Z900 A4 fuel leak any ideas please?

[warren3200gt]

The ones on the carb sides are airscrews,. So screwing them in richen the mixture and turning them out weakens the mixture.
If you still show rich at 3 turns out your pilot jets are too big. The jet size should be stamped on them. Both pilot and main.
Check sizes and report back.

[Gray17]

Morning Guys, well had another thought last night after searching rich running issues. The bike ran be it rough before fitting new voltage reg, the old one was allowing volts to soar to 15.7v and blowing fuses and bulbs, hence new combined one now fitted, which regulates it to 13.8v great, but then i remember reading lots have had issues with coils having low voltage. As voltage was high before, it means coils were getting good voltage, but now its where it should be, they could be getting less then their required volts.
Today its off with tank to check, if need be ill feed direct from battery to test, although know wiring is all good and switches are new (not that that means a lot with parts these days) if ok ill move on to removing the 4 carbs( hoped wouldnt have to do this as a pain to get in and out) and as Warren suggests re check all jet sizes and nozzle position. Another thing i read is if air screws over tightened in past can snap off the point so will check that too, i will also re clean and blow through all orifices and jets with airline. It may mean replacing all the parts with a Keyster kit, which for 4 are not cheap, but if i could guarantee it would sort the issue I'd do it in a flash, trouble is it may be something completely different. Think previous ones were pattern but gaskets only.
Another thing i read is how easy it is to get exhaust cam 1 tooth out, now im pretty sure i got mine correct, counted links several times and marked it, then turned engine over by hand and re checked but again its possible, but read another post stating bike would still run/start ok but be down on power, so perhaps another red herring? Although if wrong that will need addressing too.
Then theres the plugs they are genuine NGKs B7es, now manual says B8es are standard but thats Z1 not Z900 A4, but wouldnt explain black soot after a few mins of running, that def indicates too rich, yes wont run properly without choke on partly, which doesnt make sense as that makes it richer, when it should need to be leaner, also now ive adjusted air screws out to 1.5 turns bike wont run, it fires but wont start, its like its too weak, but plugs are black sooty? Argh! im back to going round in circles again. No smoke from exhausts which is good but you can see a haze which im guessing is due to the rich running, smelks it too? As new rings, guides , exhaust valves and stem seals fitted.
I'll try the coils first and go from there.
Cant believe im so close, but yet just out of reach of actually riding it.

[Ultim8pc]

I wrote this article based on my experiences of fettling Zeds and their carbs.
Most badly running Zeds are an accumulation of issues and rarely down to one thing.
https://airevalleyclassics.co.uk/badrunning.html
Hope this helps to resolve your issues.

[sean_rfi]

Hello Graham,
Just to throw one more variable into the mix but did you have the choke plunger seals replaced?
If these are still the originals they will have hardened or possibly cracked. In this condition the will allow fuel to bypass possibly causing the rich running you're seeing.
When I did my carbs I also polished the raised boss that the choke seals close off against as these with a little corroded/rough.

[warren3200gt]

When checking the jet sizes look to see how the size is stamped, if they look like second rate stamping, at an angle or generally just naff chances are they are after market dross.
Genuine mikuni jets have size and their logo stamped appropriately neatly.
If they are after market bin em for sure.
If your unsure if they are or not post a close up of the jet showing the size stamping and we can advise.

[Gray17]

Hi Guys, Firstly measured voltage at battery not running 12.6v, then removed tank and measured voltage at coils 10.8v so a drop of 1.8v which isn't ideal may well fit relay mod to sort this.
Next removed carbs not an easy job sure you all know this but had to be done.
Drained carbs float chambers 1 at a time they were all different but plenty fuel in them all. These need the gauge to get them all the same as at moment each has a different amount, also tabs quite bent on the 3 i havn't double washered them. However all 4 floats operate unhindered and dont seem to catch on anything, if you invert then back you can hear the float free moving. But obv they need to be all the same volume. So gauge needed to do properly.
Next checked main jets, the 2 outer carbs have 118 stamped on them, whilst the 2 inners have 115 stamped, is this correct, thought they should all be the same.
Next checked smaller jets next to mains all 4 are the same at 117.5.
Then removed the air screws all 4 are the same with a taper but not too a point they are flat on the ends is this correct? Nothing blocking the holes though.
I have yet to get to the chokes, i can vaguely remember when i stripped everything that they all looked ok but thats over a year ago.
Im going to give everything a good clean again and blow airline through everything again. There was no sediment in any chambers.
Another thing i noticed inner L/H carb and outer R/H carb have a brass tube (to the right of main jet) which has an opening so looks hollow, the other 2 carbs its a solid brass tube is this correct?
Finished up now back at it tomorrow.

