What I did with my classic Triumph today?

Hi,

pidjones said:

petcock leaks
drained the tank and applied heavy Teflon tape to the threads. The, re-installed with new "Dowty" washers

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Real "Dowty washers" (aka "bonded washers"):-

... aren't correct for sealing fuel taps to Britbike tanks.

Correct are Stat-O-Seal:-

... the differences are:-

. Stat-O-Seal seal is much thicker than the metal retainer around it; installed with a plain washer between Stat-O-Seal and tap locknut (to prevent the locknut ripping the seal), the Stat-O-Seal's seal is prevented from expanding in three of four directions when the tap locknut is tightened, correct 1/4"BSP-size seal can only expand into a small area of the tap's thread, sealing it without any need for additional sealing such as Teflon tape.

. Otoh, real Dowty seal is barely thicker than the metal retainer around it; moreover, the seal has a "C" cross-section, designed so that pressure within the "C" presses its ends against the surfaces above and below the washer to seal; however, fuel in the tank leaking down the tap threads does not generate sufficient pressure within the "C" to press the ends against tank and nut to effect a seal.

. If 70-7351 is ordered, you should be supplied a 1/4"BSP (0.518" ID, 7/8" OD) Stat-O-Seal (although I notice L.P. Williams sadly show an incorrect Dowty ), If 83-0002 is also ordered, you should be supplied a plated plain steel washer with matching ID and OD.

. Otoh, a real Dowty with even the correct 1/4"BSP ID will have a much smaller OD (see top image in this post)

Another advantage of the correct Stat-O-Seal is the thickness of the seal prevents the edge of the metal retainer contacting the tank (unless Guy The Gorilla's big brother tightens the tap locknut ), no chance of the retainer scratching tank paint. No such advantage using real Dowty washer.

Only possible fly in the ointment in the US is @TR7RVMan Don has posted previously that even alleged 1/4"BSP Stat-O-Seals available in the US do not seal well; the ones available in GB do ime.

Hth.

Regards,

I used fuel-resistant tape designed for gas (petrol not listed) fittings. Had some left from building a gas handling rig for use at CERN. One of the gases was helium - notorious for both leaking and diffusing, and another was xenon - rather expensive in the purity needed. It was to be used in an inaccessible high-radiation area, so had to be leak-tight and fail safe. Because dismantling and re-arranging might be required, I made it without welded/brazed joints and as simple for my researchers as possible with no disposable seals other than a few o-rings. So, it had many NPT joints. I found this tape excellent for building it leak-tight, and sent several spools of tape with it to CERN, just in-case. The physicists reported that it worked trouble-free. I have since used my own spool of that tape (the tape is pale yellow and the spool bright yellow) for several projects. I prefer "pipe dope" on water systems, but didn't think that was appropriate here. The tape (you MUST use caution not to over-tighten joints when using it!) Combined with new Dowty washers appear to be working fine. Overnight test shows no staining on the paper towels wedged under the petcocks.

Winter not quite done with us yet here in the UK, but yesterday was warm and sunny, so out came
the 72 Daytona.


Third trip of the season. First trip was a month ago - a simple 3 mile pootle around the lanes to be sure it all worked. Then a short 10 miler a few days later which included a 60mph blast along a couple of miles of A road - which is where it went wrong.

After a couple of minutes at 60, it started to cough, and after a minute or so it died altogether. Electrics seemed fine, it had petrol, and after tickling the carbs it fired right up - but still a bit uncertainly - so made a bee-line for home and put it away for another day. Checking the fuel system a few days later revealed a few teaspoonfuls of water in the float bowls. The bike was put away OK in November in my warm garage, running the carbs dry, and I drained the tank.

Filled with fresh 99 E5 octane before I started it for the first time, all seemed fine. So where did the water come from? The E5 petrol presumably and it would have had to have been in the float bowls for some time. I assume that the high speed running drew the water up the main jet.

Anyway, lesson learned maybe and I treated the third ride cautiously, but almost 50 miles later the Daytona had run perfectly, never missing a beat. Stopped for coffee and cake at a new farm shop nearby, risking a hot start. Whilst I'm not usually bothered by a hot start, I had a difficult one last year and it's made me more wary. I thought I'd got hot starting the Daytona cracked, but maybe not.

This time I elected to tickle one carb only, no choke, and it started first kick. Maybe tickling both carbs and using the choke simply flooded the engine when I had a difficult start. Need to find a reliable way of priming a hot engine - but at least this time it worked, but it was a cold day compared to the hot day last summer with the difficult start.

