Starting on 3 cylinders

[nige]

Does anyone else have the problem of starting on 3 cylinders and it’s always number 1 cylinder that fails. I have run it a while, then swap 1 & 4 plugs and it fires okay. It’s had the carbs set up and balanced, new jets, new Dyna S coils and spark plugs. When used regular in warm weather it’s not a problem. Any feedback? Thanks.

[King of Kings]

Duff plugs? Try B7es equivalent in Denso

[Andy M]

Has it been on side stand for the period before starting ? If always number 1 cyl is it always same plug? If so all though plugs were good back in the day and a fouled plug could be re used not always the same now. Sometimes they never are the same again. How old is the fuel ? it can go off in 6 weeks and foul plugs . There are a lot of fake NGK plugs sold in the UK .

[floydsz1]

Pull the plug cap off the plug so it's almost touching the threaded top of the plug while it's running, it'll start to fire , let it warm up and then push it back on fully, my z1b does it and my zrx1200 aswell. You won't get a shock from it but if you're scared , use a pair of pliers.

[DavidZ1R]

Leaving on the side stand for long periods, the fuel drains into 1 from 2 , high level then floods the plug when starting, I usually drain carb1 when laying it up.

[kev edwards]

On the odd occasion it happens and it's down to when I park up without running the fuel ot of carbs with tap off, but years ago I had the same thing with another Z and it took a couple of years to solve, I put a stock exhaust on it and it never happened again.

[nige]

Thanks for the advice , just to add some more info , tried removing lead and it did arc out etc but nothing changed . the bike is always stored on paddock stand and i run it to empty carbs while stored .Checked carb manifold clamps are right and tight .tonight started it up again only on 3 no1 not going , ran for about 5 mins swapped plugs 1and 4 restarted all 4 cylinders running ,took it up the road and it goes as it should ,just don't understand it .Has anyone had anything similar? thanks

[zed1015]

Does it only do it when stood overnight and then ok the rest of the day once run.
If this is the case you should check no 1 before starting to see if it is wet with oil.
There's a good chance you have a leaking stem seal allowing oil to weep overnight and foul the plug and once 1 is swapped into a pre warmed cylinder and 4 into a now fuel washed cylinder the bike fires on all four.

[Mr Bump]

Worth trying a new set of plugs I reckon, also worth changing the relevant ht lead and cap.

If that doesn't help try swapping the coils over and see if the problem moves. Normally a coil would play silly b***ers when it's hot but you never know.

It could be an oily valve stem seal as zed1015 suggests but wouldn't there be a fair bit of smoke involved as it all warms up?

Olly

[warren3200gt]

No one mentioned choke plunger on that cylinder?
Once you've taken it up the road it'll have warmed up a bit and the plug swop you mentioned would have them firing on all 4

[nige]

Evening all, sorry its been a while getting back with a reply, thanks for all the advice.A old mate who is a restoration mechanic came to give me a hand with it .Last year it started running poorly so decided to take it to a reputable workshop who rejetted and set it up the carbs but still not spot on with this starting problem.Using a laser thermomoter we found 1 & 2 were both a lower temp and it was running very rough.Carbs off and bowls off,measured float height anywhere from 27/30 mm book says 22 +or-1mm reset to correct height also put new float needles in as no3 had kept flooding randomly then found small piece of rubber in needle hole.Reassembled with new airbag to carb rubbers as one of the old ones had a screwdriver shape hole in it.Balanced carbs using a carbtune ,just purchased and used for the first time,now runs on all 4 from cold and goes like it should. Sometimes you are better off doing it yourself with the help of the club and friends

[floydsz1]

Good news you've got it sorted, they're so easy to work on and dont require any special tools like modern bikes , all that's needed is experience, and that's where other owners come in. Oh and it's so rewarding once you've done it at home without a dealer.