Engine flooding with petrol

[G0FHM]

And I mean literally flooding with petrol!

It's running out of the pilot air jets and filling the airbox too......

The carb needle valves appear to be all good..... when the float bowls are full, If I blow down the feed pipe, they are solidly closed.

The tank valve has had new O rings fitted, as they were both leaking. Now, with the lever in the RES position it doesn't run out, but I still get a drip every 2 seconds or so.

Any pointers as to where I need to start looking?

Thanks,

J

[Katgeezer]

Not 100% on this but I think you can build the tap back to front and that could make it act like it's on 'prime' all the time.
Also, are the vacuum and fuel pipes on the right bit each?

[bobster]

There are tiny O rings which seal the float needle valve seats to the carb bodies.........these shrink and dont seal, and let fuel bypass the needle valves.

Did you remove the needle valve seats from the carbs, you'll know straight away that the seal has shrunk when you remove them.

I just used some O seals I had in a box I bought. Or you could order some genuine Suzuki ones for 10 times the price of non standard ones!

[G0FHM]

Hi Chris,

The tap is working properly - On this one, the slot in the plastic valve that engages with the lever has 2 different widths, so you can only fit the lever the correct way round! Set it to Prime and it gushes out. Set it to Res, a small drip. Put a pipe on and suck, it gushes out!. The small drip may be of some concern though.

When I stripped the carbs down, no matter what I did, I couldn't get the needle valve seats out. I didn't want to force them in case I did some damage. That may well be the root of the problem.

O rings aren't a problem - We have a proper, old style motor factor in town and they carry everything in stock.

I'll pull the carbs apart.....

Thanks,

J

[bobster]

Stretch the diaphragm spring a tadd in the fuel tap..............measure it first and then stretch it so its 10 mm longer!

[fossie]

No matter if the tap is goosed the floats should stop the fuel going through, they clearly aren't working.
It only takes a tiny bit of crud to stick them open or even a score on the needle.

I personally would just get a replacement kit from NRP .( club discount ) for all 4 carbs and do the job once.

[spondonchris]

I agree with Fossie, it is nothing to do with the tap. Float needles should stop the flow and if they are not it must be they are not seating / sealing properly or the heights are wrong.

[G0FHM]

Well, the O rings are totally shot...... Over the years the edges have worn flat, and trying to remove one just resulted in it falling apart.

For whetever reason, when I first stripped the carbs down the needle valve seats would not come out and I wouldn't force them. After having decent Petrol in for a while, it's freed them off.

I've had a good look at the needle valves under the magnifier, and they appear to be all good.

I've sourced some replacement rings (for the extortionate price of 70p!).

Can't really test for a few days now, as the tank got lacquered last night and it's being left to go off. I haven't got an auxilliary tank (that people use for balancing etc) as they are too bloody expensive!

J

[callyboy]

Make sure those rings are petrol proof J. Need to be made from something called Viton or something. Anything else will just crap out.

You can make a aux tank out of anything really. I used a old scooter water tank. Could just use a bottle and some tubing.

You might wanna check your oil hasnt got petrol in it as well.

Cheers

Pete

[G0FHM]

Pete,

The O rings are petrol proof.... as soon as I showed matey the needle valve assembly, he put the yellow O ring box to one side, reached under the counter and pulled out the red box! I've used Viton seals before in electric motors that have a wet coupling.

I know the oil will have petrol in! The oil that is currently in it is not permanent anyway - I stuck a cheap 10w40 Diesel in, just for running it up etc and to clean some of the crud out. When it's ready to go on the road, I'll do a couple of fill/drops of decent stuff in quick succession to ensure the cheap stuff is out.

What kind of oil is a suggestion? I run Castrol ActEvo 4T in my Triumph (I'm not a fan of Castrol, but it's been run on that for years and Triumph specify it). Does the Kat tend to "like" one oil better than another?

J