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I've changed all the Plugs on my bike and checked the coils ect which seem to be fine now, this sorted the missfire problem for me for all of 5 min ! I've now gone about checking oil levels ect when I noticed liquid dripping quite fast from the left side of where the carbs are while the engine was running. I thought this might be water, but it is deffinately petrol, come to think of it I could smell fuel quite strongly before I changed the plugs out.

Any one had this problem before? I'm new to this DIY so any details would be great.

Cheers

Steve

The fuel leak is quite possibly cause by faulty float valve o-rings. Had a similar issue on my race bike, changed these and hey presto...no fuel leak. Fuel pump continues to deliver fuel to try and re-fill the float bowls as its leaking past these seals, some fuel may be running from the overflow on the carb too as a result of the constant delivery

Hope this might be of some help.

Scottie

I've cleaned all the carbs out checked the floats ect cleaned out with carb cleaner and blasted with an air duster. the only thing I haven't done is the fuel/air mix screws (not sure about re-setting these to the correct setting).all the seals were fine on the carbs too. Put them back on the bike and the problem seems to have gotten worse - please help, should i clean the air/fuel mix screws out too?

Did you completely dismantle the the carbs? I.e remove the float valves (the ones with the wee tea strainer filter on the top)? The seals I'm talking about are fitted to this part.
To be honest it would be uneconimoical to change every seal for new so If they continue to be a complete giraffe then i'd just buy a different set of carbs from ebay or from someone on here.

Job done, no more fuel leak , but now it sounds like a tractor and not half as much power, would this suggest that its not fireing on all cylenders now? worth noting ive changed all plugs and checked the coils ect. got it booked in at the garage for a compression test next wednesday, this is going to be expensive me thinks !!

Thank you for your help.

Hi there,

I've been having problems with my bike and it sounds like you had the exact same problem as me. My bike started to leak and sounded like it was only firing on 3 cyclinders. We got the carbs all cleaned out and parts replaced which cured the leak but it was still bogging down below 4000rpm. We also had the valves/compression etc checked but still no cure. My bike is still running rich which seems to be causing the problem but its funny that the carbs have been checked over and over again. I was wondering if you managed to find a cure for your problem as this could help me. Cheers!

I never cease to be impressed by people who can diagnose that a bike is running rich....................yet dont seem to have been to a dyno and actually had it checked.

as for running on 3, 2 or one cylinders.....................it easy to check and identify which if any cylinder is not running.................an exhaust downpipe will be very very hot test it like your old granny used to test an iron.................go ask her how

I've had my bike in two motorcycle dealerships and my Dad is a car mechanic and everyone says it is running rich, although there are no leaks, the bike stinks of fuel when it is running sometimes and the end can is covered in wet, black soot. I've spent a load of money getting the engine checked over and the carbs cleaned out properly and parts have been replaced and checked which means everything should be running fine, but it isn't. I'm not being paranoid about the bike running rich, below 4000rpm the bike is absolutely gutless and unpredictable until it starts to pick up speed.

As for checking that all cylinders are firing, Granny came over and it seems that they are all ok at the minute. How serious do the burns on her arm need to be to show that the bike is running at the correct temperature?

Thanks for your comments, they were very helpful.

nothing you've said convinces me that your bike is running rich

unleaded fuel always leaves a black sooty end can in my experience

Running gutless below 4K is no surprise and not conclusive evidence of running rich...................they all do that as they say

IF it is running rich it's one of two problems...................too much fuel or not enough air.................hardly difficult to figure out.

you need to see the skin lifting off grannys finger when she touches the downpipes

Hi All

I hope someone can help, I deresticted my 1992 ZXR 400 today by taking out the plates in the carb and now i seem to have petrol leaking out of what looks like a over flow from the bottom and dripping onto the starter motor.
The bike seems to run ok just ever now and then it would revto about 2500 rpm and then back to normal on its own.

Cheers Dave

If its revving on it own to 2.5k i would say thats an air leak, so you might want to make sure you have bolted down the inlets rubbers up tight and the clamps. Could well be the o ring that sits between the rubbers and block needs replacing.

As for your leak, do what others have done above and give the carbs a clean out, could be a bit of dirt in there dislodged when you took the restrictors out. Im now wondering though if you mean from the bottom of the float bowls? theres a small spigot, if its that, then nip up the little allen bolt, thats a drain outlet.

Hello Thanks for getting back to me i will have another look at the air box, The petrol seems to be dripping out realy from the side of the carb, There is a main petrol pipe going to the carb and on ethier side of this there is a small clear pipe, The petrol seems to be coming out from the one on the left of the petrol pipe as you sit on the bike.

Hello, Please could some one help. I had fuel leaking from the carb overflow back in Sept last year and have had the carbs cleaned and balance that same month and it stopped.

Now i seem to have a very simaler problem, The bike is leaking fuel again from the carbs and is fluiding herself out( not running on all four), I have taken the tank off and run the bike with out the tank and any fuel at all. (the bike still runs for about 15 minutes). When it runs out of the fuel it has left in the carbs i put the tank back on and start her up. (no more leaks) and bike runs good.

When i start the bike again in say 2-3 days time i have a leak again..
Is it some thing to do with the fuel tap maybe?

Thanks Dave

Have u tried draining the fuel out of the carbs via the drain screws? Does anything other than fuel come out?

Nothing to do with the fuel tap, your float valves are not shutting off the fuel to the float bowls when they are full. This will be because either the floats are damaged, the heights are set wrong (it would be odd for the height settings to just go out of their own accord without being messed with) or there is dirt stopping them from working properly. You will need to take the float bowls off the find out which of these it is.

Have you had the bike stood over winter and if so did you drain the carbs before laying the bike up? If the answers are yes and no then there is a good chance the carbs are gummed up. Petrol breaks down into varnish and sludge quickly nowadays and should never be left in carbs for months.

Is you fuel filter clean or is it letting crap through? What is the condition of the inside of the tank, is there crap in there and corrosion?

It sounds very much to me as though you have got crap in the system and need to remove and flush the tank, replace it or seal it if it is corroded. Don't leave petrol stored in the fuel system over winter. Just cleaning the carbs again without finding the source of the problem will not be a long term fix.

BTW, this is not an Engine & Transmission issue and it is posted in the wrong section (the OP is to blame here too). It's obviously a fuel system issue. You'd also do yourself a lot of favours by starting a new thread in the right section rather than digging up a year old one to tag a new post onto.