Petrol Leak !

[Locky]

Doing a few jobs on the Wee . Started it up for the first time in quite a while , left ticking over on the drive and noticed a leak , l/h side of engine , dripping onto the inside of the bash plate . Turned it off to discover that its petrol . Raised tank and restarted but no leaks . I'm puzzled !  

Any ideas ?

[willbo]

all pipes were connected fine? strange that

[Locky]

Yes checked all pipes , it was a bad leak while it lasted !

[greywolf]

The usual culprit is the short hose between the injectors shown in blue. It is almost always the cause of a leak that begins when turning the ignition on that stops later. The hose dries out and shrinks then plumps up when exposed to new fuel. Changing the clamps shown in red from OEM crimp clamps to fuel injection rated screw clamps, not typical worm drive clamps, often is enough but replacing the hose is sometimes required too. As long as you're in there, you might as well replace the hose. Cut the old one off as it is easier that way. In cold weather, warm the new hose to make it flexible enough to work it in. Continuous leakage may be caused by the hose or by a deteriorated O-ring between a fuel rail, front one shown in green, and injector. O-ring failure is significantly rarer though and doesn't go away by itself.



Use a fuel injection rated clamp. This is one type.


Do not use a worm drive clamp like this.

[Locky]

Thanks Greywolf , that was the first  hose I checked and it looked dry , I've left the tank raised and can see that pipe from the l/h side with a torch . The others with the O-rings also look dry . I'll start it again in the morning while watching the hoses and see what happens .
What the inside diameter of the hose between the injectors ?

[greywolf]

What the inside diameter of the hose between the injectors ?

I don't know offhand. If you are in there, you should be telling us.

Anyway, cut the clamps and hose off and take them to an auto parts store. Even if they aren't the problem, and they almost certainly are, I'd replace them if they were exposed. I'm going to do that when I'm in there putting in a cruise control connection when my new bike comes. Make sure you get fuel injection rated clamps. Some people used worm drive clamps and regretted it later.

[Locky]

OK I'll change the hose tomorrow just to be on the safe side , I already have a good selection of the hose clips that you mention , thanks again ...

[Gassoon]

Let us know how you get on Locksmith!  So do the worm-drives tighten up too unevenly over the surface of the pipe or something ?

[greywolf]

Let us know how you get on Locksmith!  So do the worm-drives tighten up too unevenly over the surface of the pipe or something ?

That's basically it. The size of the base of the worm gear and the step between the base and the band prevent good pressure all around. Worm drive clamps work okay on larger hoses and lower pressures but FI fuel lines run too high a pressure in too small of a diameter.

[Gassoon]

Cheers greywolf - this is the first non-carb bike I've owned, not used to all that fancy high-pressure stuff! Can see how that 'step' now seems significant! And I've just bought a giant box of hose clamps    Never mind, still handy in most situations!

[Juvecu]

If you're still looking for clamps I can recommend Mikalor clamps. They do constant pressure clamps in various sizes that are suitable for fuel hose applications. Here's a link to an eBay auction with various sizes. I've bought from that specific seller before as well and received good service and very quick dispatch and delivery. They also make excellent stainless steel exhaust clamps.

[Locky]

Started the bike up this morning and no leaks . So stripped the tank & airbox off to have a look . One of the crimp on hose clips could have been tighter , it could be rotated on the hose !
So I guess this is where the petrol came from (thankyou Greywolf   ) .
I've renewed the hose and hose clamps , which I already had in the garage .
Hose size is 6mm internal dia and 13mm external dia .
While I had the airbox off I treated all the electrical connections behind the radiator to some electrical grease and fitted my BMC air filter .

Thanks for the great advice ..

[Juvecu]

Bike sounds better with the new air filter then? You'll probably only notice it riding and accelerating though. My K&N definitely sounds better than stock

[greywolf]

I'm glad I could help. While not exactly a common problem, it is on the list of usual suspects that have been reported by a number of people. Contacts and connectors for headlight wiring, failed TP sensors and galled rear axle nuts are some others.

[Locky]

Yes there  is a difference in sound with the BMC filter . don't think I'll notice and difference in performance though .

[Manora]

Hose size is 6mm internal dia and 13mm external dia.

I know this is an old thread but, to update, I have had this problem and following the advice on pipe/clip size bought pipes and clips only to discover when I got to the actual job, that the 6mm pipe is too small. My K5 has metal pipe studs of 8mm and the hose is 7.6 or thereabouts.
Bike off the road until I get the correct pipe  
Time to get the CX500 out again