Z900 A4 fuel leak any ideas please?

[warren3200gt]

Hmmmm, cylinder 1 & 3 looks a little suspicious. 1 being lowish with no oil and 3 having a big increase with oil. Cylinders 1 & 4 are normally fairly equal as are cylinders 2 & 3. Cylinders 2 & 3 are normally a little lower than 1 & 4 as they are in the middle and get less cooling.
That said even cold cylinder one and 3 are within range and they would all increase by 10-15 psi when hot due to expansion of the rings. That's why you need ring end gap BTW.
Which cylinder did you struggle to fit?
Cylinder one increased by 25psi with oil. 2 by 35psi. 3 by 65psi and 4 by 25psi.
It looks like the tester wasn't screwed in and sealed equally.
I think I would be looking to retest. First spin it over to clear as much oil as poss from the cylinders then retest trying to ensure the guage is well sealed and compare result with those posted today.

[Gray17]

Thanks for reply Gray, manual says teaspoon of oil ( castrol GTX) which is what i used same on each, put finger over plug hole after oil inserted and turned over slowly to circulate it, before taking readings. As for cracked ring yes its possible but doesnt sound like it when running, will use the boroscope on that cylinder see if theres any scoring on bores with piston at BDC. As for shims checked each cylinder with cam lobe upward to ensure none sticking. Re checked clearences and all seem ok.
Warren, yes the low one is difficult to get a good seal as the tester has a brass ferrule with rubber o ring which you screw into plug hole it only has a small thread unlike spark plug, problem is that cylinder has a timesert so the o ring only rests on that rather then the alloy of the head like the 3 others, if that makes sense, so may be loosing a bit, the oil may well have plugged the gap, i could try that one with some ptf tape on thread. This doesnt happen with spark plug as its wider and longer thread and sealing washer covers more area.
Will re test as you suggest.

The real question here for me, is this yet another red herring (know its not ideal) or could this be causing the poor low speed running which is my main issue i need to deal with, would like to get a few runs out this season if poss after all money spent already. It doesnt oil smoke or seem to use any, and pulls strongly on main jet?
Thanks

[gray]

I would look elsewhere and optimise everything else before lifting cylinders and barrels, committing to time off the road with summer coming on and incurring £££ for new gaskets etc. But that's my personal tuppenceworth

[Gray17]

Hi Gray, thanks for reply, yes thats what im hoping for too.
Thought with all the knowledge and expertise on the forum someone could give me a definitive answer but maybe too many variables?. I know its a case of eliminating issues 1 at a time but where to start. As you say dont particularly want to pull engine apart yet again full rebore etc then still have same issues, this is what i meant by red herrings. I know the results aren't great, perhaps with hindsight should have had it rebored at the time, but bore looked good, ring gaps good, no wear lip at top and pistons looked good too, only stripped it for vapour blasting not for an issue as such. All are within manuals tollerances of 100psi though.it is possible i cracked a ring, but without re stripping no way to be sure? Im still of the opinion its carb related, perhaps bigger pilot jets may help, but dont have a box of bits to try and can get expensive and may not even be that.
Yesterday fitted new Zpower points plate complete with new condensors and wiring, set points gap, today going to time up with strobe and re check compression in no.3, plugs have been cleaned ready to re fit, will also re torque head again, bikes not mine Ha!
Then see where we are at then.
Update today
First off checked torque on all head bolts everything still ok
Next backed off air screws an extra 1/2 turn as people seem to think not enough fuel getting in to pilot side, i may need to increase these to next size up?
Then as Warren suggested re checked cylinder 3 compression again, used a different o ring on tester thread and got a better seal came up to 120 psi which is better then when i 1st tested it, however if i put a teaspoon of oil in in still comes up to 170 psi which is a 50 psi difference def not ideal. Thats cold on full throttle, fully charged battery.
The other 3 are all around the 140- 150 psi so new o ring made a big difference. Of course ive no idea how accurate the tester is but as all are tested using the same the diff will be equal on all.
Spun engine over several times to clear oil in bores then refitted spark plugs. As i understand it squirting oil in bores and getting better readings is more down to piston ring/bore wear then valves not sealing properly?
Re fitted tank and started it up, loads of smoke but to be expected as ive squirted pure oil down the bores.
Still doesnt run right though, i found its when it backfires it ejects the rubber inlet caps, as did so whilst i was watching it, obv the timing needs re setting on the new plate assembly. Before i do that may take plugs out again and check theyre colour but expect blackish.
What i now know for sure
New Denso plugs fitted
Carbs all temoved re cleaned and blown through with compressed air.
New Standard size Genuine Keyster carb kits fitted all parts used.
Rob upgraded choke plungers to viton seals
No leaks on carbs, all have fuel in them and dont leak anymore.
New points plate complete with points, wiring, condensors pattern but from Zpower so decent quality.
Ignition cam stripped cleaned and lubricated along with bob weights, advance works ok, but will re check its only at 2500 revs or above. To ensure weight springs ok.
All 4 seem to fire ok, dont black smoke or use any oil, they all get equally hot when running.
What the hell can it be???
Thanks

[r3sc]

Thinking about what you said in your last post. If it’s backfiring through the carbs and popping the rubber cap off, to me that would suggest seriously advanced ignition timing on that pair of cylinders which is igniting the charge before the inlet valve is closed.

