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post #1 of 11 (permalink) Old 04-07-2007, 04:16 PM Thread Starter
Grand Prix 500
Main Motorcycle: Daytona 900
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Join Date: Apr 2007
Location: Cambridge UK
Posts: 134
Hi All. This is my first post so be gentle.

Since I have now had to repair my petrol tap twice. I thought I would write up the procedure just in case anyone else is unlucky enough to have to do the same.

Symptoms of the fault.

1. Smell of petrol
2. Petrol dripping from air box
3. Pool of petrol on floor (bit of a give away really).

First things first, if you have a pool of petrol on your floor open all the doors to your garage then soak it up with something, sand is the ideal thing but some old rags will do. Once it is soaked up put whatever you have soaked it up into outside the garage then put some rag down to catch any that is dripping.

If you don't have a fire extinguisher go and get one, you never know it might save your bike and your life.

I recommend wearing gloves for this I use the PVC ones you can get from motor factors. Petrol is not good for your skin. Since I am extra sensitive to hydrocarbons I also use an activated charcoal face mask. (the type you use for paint spraying) If you have a stronger constitution you may be OK without but if you start to get a headache stop and go and get yourself a face mask.

Do not turn the bike on! Unlock the steering if you need to but be sure not to turn it to far, you risk a spark. (its fairly unlikely that just turning it on will cause a spark but why take the risk)

There are two basic failures on the petrol valve. One is that the membrane has split in which case cylinder three will be full of petrol. The second is the seal has failed in which case all cylinders will be full of fuel. (the second is what happened to me twice)

To sort the problem you are going to need to remover the petrol tank I am assuming you know how to do this normally. If the main seal has failed when you take the pipes off petrol will come poring out. So you will need something to bung the outlet with. I used some petrol pipe and clamped it at the other end with some cloth and a pair of mole grips (the cloth is to protect the pipe). (In my case I needed two since my bike is a Daytona and has two outlets). Be very carefully when you do this as you will end up with petrol pouring out whilst you try to put the sealing pipe on. I used some cloth to try to soak this up but it comes out quite fast so be warned and keep your face away from the pipe.

Once you have removed the tank put it safely to one side, hopefully it is not leaking petrol now. If it is try putting it on its side with the petrol valve up, so long as the tank is not very full you should be OK, if it is then unfortunately you are going to have to empty some of the tank until petrol doesn't leak past the main filler cap. you need to do this anyway so you can remove the petrol valve.

Now you should have made the bike mostly safe. Clean up any petrol that has spilt and remove the cloths from the area.

In the next stage you may need to remove the battery be very careful that there is no petrol near the terminals when you unscrew them as they will spark and could ignite the petrol.

The problem you now have is the air box, carbs and cylinder head are full of petrol. Bad news, you have to remove the carbs, there is no really easy way to do this its just a case of jiggling and pushing the rubber out of the way. (see your Haynes manual for how to do this) As the carbs come away from the engine expect petrol to leak out.

Once the carbs are clear place them upright on a piece of cloth, if you have a tray or something to drain the petrol out of them into this would be a good idea (if you don't you will just end up covered in petrol when you try to put them back in). Again expect petrol to leak out of them so if you can place them outside (out of the sun).

Now remove the air box. Place this to once side as it will need to be opened to clean the air filter.

Use a bit of rag to soak up as much of the petrol in the inlet manifold as you can. (dispose of the cloth)

Open the air box soak up any petrol with a rag. Remove the air filter, if it is anything like mine it will have petrol soaked into one side. I left it outside to dry off. Once it was dry I decided to clean it and found that washing up liquid made up into a strong solution removed all the grit grime and oil build up in the foam. Rinse it with plenty of clean water. I then squeezed the water out as much as possible and left it in the sun to dry (it must be completely dry before you put it back in)

Next problem. It is quite likely that petrol has got past the inlet valves and filled up the cylinders. This causes two problems - one you cant start the bike with the cylinders full of petrol and two it may have drained past the cylinder rings and into the oil. This is easy to test simply pull the dip stick walk outside with it (away from the smell of petrol) and see if the oil smells of petrol. If it does you are going to need to replace it. But do this latter. Check to see if the oil level is too high (because of the petrol in it) if it is you need to drain some of the oil now to prevent damage to the pistons and oil seals when we crank the engine over to remove the petrol from the cylinders.

