[Heffo]

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You might remember that I had a problem with flooding a couple of months back and Jason was able to help with that. I'd hit a block of wood that fell off a truck and the bike hopped into the air and after that petrol was leaking out of the carbs. A mechanic pulled the plastics and tapped the float bowl and that fixed it.

Well my choke cable broke 2 weeks back and I got the mechanic in again. He pulled the plastics, air filter box and while disconnecting the choke he noticed some perished rubber tubes that needed replacing. So he had to take carbs off to get at them. Replaced some tubes and decided to strip and clean the carbs while they were out. So far so good. Put the carbs back and started the engine and now the petrol is flooding out into the exhausts and onto the floor almost as quick as I can pour it into the tank!
Took the carbs out again (we already checked all the fuel lines first and they were fine and connected right, as we had marked them before dissassembly) andopened the float bowls and found nothing amiss. The mechanic blew out everything again with an air line and put them back into the bike and started the engine, leaving the air filter lid off so we could see into the top of the carbs. After a few seconds we could see the right carb spitting fuel from the small brass holes at the top rear and left. The petrol is just dumping into the engine and straight into the exhaust.
At this point the mechanic is really baffled. All hoses are connected properly and he is about to give up unless someone can shed light on this please. :crying:

 

[Goldwinger1984]

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It sounds to me like the mechanic overlooked some hard to see dirt or foreign object, but, if not, and the needle and seatare truly clean you just may have to replace them. I have seen needle valve sets become distorted and leak due to overtightening.

Vic

 

[Jason]

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If the fuel is pouring out as fast as you say then a stuck needle sounds unlikely. Has to be something the mechanic put back wrong. Did he reconnect the overflow pipes correctly? They are the two metal pipes that attach to the short rubber ones each side at the top of the carbs and the excess fuel that isn't being used gets pumped back to the tank through them. Check to see if they are kinked or blocked.

 

[Heffo]

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Okay Vic & Jason, thanks for replying. I seen the needles and jets being cleaned etc and I don't think the guy overtightened any jets. I've just been out to the shed and disconnected the overflow rubber pipe from the metal one on the affected carb and ran the engine. No fuel is coming out of the rubber hose, so this is the problem right? The one on the other carb is working, the fuel comes out at a fast rate but none from the affected carb. I took off the rubber hose and looked for blockage but it is clear, so I'm stumped again.

 

[wingnut]

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Dave,
If the bypass hose is not blocked and you are satisfied that the float, needle & jets were put back right (it's hard to put them back wrong in a 1500 carb as there are so few of them) then you must have a blockage in the chamber that vents the excess fuel. Even if the float needle was missing or fited wrong the fuel wouldn't exactly leak out in a flood on the floor like you suggest. There is a small (about 8mm) metal blanking plug covering the chamber (just follow the bulge from the hose to the carburrettor front, you can see it with the carbs installed) and see if the plug is still in place. There's never any reason to remove this plug, but if it is missing then get an air line in and blow into it to clear any crap away. This may be your problem, worth a try anyway.

 

[Heffo]

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Okay Steve, I've been peering into the guts of the bike for the last 15 minutes with a torch and I located the spot where the blank plug should be ( I traced the bulge like you said) on the front upper right of the body. There isn't a plug on mine but a rubbery sealant (black, maybe silicone) instead so obviously there isn't any dirt in the passageway as the sealant is keeping it out. The mechanic is coming over in the morning and I'm off work anyway so we will look further then.

 

[Jason]

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Actually Steve may be onto something there. There shouldn't be sealant there, only a metal plug. If the sealant is too far down the passageway it will be blocking it and won't allow the exces fuel to escape back into the tank. How did this sealant get there? Was is there before you pulled the carbs first time?

Why not just pull the sealant out and see what happens when you start the engine? You can always put more back in after (not too deep though if that isn't the problem.

 

[Goldwinger1984]

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I thought the fuel is dripping into the intake and coming out the exhaust? If that is the case then it can only come from the needle and seat.If the fuel is dripping outside the carburator then it's got to be a hose or fitting before the needle and seat. Please correct me if I am wrong here. Is it possible that the fuel enrichener valve is stuck in the wide open position or not seating correctly?



Vic

 

[Skooter]

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Vic, That passageway on the carburrettor is a vent for the return pipe. If it gets blocked the petrol will take the easiest way out (remember that it will be a huge flow rate if the return is blocked, I think thats the key here) and will end up exiting through the small air holes in the top of the body and down the venturi straight into the engine, ending up in a pool under the exhausts. Thats assuming that what Dave says is correct, ie "petrol is flooding out into the exhausts and onto the floor almost as quick as I can pour it into the tank!"
A stuck needle or FE valve wouldn'tflood as fast as that,so without any offence intended to whoever stripped the carbs, I'd say he has made a mistake somewhere and the sealant where a plug should be is a good place to start as it's a visible error anyway. He has probably given the float, jets, needles etc a proper checking after the first time flood by now.

 

[Goldwinger1984]

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I have to agree with you, Skooter, if my understanding of the problem is correct.

It is very difficult to diagnose a problem like this from a distance especially if someone has done some unorthodox alteration to the stock system (sealer).

Get a good manual with clear pics and diagrams and be certain that everything is in the right place. Compare your bike to another that runs properly. It's got to work right if everything is in order, something is being overlooked.

Vic

 

[englishted]

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I think the point to be made is that even if the floats were flooded, petrol would still be coming from the bypass hose as well. The bypass hoses are always pumping petrol once the engine is running, they are like taps left on. If petrol ain't coming from one of them then the problem is in that area. Like Vic said it's hard to diagnose these things from afar, but the clue is the sealant. If it wasn't there before the carbs were worked on then that narrows it down to that.
Interesting to see what the Heffo guy finds out later on, I hope he doesn't keep us in suspense.:baffled:

 

[Heffo]

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The suspense is over Ted! It was the sealant. The mechanic came over and I showed him these messages printed out. He put the silicone in himeself. Apparently he initially thought the blank plug was covering the mixture screws so he pried it out and when he realized his error the plug was mangled so he just put silicone into the long deep hole. When he took the silicone out today it was a solid 30mm plug and at the end you could see where it had turned into a thinner passageway (presumably the vent for the fuel) so he made a new metal plug and just glued it in place. Started the bike with crossed fingers (& toes) and the flooding was gone.

Thanks for all the help lads, you all came up trumps. My mechanic said that he wouldn't have thought about the silicone being the cause and would have pulled the carbs again for cleaning.

 

[Goldwinger1984]

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Glad you got it going, but, I sure hope that mechanic wasn't charging you for his learning experience.

Vic

 

[Heffo]

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Goldwinger1984 wrote:

Glad you got it going, but, I sure hope that mechanic wasn't charging you for his learning experience.

Vic

Well it ended up that he only asked for half the money he had quoted me in the first place. I'm just glad it worked out with the info I got here, I had already begun to look for a used carb on the web as I thought my one was scrap.

 

[Goldwinger1984]

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Very glad that it all worked out well for you.

Ride safe, Vic

 

[Heffo]

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Update time; Did 150 miles yesterday (Dublin-Newry & back) andno problems whatsoever. The silicone in the carbs didn't do any lasting harm it seems. Thanks again lads.