Repair your fuel tap

Don’t put up with leaks… service that fuel tap

Many Japanese and Italian fuel taps were similar; we look at how to rebuild them

When the Japanese factories finally got to grips with making commercially viable motorcycles, they rapidly standardised the small but vitally significant components that can make or break owner satisfaction.

One such item was the humble fuel tap and for once the device wasn’t a rework of an existing design, it was a completely fresh take on the concept. Careful to avoid tapered holes, springs or corks, the major players all opted for variations on the theme of a rotating lever carefully channelling petrol through just two chosen drillings.

Key to the set-up were fuel resistant synthetic rubber gaskets, precision aluminium castings, along with connections to the petrol tank that were impervious to both fuel and vibration. Until the advent of fuel injection, the basic design of the humble Japanese fuel tap varied little, other than vacuumoperated taps – and even they worked in a similar way.

What follows is an overview of the refurbishment of a typical Oriental fuel tap that fits to the Canadian market Yamaha CS3C currently occupying space on my bike bench (it’s also the same as my Honda CL350 – Ed). This particular unit fits to the tank via a spigot and nut, but its construction and operation are essentially the same as those taps that fit to the tank via a pair of screws or bolts.

Given the state of the tap we’ll be starting off by breaking it down into subassemblies, looking at what’s there before cleaning it and looking at what might be needed to get it back up and serviceable.

In our opening shot we have two taps from period Yamahas; we’ll be working with the one on the left but the overhaul process is identical for both, save for their union with the fuel tanks.

1: Broken down we can see the main tap body with its spigot union above. To the right we have the constituent components of the operating mechanism then below are the lower filter, bowl sealing gasket and drain bowl.

7: Something to be aware of – the brass filter tube for the reserve supply has broken free of its base… but we have a plan.

10: Result! Yamaha still list all the parts needed to rebuild the tap. How good was that? And better still the parts were less than most folk are charging on eBay for decades-old NOS!

You’ll find plenty of pattern fuel taps out there for sale and often at what appears to be good money – but a word of warning. Unless you know of someone who has similar it might pay to avoid so-called ‘bargain price replica taps’. Numerous examples have failed in fairly short order and generally due to poor quality seals that are very prone to breaking down in modern petrol. If OEM seals are still available buy them and preferably, if you’ll be keeping the bike, acquire a few as spares. If OEM isn’t viable and the likes of eBay don’t have what you need, then replica taps from decent sources is a good Plan B. If you buy from trusted names with a track record then you should be sorted. Just remember – modern pump fuel is remarkably good at attacking most motorcycle paint finishes – a tenner saved on cheap tap or service parts is a false economy set against the cost of repainting a tank or a crankcase cover!

2: Clearly the tap has never been off the bike as evidenced by this vile crud sitting in a blind casting. It’s time to call in the big guns. 3. After a severe talking to by my indispensable ultrasonic tank, a fair proportion of the old fuel deposits have been removed. This allows a closer and more thorough examination of what’s on the bench. 4: As might be expected after decades at the mercy of stale fuel, some of the gaskets are the worse for their experiences. It’s time to study the parts books and ascertain what is still available from Yamaha. 5: Ultrasonics can only go so far and what’s in the base of the filer bowl is strongly bonded to it.

6: Dremel to the rescue! The brass bristles of the brush are strong enough to evict this amalgam of rust and old fuel, yet sufficiently gentle not to damage the soft alloy casting.

8 & 9: It might look weird but it works amazingly well. Harpic Power Plus shifts corrosion from cast alloys and brass in an effective yet controlled manner. Simply brush on and agitate, then rinse off well with hot water… job done!

The new fibre washer replaces the crumbling rubber one and a few minutes with some brass mesh and a soldering iron has a new reserve filter installed in place of the broken one.

11: Buying new, replacement, parts from dealers can sometimes mean you will receive a revised or updated component that doesn’t look the same. There’s generally no need to panic as the up-issued part is normally better quality than the one it replaces.

The lower filter is still partially blocked but a soak in some paint thinners and careful cleaning with a brush will have it sorted. With the main tap seal/gasket back in place all that’s needed is the final assembly. The wave washer sits on the outer face of the tap lever and is held in place by the oval tap position plate and two small screws. If, after fitting, the lever feels unduly free remove the waver washer and very carefully tweak it to increase pressure on the tap lever. One rebuilt tap ready for use and only one more to sort out.