Remove the spark plugs. (I find that using a 16mm socket on the end of the Triumph tool gives you enough extra length that you can do most of the turning using your fingers after you have loosened them using the Allen key.) Once you have removed the spark plugs disconnect the positive from each of the coils, you really don't want a spark whilst you are blowing the petrol out of the cylinders! Place a cloth over the top of the engine to soak up the petrol that is expelled. Reconnect the battery carefully.

Turn the engine over for a few seconds to blow the petrol out. Change the cloth if you need to. (remove the cloths and dispose of them outside)

Reassemble the air box and refit it to the bike.

Re fit the carbs - ( I opened mine up and cleaned the float bowls out whilst I had them off but this is up to you). I haven't found this as difficult as some people seem to but if you are having trouble the plastic slider method, where you use two pieces of thin plastic to cover the rubbers whilst you slide them into place, sounds like it would help.

Refit the spark plugs, and reconnect the coils.

Now it is time to try to fix the petrol valve. If your tank is very full you will need to drain about half of it off before you can remove the valve.

I bought a second hand valve from a breakers, this was a mistake. Either get a new one or get the refurb kit that I have seen on the web. (SprintManufacturing sell a kit) Once you either have a new valve or a reconditioned one refit it to the petrol tank.

Now don't make the mistake that I did - test it before you put it all back together. Fill the tank up with at least a couple of gallons of petrol - (this is why you don't empty it completely earlier)- support the tank level and make sure it doesn't leak any petrol, even a little drip is going to cause a problem (as I discovered). Put some cloth under the petrol tank valve over a tray if you have one. To fully test the valve I used the overflow pipe of the petrol tank and attached it to the vacuum port on the back of the petrol valve. Then suck gently, if you get the taste of petrol stop as the vacuum seal is leaking and you will end up with a mouth full of petrol. If not you should find that petrol starts to poor out of the valve. Stop sucking as soon as the petrol has flown enough that your sure it works. It should stop again almost immediately if not you may have a problem. I found I had to stretch the spring in mine a bit to get it to shut of quickly. (this was the second hand part, hopefully the recon part comes with a new spring ). Turn it to reserve and repeat the test. Last test, turn it to prime and make sure fuel runs out. Turn it back to on and make sure it stops.

Now you should be fairly confident to replace the fuel tank (don't forget the engine plastic spark plug covers, I always do).

So long as the oil wasn't very badly contaminated with petrol (i.e the level had only gone up slightly or not at all) then you can start it with the old oil to warm it up before changing it. I used engine flush to clean out all the contaminates but it probably wasn't really needed. If the oil is very contaminated i.e you had to drain some off, then change it before starting the bike just to be on the safe side. I changed the filter at the same time as quite allot of extra oil comes out when you do this.

Once you have changed the oil you should now be sorted. I would test start the bike before putting it all back together. If it all seems OK the refit all the panels.

If you are still a bit paranoid (I wish I had been) take the bike for a run, fill it right up so as there is the maximum pressure against the valve. The bring it home remove the side panels so you can access the petrol valve (you may need to remove the tank fixings as well ) then remove the two feeder pipes and see if any petrol leaks out. Obviously you will get a little bit when you remove the pipes so wipe this off then see if there are any further drips. If there are you have a problem as you need to drain the tank enough to remove the petrol valve again. Fortunately for me on the second time I did this there was no leaks. (up until now anyway the bike is sitting in the garage with the petrol pipes removed and I will check it again in a few Min's).

I hope this is of some help to others out there who hopefully will only have to do this once, unlike me who bough a duff valve second hand and ended up going through this whole procedure twice (so far). I hope the valve is now working properly but I think I will order one of the reconditioning kits anyway and next time the tank is off replace all the parts in the valve.