[wilsonsjw11]

With the service that Rob Meggit offers with the choke plungers that should be the starting point once the carbs have been cleaned.
Regards
Steve

[warren3200gt]

115 in the center two and 117.5 (118 no such thing) in the outside is wrong. The middle two are the ones that run hotter so if anything you want bigger jets in them to be run richer. Do the main and pilot jets have the Mikuni logo on them? For sure someone's been in there and messed with them.

2022_04_04_13.13.00.jpg (32.42 KiB) Viewed 374 times

[Grog]

Hi Gray;

As per Warren's post (and Ultim8's earlier chart) for jet sizes - someone's been fiddling.
Flat ends on the air screws are correct.
Fuel level gauge is a good idea - £20 or so from ZPower.
Choke plunger refresh also a good idea, but unlikely to be the cause of your immediate problems unless they are properly mullered - which you would probably have noticed when you stripped them out!

TTFN Grog

[warren3200gt]

Mikuni jet logo. Appears on both genuine main and pilot jets.

download.jpeg (6.64 KiB) Viewed 364 times

[Gray17]

Agreed its def been played with at some point, i stripped each carb seperately and re assembled before moving on to next one so cant think im to blame, however been back to garage and checked jets again outer ones def marked 118 , inners 115, smaller jets are 17.5 not 117.5 my typo. See photos, i also note 1 of the carbs float post has been repaired, although this isnt the one that leaked and seems to work ok.
So whats best way to proceed, could try and get a replacement set of carbs online, but no guarantee they would be any better, obtain 4 full new jets and keyster gasket sets which would be over £100 + send chokes for repair to Rob another £50 not sure how long they would need to be away? Thing is if carbs themselves knackered im wasting money. One way or the other i need to get it running correctly,
1. Because i want to ride it after all the work and money thats gone into it,
2. If i decide to sell it needs to be right for the new owner.
However but i need to put the money where its most needed to actually get it running correctly, unfortunately ive no idea what that is.
Perhaps a bit of everything? At the moment ive got a load of things it could be but nothing definate ie how much difference would the jets make at low revs not much as needle jets work mid to upper rev band so its slow running jets thats got the issue nd their correct at 17.5 unless im misunderstanding, the chokes will cause poor fual consumption and rich mixture but not sure mine are that bad, least dont look it? if i knew it was def that, but think im guessing hence request for help if local.

[warren3200gt]

As Nigel said poor running is gererally down to several issues accumulated over the years. Those jets are suspect and I would replace them. As they not genuine I would suspect both the needles, needle valves and airscrews are not either.
Your right itheres no guarantee a replacement set would be a y better which is why I would always prefer to work with putting what you have tight. At least you then end up with a known quantity. Don't matter what the rest of the bike looks like unless the carbs are right it's all pointless. Money spent on the carbs is never wasted when spent on correcting po's butchering. Robs plunger service is money well spent and only a week away being done.
Have spent what you have on the rest of the bike the carb bits are peanuts and the best most productive money spent. Putting all the issues right in one hit is the only way forward or your end up twisting your melon man with fitting unfitting after every change.
Do it all, do it once, and the cost will be forgotten a minute after you press the starter.
List your set up, stock airbox, filter, 4 into 4 and stock setting will be all you need.

[Gray17]

Thanks Warren, sounds like good advice, just been on Nigels (Aire Valley) and facebook site the sets i need are out of stock, can get them on ebay but dearer. Rather use a forum member.
Was hoping to be out on it for Easter looks unlikely now so bit miffed!
Luckily weather down here naff all weekend!
Nigel, when are you expecting the Keyster Z900 A4 kits back in stock?
Thanks

[Ultim8pc]

Thanks Warren, sounds like good advice, just been on Nigels (Aire Valley) and facebook site the sets i need are out of stock, can get them on ebay but dearer. Rather use a forum member.
Was hoping to be out on it for Easter looks unlikely now so bit miffed!
Luckily weather down here naff all weekend!
Nigel, when are you expecting the Keyster Z900 A4 kits back in stock?
Thanks

I do actually have 4 kits that are set aside for a carb rebuild, but have new stock on the way. So I have put the 4 kits on the site so you will be able to order them.
Any problems, do let me know.

[Grog]

Gray;

One more random input from me after looking at your last couple of pics. The brass tubes you mentioned earlier - are they the ones at the bottom left of each float chamber in the bottom pic? If memory serves that feeds the fuel/air mix for start/idle. I'm pretty sure that all mine look like the top one in your second pic (that shows both float chambers together) , i.e. a small hole. Is it a catch of the light or has the bottom one been opened up considerably? Sorry to add to the can of worms!

TTFN Grog