91' ZXR750 turned into a fuel fountain??

Hi all I'm back with another problem

This time it's a bit more energetic! The bike is hooked up, all fluids and such are well.

BUT ...

There is fuel flowing at an amazing rate (i.e. it's bypassing the cylinders completely) from the carb fuel overflows. Both of them.

Now, before I take the carbs apart, is there something obvious I'm missing here? All lines are hooked up fine, the pump is running well and so on.

The bikes been sitting for a few months, but I put fresh fuel in...

Any thoughts would be much appreciated.

- Alex

Floats are stuck!
They'll have to come off

So I should disassemble/clean out the carbs?

Forgive my knowing these things

I'm keen to do it myself though.

Yes - you need to take the carbs off, take the float bowls off - and probably clean out a lot of crap, especially the needles & seats.......

One last thing before I set out on this mission - will they need to be 'synced' afterward?

I'm hoping no but assuming from what I've heard its a yes :S

Where abouts are you in queensland??

I'm at Norman Park, about 15 mins SE of Brisbane.

If you listen closely you can hear a trail of swears leading to me as I struggle to pull off these damn carbs

They're on their mighty tight, which I suppose is a good thing.

I managed to get one side to not spew fuel by just draining the float bowls, but the other overflow continues to gush premium all over my garage haha.

I'm persisting with my efforts to pull them off though, I know I need to get into those Float bowls.

Have you loosened the clamps round the rubbers the carbs fit into...??

Check the needles are'nt marked from wear or from sitting in the seats for so long.
(these will come out with the floats when removed)

Probally a good idea to replace needle and seats while you got em apart...
Be carefull not to bend the tab on the floats that the needle clips onto as this will change your float setting.

Really helpful advice, I'll keep it all in mind as I go along.

I'll hold off on the new jets for the moment (Getting parts for this bike has been an absolute pain so far) but if I get time I'll start making calls.

Just really want to hear it running at the moment

ARGH

I think I've just locked up my engine, at least for the time being.

I left the bike to have dinner, and reconnected everything as you do.

When I came back, EVERYTHING was flooded with fuel. Like the whole tank had emptied into the carbs for no reason at all. The key wasn't in the bike even.

I quickly siphoned out the fuel that was sitting on the butterflies and thought I should start the bike to burn any fuel left sitting in the cylinder. APPARENTLY THIS WAS A BAD IDEA.

A loud CLUNK later, it stuck. I hit the starter switch; the engine turned once and stuck.

I then realized that the ENTIRE ENGINE was filled with the contents of the fuel tank.
Please tell me I haven't destroyed a perfectly good engine This is the pits...

And if it's not broken somehow - how do I even get that fuel out?

Unlikely..it's possible just hydrauliced....

Take the sparkplugs out and spin the engine over...just as you would if you got water down the bores on an off road bike....but beware the fuel that comes out is fuel vapour...and arcing leads/plugs will set it on fire......or go booom.....so you need to pull the low voltage coil wires to prevent sparks...again...it's dangerous so be warned...

just be aware that the fuel washs down past the pistons and rings and down into the crank case.

Once you have stopped the fuel leak you need to dump the oil and replace...hard to get oil back up the bores though to reduce friction on start up...unless you put some oil down the spark plug holes and turn it over a few times....pretty smoky on start up if you do.

New needle and seats are quite expensive....$40 odd for the needle and $36 there aboutsfor the seat (by 4 of course).

The easiest way is to just buy a dynokit..kit and refurbish the lot (if you want)......or don't bother and buy yourself a new set of flatslides FCR39's but they will cost you about $2000

Last edited by Tack on Wed Nov 03, 2010 7:29 am, edited 3 times in total.

Maybe a diapraghm gone on the fuel tap? I had this once on a old GPz750, drained the contents of the tank, luckily I noticed my Oil Level was way too high and when I investigated realised the crank was full of oil/petrol mix! ... cleaned the bottom end nicely on the oil change though!

Ok so there's still hope. I''ll start the ringing shop marathon to try and track down get new needles and seats. It may be expensive but it sounds like what I need so it has to be done.

I'll check the fuel tap as well just incase that was the problem.

As for the engine come fuel tank, I'll do as Tack says.

1. Plugs out.
2. Disconnect coil packs.
3. Turn it over, watching out for the fuel.
4. Change oil.
5. Re-jet Carbs (and clean them out)
6. Reassemble, and put a few drops of oil down the spark plug holes.
7. Try to start it up again.

I'll definately take my time with this one. Might even end up taking the carbs into a shop to have someone look at them.

Thanks for all the help guys, I'll let you know how I'm going/not going

Also be careful when you turn it over. Don't bend over it to see how much comes out or you might get a face full of fuel/vapour. Might help if you put an old towel over it to help absorb what comes out but make sure anything you put over the engine with plugs out is clean as 'stuff' can fall into engine...

Maybe a diapraghm gone on the fuel tap? I had this once on a old GPz750, drained the contents of the tank, luckily I noticed my Oil Level was way too high and when I investigated realised the crank was full of oil/petrol mix! ... cleaned the bottom end nicely on the oil change though!

Did you leave the fuel tap on when you went to dinner...
We can pretty much say the needle/floats are jamming open hence the fuel flooding issue.

If the fuel tap was in the off position you have tap issues as well..as Paul has said in his previous.