91' ZXR750 turned into a fuel fountain??

[Strika]

As Maddog said, if you had the tap on the on or reserve/prime position and the floats are stuck, fuel will continue to pour into the motor via gravity. The carbs on this model are CV carbs which work from vacuum, so they basically suck the fuel into the carbs. When the tap is placed into the Prime postition (if it has one) then the fuel flows freely. If it is a normal tap with On/Reserve and it has allowed fuel to flow while the motor is off, then you have something, most likely floats, stuck in the carbs.

A couple of hints the others have not mentioned. Keep solvents away from rubber surfaces. Use a dedicated carb cleaner which is less harmfull to rubber components. Refit the bits to the same carburettor, don;t swap parts. Use some rubber grease when refitting, one to lube and moisturise the rubbers and two to allow them to slide in easier. Just like sex...same principle, except the carbs will take you longer! If I think of any other handy hints I will let you know. BTW, usually a clean up will sort the Needle and floats, you should not need to buy new ones, it's rare that they flog out without doing loads and loads of klms.

[Gav]

Sitting on the edge of my chair....Can't wait for the next installment....

[Skinner]

@Maddog - The fuel tap was left open, I tested it today as recommended by ducati_paul, it works fine.
@Strika - I'm using carb cleaner around rubber parts and I think you're right about that gravity feed...my bike turned into Lake ZXR the other night.

Here's the update atm, I think we're making some progress, and possibly have the problem identified.

So after emptying my bike as per Tacks instructions above ^, I completely disassembled/reassembled the carbs.
I took care to not adjust anything I shouldn't.

WHAT I FOUND (I took pictures, can't figure out to get them off my phone, I'll try do it later though)
- the needle ends were black and gummy
- the jets were clogged
- the bowls were full of build up and crud.
- the little metal plugs - (fuel?) attached near the pivot of the floats on a metal tab - were jammed in their holes.

I rectified all of this (I thought) with some a can of carb cleaner, wire brushes, etc, and a fair part of my sanity over several hours.
Anyway, I reconnected everything, fitted new spark plugs and oils (tested the coils also, all OK) and tried to start.

One (and only one) cylinder flooded a bit, the other three fired for the most part. Currently the engine is again without plugs and carbs; emtpied and in the naughty corner of the garage.

My question now is: Is the float sticking problem something I can fix?

Thanks again guys for all the help.
Its the first time I've taken on something like this :S (I was into cars before)
and you've all been extremely helpful.

[Maddog]

@Maddog - The fuel tap was left open,
- the little metal plugs - (fuel?) attached near the pivot of the floats on a metal tab - were jammed in their holes.

Firstly well done...Working on carbies can be a little scary for the first time..I know the first time I pulled em down I was expecting bits and pieces here there and every where ,springs n shit going BOING when I removed this or that...

Any how..... not a good idea to leave the tap on when we got Dodgy carbs or fuel probs...
Lesson learnt there so lets put that behind us....

The little metal plugs you speak of are the needles the holes they were jammed in would be the seats...
So long as you haven't bent those little metal tabs on the floats the float levels should still be ok..

Sounds like the one carb thats still fueling up may have a sticking needle which will prevent the fuel supply from shutting off So now you only have 1 carb to sort and not 4...Take that needle back out of said dodgy carb and check the grey pointy bit on the end for any signs of wear then check the seat for any gunk...All it takes is a bit of shit to get in there (especially after a clean out) and stop the needle from seating properly and will let fuel in and flood........

[Skinner]

Working on carbies can be a little scary for the first time..

Agreed! Even my parents' 83' Volvo has EFI! Carbs are quite difficult, but it's something I've been interested in for a while.

I won't have time to work on the bike much for the next few days, but hope to have another before the week is through.

I'll post up my progress when I do.

[Skinner]

So close!

CARBS IN
The bike started!! Ran for about ten seconds before fuel started flowing out of the carb 4 (LH Side).

CARBS OFF
Cleaned out entire seat and needle assembly again, check all holes were free and drowned in carb cleaner before airing and replacing.

CARBS IN
Bike runs for all of four seconds before carb 1 (far RH side) starts pouring fuel.

CARBS OFF
I tried adjusting the float tang on the one that had been flooded with the aim of clogging it sooner, but it didn't help much.

What can I try now? The wax on/wax off is worrying me, one of the float bowls has a threaded hole already :S
I'm considering importing a set of carbs if I can't fix these ones, but really would prefer to fix this flooding issue seeing as I'm getting so close...

[Maddog]

MMMMMmmmmmmmmmmmm....So close...

May be time to consult your local mechanic and let him have a look...Or carby specialist..
Courageous effort on your behalf just to attempt such a daunting job....Well done
Keep us posted with any progress you may have yourself and or the outcome should you get it to the mechanics...

Sorry we couldn't quite get it sorted for you

Cheers Maddog

[seiko1]

Put a fuel injection kit on her

[Tack]

have alook at the floats and the pivots...make sure the floats can move freely to push on the needle to cut the fuel flow...make sure they are not sticking or touching anything to stop the movement. The tags on the floats must be able to push the needle easily. Failing that they might need to be adjusted...but would be unusual for the things to suddenly go out of adjustment though.....

Real long shot and not really likely is that the floats are taking on fuel...easy to check...when you take the floats out, give them a shake to see if they have anything in them...or submerge them and see if any bubbles appear...

[Skinner]

Put a fuel injection kit on her

haha I'd buy the injection kit if I knew a bit more about bikes, but as is I'm sticking with the old school

have alook at the floats and the pivots...

I've actually given up on these carburetors as of today - after continued float level setting (it's been a long day...) they refuse to stop flooding, looking at the fuel needle tips more closely though - one (the flooding one) appears to be warped/eroded slightly. I think this is my problem; it must not be sealing properly. All of the needles move freely on the float pivots.

So in the end, after trying to track down a full rebuild kit from the net, I've just ordered a set of refurbished carbs for ~$300 from a workshop in the USA. They're a mint set, not a bit of grime on them. They'll help with peace of mind after they're tuned. I'm quite excited, although they'll take 2 weeks to arrive

I intend for this bike to become a tidy fighter to join the stable here at home So will post a build thread sometime when it's made some real progress; I've been taking pics

Thanks again for all the help guys, I feel much more comfortable with my bike, it's good to have support when learning these things, as nothing feels better than doing something with your own two hands



- Skinner

[Maddog]

I've actually given up on these carburetors as of today - after continued float level setting (it's been a long day...) they refuse to stop flooding, looking at the fuel needle tips more closely though - one (the flooding one) appears to be warped/eroded slightly. I think this is my problem; it must not be sealing properly. All of the needles move freely on the float pivots.

So in the end, after trying to track down a full rebuild kit from the net, I've just ordered a set of refurbished carbs for ~$300 from a workshop in the USA. They're a mint set, not a bit of grime on them. They'll help with peace of mind after they're tuned. I'm quite excited, although they'll take 2 weeks to arrive

Sounds like a new set of needle and seats might have done the trick after all...
Good price on the refurbished carbs though...
Keep your old ones and replace the needle and seats when you can afford to and try em out..
If all good ya got a spare set of carbs or working ones to sell to someone here..

nothing feels better than doing something with your own two hands

And that something you do with your own two hands that feels so good....Is erm well your own business..LOL..

[Skinner]

Yes having a spare set is nice just in case I feel like rebuilding them one day.

And that something you do with your own two hands that feels so good....Is erm well your own business..LOL..

Hahaha I didn't even realise