My 73 Tiger 750 is off the road atm having a sloppy-fitting rear wheel bearing fixed so I have the Daytona to ride more often. It's not the most relaxing of rides but it does go well when I boot it!

Hi Andy,
My guess is on this timeline of events.
The E5 contains alcohol, this draws water from the atmosphere.
After a few months the light alcohol has evaporated and the water drops out to the bottom of the tank. (Luckily it has not rusted through).
On your first ride it has taken a while for the water to make its way through your petrol taps to the carbs where it settles at the lowest point, which just happens to be under the main jet.
Plodding around on pilot and needle jet did not produce enough flow to lift the water into the main jet, but when you cracked open the throttle the water lifted and shut off the main jet. When you back off the water drops back and unblocks the main jet again, so you are able to gently ride home.

E5 is a bad dream, E 10 is a nightmare-avoid if possible.

Regards
Peg.

Rancidpegwoman said:

Hi Andy,
My guess is on this timeline of events.
The E5 contains alcohol, this draws water from the atmosphere.
After a few months the light alcohol has evaporated and the water drops out to the bottom of the tank. (Luckily it has not rusted through).
On your first ride it has taken a while for the water to make its way through your petrol taps to the carbs where it settles at the lowest point, which just happens to be under the main jet.
Plodding around on pilot and needle jet did not produce enough flow to lift the water into the main jet, but when you cracked open the throttle the water lifted and shut off the main jet. When you back off the water drops back and unblocks the main jet again, so you are able to gently ride home.

E5 is a bad dream, E 10 is a nightmare-avoid if possible.

Regards
Peg.

Click to expand...

Hi Peg,

I think you are right - but it was fresh petrol in the tank and the tank was stored empty in my warm garage over the winter months. I didn't drain - or I don't remember draining - the float bowls when I put it away in October - but I normally do. So I think the water was from last year's fillings and the water accumulated in the float bowls and I didn't drain them when I put the bike away. Think the object lesson is to drain the float bowls occasionally to be sure there's no water in the bottom.
And yes, it was my conclusion that pootling around as I usually do on part throttles never drew up the water into the main jets. It was only when I had to keep up with modern A road traffic that the main jets came into use.
I also seem to acquire some lumpy running on my Tiger 750 at A road speeds towards the end of last summer - and I bet that's the same cause. Will be checking that shortly! That bike I run on E10 as it has 7.4:1 CR pistons and of course a single Amal Premier. But it may well be more susceptible to water accumulation.

Both of my classic Triumph tanks are lined with Caswell epoxy so I'm not unduly worried about leaving petrol in over the winter - but I do usually drain the tanks anyway.

Hmmmmm...... Water in E5 petrol, again. Out on the Daytona. 40 odd miles, including some fast running, never missed a beat. Then, a few miles from home, A road, 55mph, a cough. A couple of miles from home, fastish, not pootling, more coughs. Then a big cough and a backfire and it died about half a mile from home. Hmmmmm.

Tickled both carbs, kicked it, nothing, nothing. Then it fired up as though nothing was amiss. Hopped on and rode home without further ado.

Let it cool off for a couple of hours then emptied both float bowls. The petrol looked cloudy, and after sitting for a few minutes there are definite blobs of water in the container. Not much, maybe a dozen or so large pin head sized.

The petrol in the tank was maybe 50% bought last week and 50% a month old. I buy my E5 in a 5 litre can when I go to fill up either my car or my Hinckley Bonnie. The can then sits outside (safer than in my house!), and it can get rained on - but I fail to see how rain gets into a tightly sealed plastic petrol can. I'm wondering, since I think both lots of E5 came from the same garage - a small to medium sized facility in a nearby village - if they have water in their E5 fuel tanks.

Whatever, the way I buy or store fuel seems to be an issue.

for a variety of reasons my T140 spends the winter in a garage a long way from where I now live. So Saturday afternoon was a Scrambler ride to London via Elgar country, the Cotswolds & Chilterns. T140 serviced Saturday evening and Sunday morning, a quick local ride to check all was well, then a nice 150 mile ride back home to Radnorshire. Bike running very nicely after being a bugger to start initially.

The Motobatt died over the winter (after ~10 years, so I'm not complaining too much) - it lasted a lot longer than the last Yuasa batteries I have used. 'Borrowed' the battery out of my other bike for the sake of getting going.

Found some old disc brake pads and put them side by side with the thought of photographing them to illustrate different pad sizes for the brake service thread, but then forgot in my rush to get on the road.

I'm hoping to get out and about at the end of April for the VMCC Founders relay rally.