Fuel tap rebuild

My fuel tap on my 1994 Daytona refused to turn off - petrol poured out regardless of tap position. The tap has three positions - on, off and prime. On and off are supposed to be controlled by a vacuum operated diaphragm that pulls a valve open when the engine is running. Prime holds the valve open via a cam in the tap so is the only position that should let fuel out of the tap with the engine off.

I managed to break the plastic knob when I was removing it. I had the 1991 Trophy one so could use it for the time being. The plastic knob engages with the aluminium fuel selector casting through a flat cast into its circular recess. This flat was the part that broke on the 1994 plastic knob. The 1991 one has the flat 90 degrees from the 1994 version, meaning the visible pointer on the outside of the plastic knob does not point down for reserve, back for on and up for prime. Instead, it points forward for  reserve, down for on and back for prime. 

Rebuild kit from Sprint Manufacturing

Extracting tap from tank

 I got a tap rebuild kit for £24 from Sprint Manufacturing.  It includes two new springs (one to hold the diaphragm closed when the engine is off, one to keep the selector valve in tension so it returns from the prime position), four new screws, a diaphragm, a rotary oil seal and two shaped rubber grommets to seal the tap body against the tank.

The body of the tap is held on to the tank with two long M6 screws that pass through the selector housing and fuel filter housing to engage with captive nuts.

Fuel systems don't like grit so it's important to have somewhere clean to do the job. I have an old set of stainless steel camping pans for jobs like this.

Vent hole (indicated byscrewdriver
tip)  to allow diaphragm
to pull valve out when the
engine is running. 

Removing diaphragm housing,
diaphragm valve closing spring
visible in the centre of the picture

The diaphragm is housed in a chamber at the rear of the tap. The cover is retained by four M4 Philips screws. It is likely to pop off under the pressure of the larger of the two springs in the tap body - get ready to catch it when it goes. 

There is a vent hole at the bottom of the diaphragm chamber, behind the fuel selector mechanism. I think my problem was probably dirt ingress through this vent hole interferring with seating of the diaphragm valve. 

Aluminium plunger with o-ring
under diaphragm

Diaphragm valve seat location

The diaphragm is actually two diaphragm components that attach to an aluminium plunger with an O-ring at one end. The two diaphragms fit either side of a plastic collar. There is a hole in the diaphragm that locates over the vent hole - a raised bump in the plastic collar helps to make sure it is round the right way on reassembly. 

After pulling the diaphragm housing apart, it was very clear that dirt certainly could have been responsible for the problem. So a thorough clean was required. 

There were traces of corrosion in evidence too so it carefully (there's a word) rubbed the sealing surfaces back with wet and dry on a foam sanding block.

Cleaned and ready for reassembly

I used silicon grease sparingly on the sealing surfaces, eased the new diaphragm into its plastic collar then, checking that the vent holes were aligned, installed the new spring and tightened down the M4 screws. 

New (left) and old (right) diaphragms

Installing new diaphragm, making
sure the vent hole is aligned to the
matching hole in the new diaphragm

With retaining screws released, the
fuel selector is pushed up by the small
screw on the prime operating rod
and can be lifted out. 

The fuel selector is made of two parts, one an aluminium casting and the other a plastic component that it turns inside the top body. The aluminium part is held into the tap body by two screws. These screws have plain ends that fit into a track that is cast into the ally selector - they twist off centre to force the tap in when turned to the prime position. This is actually what makes prime work because a long steel rod pushes through the centre of the tap onto the diaphragm valve when this happens, thereby pushing it open.

Fuel selector pushed into place and retained by screws.
The fuel selector positions are cast into tap body - these make
sense with the 1991 tap but don't match up for the 1994 tap

Cylinder head cover: from grotty to gleaming

As I wrote in my second blog post, the paint dear old Ruby's engine covers had not faired well from being left outdoors. The cylinder head cover in particular looked like it had the mechanical equivalent of a severe skin problem.

A previous owner had made an attempt to tidy it up a bit with silver spray paint from the timing side but without removing it or the fairing - hence the overspray on a fairing infill panel.

Well anyway, that makes for an interesting challenge, thought I. With all those grooves it's bound to be tricky stripping it clean. So off it came.

I wasn't wrong - it needed three treatments with paint stripper and some Scotch abrasive pads. These pads are a plastic alternative to wire wool. I have found wire wool clogs quickly and rusts in paint stripper. They worked well - it was easy to swill the painty gunge out under a tap and then to rub some more. After a good hose down, I cleaned up some pitting on the embossed Triumph logo with wet-and-dry abrasive paper on a  rubber sanding block.

 Another hose down and then time for paint. I used VHT silver in approximately five light coats (left picture), followed with a two light and then one heavy coat of VHT clear (right picture below).

VHT is heat curing. I knew it would be ages before the bike would be ready for me to run the engine so I *carefully* suspended the cover from a hook in my garage ceiling and then heated it up a bit at a time with a hot air gun. This is a tricky business to do - too hot too fast and the paint will fail and flake off. It all worked out well. I'm very pleased with the finish I have achieved, as hopefully the photos show.

These pictures were taken at different stages of the other work I've been doing with the rest of the bike, especially to do with the swinging arm and rear suspension.

T300 CEV indicators

There's not too much to say about these indicators, other than that they are pretty well made by the CEV company. I had six all together: four from my Daytona and two from the Trophy. The Trophy had two odd replacements of unknown origin on the back. 

The indicators don't look sided at first glance but they are. There is small rectangular hole at the lower leading edge to allow water to drain out - if it gets in. All were pretty dirty inside so were treated to a nice warm bath. 

All were in reasonably good condition except one, which had a big crack down the side and showed lots of evidence of corrosion on the fasteners and also the flash-chromed reflector had crazed. Most had lost chroming around the edge where the amber lens bears down on them.

 I decided to use some Plastikote silver enamel paint (called 'chrome' but is more of a shiny silver) to seal the edges of all the reflectors, mainly to prevent the real chrome from being eroded further. I also painted the main surface of the reflectors that had suffered the most.

 I also coated the bulbs with an amber lacquer intended for fog lights, just because I'd had it for ages and thought, well, why not?