Best regards,

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post #2 of 11 (permalink) Old 04-07-2007, 04:38 PM
Grand Prix 500
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go get yourself a cup of tea after all that and chill! :wink:

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post #3 of 11 (permalink) Old 04-07-2007, 08:29 PM
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Very nice writeup, Andrew, thanks!

One little thing though: don't forget to oil the air filter before putting it back together! The air filter should be saturated with Uni oil or some other oil for foam filters.

post #4 of 11 (permalink) Old 04-08-2007, 04:45 PM Thread Starter
Grand Prix 500
Main Motorcycle: Daytona 900
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Join Date: Apr 2007
Location: Cambridge UK
Posts: 134
Thanks for the reminder, should have mentioned that you need to re-oil the filter.

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post #5 of 11 (permalink) Old 04-12-2007, 02:32 AM
Formula Extreme
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good post- especially as its relating to something 99.9% of t3 owners will go through!!!

still have fond memories of replacing mine twice.

i had no joy with the repair kits. and why does it go when you have a full tank of petrol!!!??? chuckling to myself with the the thought of my juggling/sweating/struggling. second time around i did it with the petrol in the tank. lazy*****!

your not a red d900 are you?

see ya around mate!
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post #6 of 11 (permalink) Old 04-12-2007, 03:51 PM Thread Starter
Grand Prix 500
Main Motorcycle: Daytona 900
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Join Date: Apr 2007
Location: Cambridge UK
Posts: 134
Hi Derek,

Thanks for your feedback. Since the petrol leaked past all 3 of the carb floats as far as I could tell and when I inspected the float needle seals I could see no ware on them, there were not stuck or dirty and seemed to move cleanly, I assumed that the float valves were not capable of keeping the petrol back on a long term basis.

Are you saying that no fuel should leak past them even if the fuel valve has failed. As the bike now seems to run fine the idle is smooth (well as smooth as it ever has been) and it does not seem to be running rich looking at the plugs.

Clearly if it should be able to hold the petrol back then I am going to need to replace all three float needles or at the very least get the carbs apart again and clean them. The bike was not used for some time (by the previous owner) so it is possible that the rubber has petrol varnish deposited on it.

Can anyone recommend something for cleaning them, would carb cleaner be appropriate or is this too strong for the rubber parts.


Hi Johnny, yes mine is a red D900, have you seen me out and about?

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post #7 of 11 (permalink) Old 04-12-2007, 04:13 PM
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Andrew: Chemical carb cleaner will destroy rubber! Don't tell my girlfriend, but I have cleaned varnish off of 30-year-old rubber bits with hot water, dish soap, an old toothbrush & some elbow grease.

post #8 of 11 (permalink) Old 04-13-2007, 12:00 AM
Supersport 400
Join Date: Nov 2004
Posts: 91
Wow! Thanks for posting this! I was literally logging in to post a topic on replacing my petrol tap. Of course, around here, we call it a petcock, but I figured it out.

By the way, anyone know why it's called a petcock?
bajajoaquin is offline  
post #9 of 11 (permalink) Old 04-13-2007, 10:54 AM
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Bajajoaquin: I've always had an interest in etymology, so I looked up "petcock" to see if I could find any information on the origin of the word. I could not make this up!

"Cock" (the second half of the word, in case it gets censored) is no surprise: it means "valve" or "faucet," as in "stopcock."

No, it's the first half of the word that I found surprising. I guess petcocks must have been primarily used for controlling the flow of gases rather than liquids, as the "pet" in "petcock" appears to have its origin in the French word for "fart!"

Special thanks to for amusing me this morning.

post #10 of 11 (permalink) Old 04-13-2007, 10:44 PM
Supersport 400
Join Date: Nov 2004
Posts: 91
I'd known about the valve part. I was thinking it was related to seacock, a through-hull fitting. That made me think it was nautical in origin.

Maybe I'll track down an Oxford English Dictionary to see if they lay out that sort of info.

Thanks for looking it up.
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