Bike Z900 A4 not running correctly (FINALLY SORTED)

[Gray17]

Thanks for reply, never thought of trying that but can see the logic in your thinking. So question instead of the F mark im assuming at full advance your looking at lining up with T mark instead? Or which marks do you use?, also do you do both sets ie 1 and 4, then 2 and 3 or just the 1 set? Def worth giving it a go
Thanks

[zed1015]

Thanks for reply, never thought of trying that but can see the logic in your thinking. So question instead of the F mark im assuming at full advance your looking at lining up with T mark instead? Or which marks do you use?, also do you do both sets ie 1 and 4, then 2 and 3 or just the 1 set? Def worth giving it a go
Thanks

No! T is Top Dead Centre ..
The full advance mark is far right next to the bob weight pivot.
You need to time both pick ups seperately.
The 005 advancer has full marks for both 1-4 and 2-3 .
Regardless of that your tickover issue is very unlikely to be timing.

[Gray17]

Thanks for that Rob, i will check the advancer for the 2nd mark, i note statement each pair needs timing seperately but on the dyna S you can pivot the plate itself to adjust timing but both pickups are preset 180 deg apart and are fixed, not sure how you can time each independantly? As moving 1 also moves the other.
Or perhaps I'm misunderstanding.
If ignition is not the tickover issue are we then back to carburation again, problem for me ive replaced everything on the carbs other then the bodies and slides themselves, surely these can't be an issue?

[zed1015]

Thanks for that Rob, i will check the advancer for the 2nd mark, i note statement each pair needs timing seperately but on the dyna S you can pivot the plate itself to adjust timing but both pickups are preset 180 deg apart and are fixed, not sure how you can time each independantly? As moving 1 also moves the other.

The Dyna pick-ups are individually adjustable.
The two mounting holes on each one are slotted.

[kev edwards]

Am I to understand you have a dyna for a 650 on it, if so it's a different back plate so would make it more difficult for you to set up, if cam set up is correct and you have a good spark along with base carb settings which by all I've read on this saga last night the dyna looks to be the culprit, with the right backplate and on the right way round (backplate that is)they are easy to set up and as previously stated on full advance, all these things in place can only mean operator error is more likely than anything else.

[Gray17]

Hi Kev thanks for reply, yes the dyna was for a 650 but advertised as a 900 and yes back plate slightly smaller, however this has now been replaced with the correct size back plate with slotted adjustment. So set up not now an issue, or indeed its operation.
However taking others comments they say ignition unlikely cause of my poor running issues, can you elaborate why you feel this is the cause and any suggestions how to sort?
I am going to time it on full advance as suggested, but as long as thats ok and its sparking at correct time, with a good spark which it has what else is there?
The original points were replaced by a brand new Zpower plate and then the dyna on recomendations, neither have made any difference, which is disappointing , even the rebore has had little effect.
I'm of the opinion it could well be carburation, problem as everything on them barring the bodies/slides has been replaced new, the floats are set as good as i can get them, no longer overflow and each chamber fills, the only real adjustment are air screws tried numerous positions for these, everything set to standard, no air leaks far as im aware, needles new and set to mid position, starts on the button.
Ticks over erratic had to set to 1500 rather then 1000, but that could be tacho reading wrong? Its when you rev it, its seems to be holding back all the time rather then revving freely, also when you release throttle after revving it hangs before dropping back down, but sometimes then stalks rather then tick over, other times it ticks over but seems as though its missing, every so often.
Plugs are new Denso, caps are NGK but without metal shrouds.
I have looked under tank when running no stray sparks or shorts, all 4 cylinders have same output from silencers and got hot, all 4 front pipes get hot so def running on all 4. A good set of carbs would prove tbis of course, but getting hold of a set is proving elusive to say the least.
Im starting to loose the will to live at mo!
At this rate ill have replaced everything on the bike, well nearly!
Whats so demoralising is that everything ive done has made very little difference, it still runs like it did when i first got it, despite the numerous new parts and £1000s spent, not really sure where to go with it from here?

[wheelysteve]

Something you could try to see if it runs any better is to connect the vacuum take offs. Connect 1 to 4 and 2 to 3 with some 5mm fuel pipe or similar . This will mask differences between the carbs and may help running. Good luck with the bike and don't give up, you will crack it.

[kev edwards]

If you don't get this time, check that carbs don't have air correctors in them and you don't have both resistor plugs and caps on together. Start back at the begining, clearances, valve timing, ignition timing, carbs at stock settings, 12volts at coils, fresh fuel super unleaded, decent plugs not ebay ones. Check check and check again and again.