Or, the inlet valve on that cylinder/cylinders isn’t closing properly at times and when the fuel/air mix is ignited by the spark, the increased pressure of the ignited mixture is firing back through the inlet tract.

I would re check once again the relationship between the piston position, the spark and the inlet valve position.

Keep at it, you’ll get there eventually.

[Gray17]

Thanks for reply, yes think your right as only started popping cap off after id set timing with strobe, silly thing is it was really retarded before. The aim is to get the 2 marks 2 line up with the strobe flickering ie on 1 and 4 you want the F mark to align with the case mark (assume it doesnt matter if trigger is on lead 1 or 4 as the both fire together?), then do same on 2 and 3, to do that on the old points i had to move the plate fully and the pounts plate fully to get them to allign at which point the cap blew off during the run, at 1st thought it ran better but actually ran worst on the 50 mile run., also getting about 100 miles to going on reseve is this about right at 60 mph ish est 30mpg?
Tried to do this on new zpower points plate however whichever way i turned plates to full extremety the 1 and 4 F mark would not line up, nor on 2 and 3 either, somethings def not right, to make matters worst carb 2 now overflowing, it wasnt before, or at all since fitting new carb kits.
Back to going round in circles again, getting very frustrated and dissillusioned now, if i wasnt in it for so much id sell it on.
No idea what to do now as no sooner fix 1 thing another crops up!
Are they all like this or is just mine and been unlucky?
Cheers guys

[moizeau]

Old bikes/cars are fun. I balanced the carbs on my ST after playing with the frame, ran great on the remote tank. Put it back together, fine. Started it 3 days later, fine but left it on prime by mistake. It weed itself. Went for a run, really fluffy low down, few blats and closes on the throttle, spot on after 5 miles. I've not even looked at the insides of this engine, no idea where the valve clearances are or the compression. It has electronic ignition as opposed to points. Still running the plugs that it came with, cleaned though.
Did you ultrasound the carbs or just cleaner? Had a nightmare with the Zeph11 Cv's. Still have one that plays up, will need another US.
Stick with it, it'll bring the biggest smile ever when it goes as planned, then you can sit back with several beers and laugh.
Oh, and are you running a fuel filter, it is on me todo list, sure that why it weed itself and ran fluffy after removing the tank and swilling some shite around

[r3sc]

Humour me and forget the strobe at the moment and rig yourself with a 12v bulb on a couple of lengths of wire and set the timing manually one set at a time using the timing marks and turning the engine over with a spanner.

Set the points to the correct gap and then connect your bulb to earth and the points. Turn the crank in the correct direction very slowly until the lamp goes out and see where the timing marks are. You can the set about adjusting the timing by moving each set of points to suit the two pairs of cylinders. Moving the main base plate will move the timing relationship for both sets of points simultaneously but moving each set will adjust each pair individually. A larger or smaller points gap will also affect ignition timing but if you try to gap the points to the nominal figure and use the other adjustments, that’s the way forward.

Do the timing by adjusting each pair a small amount at a time and re turn the crankshaft to check that you’ve adjusted it the right way. As soon as the lamp goes out at the exact time that the timing marks align you’ve cracked it.

Once you’ve got one set correctly move on to the other set. Be methodical and don’t rush.

Once you’ve done the timing statically like this it should run ok and you can use your timing light if required to double check the advance etc.

[warren3200gt]

r3sc, one proviso, Graham has the replacements that have a adjuster for each points set aswell as adjusting thing the back plate. Many repop plates don't have the adjusters on each set of points.

[r3sc]

Hi Warren,

I’d assumed that he had the individual adjustments for each set of points as it shows in the parts diagram.

If this is not the case then as you know, the procedure may be slightly different.

Cheers.

[warren3200gt]

Yeah, the ones without are pointless (excuse the pun )

[r3sc]

I’ve just looked on the Z power site and if it’s the pattern one they have shown that he’s bought, each set of points does have its sub mounting plate.

He’ll get there!

[warren3200gt]

Fingers crossed.

[Grog]

Hello mate - quite the week you're having!

Lots of good advice already re. timing settings. Like the rest, I'd be leaning towards it still being a timing issue; you were definitely going in the right direction until you retimed it, when things started to go backwards again.

I agree with r3sc - forget the strobe for now and get the static timing right - you can end up driving yourself mad if the basics aren't in place to start with. One other tip that I find as useful as the bulb-on-a-wire method. If you're turning the engine over by the bolt on the crank end you should have all the plugs out anyway to make it easier to turn. Lay plugs three and four where you can see/hear them. When the points open for the relevant pair you're timing up you should hear a crack (assuming your hearing's OK - I have to make sure I'm listening with my left side or all is silence ) and see a spark as the plug fires.

Don't give up - we're all invested in this now!

TTFN Grog

[Al]

Next backed off air screws an extra 1/2 turn as people seem to think not enough fuel getting in to pilot side, i may need to increase these to next size up?

IF they are air screws are you turning them the right way to richen the mixture?

Does the strobe have an 'inductive pickup' with a direction arrow on it? If it does then it makes a difference which of the two plugs on any given coil you test on!

AL