 and 25 nice to work on everything is just that much bigger, I have an eye on a mk 25 with a 110 vault generator
on it, hoping to get it next week, what is good about it is its all complete.

I had a mk 25hs 240v 3.5kva gen set great for rallys as could charge caravan and car batterys kettle and microwave lunch or dinner all at the same time, downfall took 3 people to get it in and out caravan and supt 1/2 a tank in 3o mins lol,but did also work my welder on the field for a guys trailer and 8mnths later he offered me good money for it so off she went to a good new home, now mounted in a locker under his campervan and exhust piped into main engine system so should be much quiter when i get to see it this season
kev

Woodsman wrote:Good point about the valve shims Kev. I thought my valve stems had shrunk until I realised that I'd forgotten to re-shim. By the way, I presume modern motorbike under bucket shims would be a suitable alternative. Anyone ever tried ?

hi woodsman
thats were they are on the villiers engines under the pushrod caps/buckets before the valve stems
thanks kev