[Gray17]

Thanks for replies Guys,
Steve yes will give the rubber links in carb outlets a try, may help,

Kev no idea what restrictors are but when i stripped carbs down there didnt look like anything had been added.
Yes i know to check and re check, this stuff has been checked multiple times to the best of my ability, but that may not be good enough?
Valve Timing- 3 or 4 times as stated spot on
Clearences left slightly on loose side as know they close up after running, but this will prevent any valve remaining open if too tight, and inly downside bit noisier and loose a bit of power due to less lift, ill re do correctly after its bedded in.
Carbs - fully stripped cleaned, blown through with compressed air, all new gaskets jets etc, replaced choke plunger seals, set up to standard, float levels set up, air leaks checked. No leaks as far as im aware, standard air filter, but no damper tube, but that only quitens induction. No longer overflow, all chambers filled with fuel similar quatities in each when drained so valves doing their jobs.
Ignition- George mod done, good voltage at both coils,call 4 plugs teplaced with Denso and cleaned before using after rebore all gapoed corectly. Good spark on all 4 cylinders, all 4 pipes get hot at front and similar output at rear, no smoke.
Am trying to time it using strobe on full advance ie fast tick over 2000 revs, find it difficult to see marks as dyna s has much smaller opening then original, so a lot of the light from gun gets scattered. Will keep trying, but cant see that being the cause, but it does need doing so eill keep at it.

[kev edwards]

Open up the hole for your timing, air restrictors may be in the backs of carbs, these get installed when people put pod filters on, in a previous ownership this may or may not have been done.

Make up a damper tube as well, this may help stabilise airflow going to the carbs, unstable air flows can cause problems, had a thou once that didn't have its rear portion and it ran poorly until one was installed.

[Gray17]

Thanks, not really sure what im looking for will have to google air restrictors to see, pretty sure none fitted, but will re check.
As for damper tube, not possible to fit that on my bike, battery is bigger, battery casing been extended to suit and powder coated, and George mod fitted in space too. I had read on several posts that this was only fitted to quieten induction roar rather then any other reason, they are almost impossible to get hold of now anyway, plus dont believe Z1, Za or b had them, suppose could try and partly cover opening in airbox to simulate but it seems it needs more air rather then less as running rich?
Still struggling with the ignition timing at mo, no matter which way i turn cam plate the full advance mark wont line up at 2000 revs, tried a bit more throttle the same. This is what i was finding on Original and replacement points plates too. But yet everyone stated photo of the advance mechanism was correct for my A4 model. Def goes back when revs drop so advancer seems to be working. Moving plate revs do drop or increase as you move it, but the marks dont allign.
Feel im going round in circles again!
Just not getting anywhere at all, perhaps i have to accept its beyond my ability!

[zed1015]

PM sent..

[kev edwards]

Don't understand why you have a not needed larger battery, the weird george mod is an unnecessary mod that can mask existing problems, I mean air corrector jets, Zed 1015 will know more than most with these, I on a personal basis would get shot of the weird george mod along with battery and box and replace with a stock box, than fabricate the silencer box, you will then have a level playing field, it seems you are out of your depth and have too many unknown to you variables to effectively remedy the problems.

[Gray17]

Appreciate your reply Kev, but this is a problem that people have different ideas as to what could or could not cause the issues i have.
One of the suggestions was fit the George mod, this was backed up by several others stating low coil voltage is renowned for spark issues, so i fitted it. Now your saying it could cause issues? Same applies with Dyna S, one says get rid of points, no moving parts, nothing to wear out and fatter spark, buy that, then get told your better with the original points system? Suppose everone has their own opinions about mods and how to resolve things, i just want it to run right, finding the solution to that is the real problem!
Whilst i know the larger battery isnt standard it is def needed in my case and changing it will not make a difference to the poor running. It was already fitted when i bought it, as was modified batt cradle, ive merely had it powder coated. The induction muffler has been removed on many A4s now due to loss or damage over time and difficulty in getting replacements. So hopefully that wont be the reason mine runs badly, others have found theirs runs the same or better without it be it slightly noisier?
In fact i have pretty much gone along at great cost with most of the forums suggestions, unfortunately none have made a big difference to its ability to run correctly. Perhaps some of this is down to my own abilities or lack there of, in being able to carry out some of the suggestions perhaps with hindsight have bitten off more then i can chew, lesson learnt, will never buy another, prob too old now anyway.
But do need to get this at least rideable so its not a total loss, suppose i could strip it and sell the parts, prob worth more then as is? Or sell as ongoing project but would never recoup the money ive invested, or indeed enjoy riding it which is why i bought in the 1st place, to satisfy my curiosity since the 70s.
Thanks

[kev edwards]

Dyna s plate may be wrong way round.
Weird george mod not necessary, clean all connections and make snug.
Oversized battery not needed ever.
Are carb settings right for carbs?
Make sure airbox to carbs is free of leaks.