Sourcing of Spares for Villiers Mk 25 Engine

Having got over the excitement of unceasing our Villiers Mk 25 engine over the weekend I have tried to source replacement parts and have several questions.

1. The steel fuel pipe routed from the fuel isolation tap at the bottom of the tank to the CM358 carb has corroded and is in 2 bits. Searching the internet, the only thing that comes close is supplied by L&S spares and only claims to fit Mk 25s fitted with Zenith carburettors.

Does anyone have a source for the fuel pipe or am I into the realms of making one myself?

I have put a query into L&S spares but have yet to receive a reply.

2. On taking off the head I noticed that the previous user had fitted the incorrect spark plug. The remains of the spark plug I removed was the shorter threaded type and not a KLG ML50 or recognised alternative.

I’ve tried to source the KLG ML50 from Villiers and other places to find they are out of stock. I have also tried to find an NGK equivalent, but any listings of the NGK plugs do not list the KLG ML50.

What spark plug would members recommend as a replacement for the KLG ML50?

3. On removing the above spark plug there is significant evidence of dissimilar metal corrosion between the head and the spark plug threads which makes the head unusable in its current condition as the integrity of the threads have been compromised. My research on the subject suggests that the way forward is to buy a new head or get a helicoil fitted.

a. I’ve located a new head on the Climbers and Cutters website at £24 but there is something about the website that makes me uneasy. EG There are no images of the items they claim to sell. Does anyone have any thoughts on this company?

b. Alternatively, does getting a heli-coil fitted mean I would be looking for a different spark plug to the ML50 or equivalent because the spark plug hole will be narrower?

Help with the above would be most appreciated.

Tony

Unless you are a bothered about total originality, I would just replace the fuel pipe with a piece of hose, I assume there is enough good pipe either end to fit a hose to?

Couple of alternative plugs listed here: https://www.gsparkplug.com/1x-klg-spark-plugs-ml50-eqv-lodge-cb3-champion-7coml.html

Secondhand heads turn up on ebay from time to time. Not sure whereabouts you are, I've got an almost complete MK25 HS sitting here you could have for £1 more than the cost of that new head...

Thanks for your response Matt. I live near Thirsk. Thanks for the info on alternative spark plugs. It's much appreciated. I had considered replacing the corroded pipe with a rubber alternative but noted that the 'original' pipe had a bend in it that seemed to intentionally bent around the engine block as if it was designed to prevent the fuel pipe over heating causing fuel starvation problems. I'm not sure that there is enough pipe on the fuel tank end. It seems that water/condensation had run around the fuel tank to very bottom of the tank then dripped onto the pipe resulting in it rusting just behind the pipe solder joint. I may just buy the fuel tank end and repair the pipe with rubber tube from there.

As for the Mk25 HS I'm not clear what the HS stands for I'm guessing its 'head section'. If it will help solve the head spark plug thread issue I will be very interested. Happy to pay the price suggested plus P&P of course.

Tony

'HS' stands for 'High speed', it's a version of the engine with a Zenith carb and a higher governed speed than the standard version. The price would be for the almost complete engine as pictured.

Following on from @mattblack

Manual shows that fuel pipe should be flexible hose with nut and olive at tap end and banjo bolt at the other. If you have an HS then it should be Zenith 24T-2 carb - maybe you have a 'pick-and -mix'
Try BB Engineering Supplies or vintage motorbike supplier for connectors.

Helicoil sounds OK if the head is in other wise good condition. A local engine shop should be reasonable if you don't want to go the expense of buying the kit.  But, as Matt says MK20/25 heads turn up regularly on ebay or a member may have one.
I'd be very tempted to take up Matt's offer.

PS Have manual if you need one.

I ordered a manual for the engine over the last weekend and its due delivery tomorrow. Even if I don't use it to solve my immediate issue I'm sure it will make interesting reading. I'm learning that quoting Part Numbers when conversing about spares is the way forward so the manual will be a starting point. Realistically I should have realised this from working in the aviation industry but didn't appreciate its importance on machinery this old.

I am going down to Thirsk later today. I have a friend who has just recently retired from agricultural engineering to see if he has kept any of his tools (Helicoil kit). Regardless of the outcome I am interested in Matt's offer even if the helicoil solution works. I just need to figure out the logistics element.

As for the fuel pipe thanks on your clarification of what should be fitted. I definitely have the CM358 carb fitted on this engine. With my extremely limited knowledge on the subject (checking the name plate) the engine is a 'standard Mk 25' rather than the HS version. Although I'm happy to concede I may have a mix and match engine.

I rechecked the damaged pipe this morning. As a result I ordered a flexible pipe with the banjo connection and what looked to be the correct connection on the fuel tank end from L&S so I'm confident there's a fix in there somewhere. Initially I may have been misguided by the fact that the L&S website said their product only fitted Zenith Carbs.

If nothing else this project is stretching the brain cells

My thanks to you all for the help so far.