erratic tickover

[grumpuszed1]

hi all my bike has an eratic tickover, it wont tickover at 1000rpm and when set at 1500 it will tickover but its very erratic, bike is zed 1b running standard carb and airbox with standard filter,4-4 pipes electronic ignition its always had a similar fault but since ive just done a top end rebuild i thought i would try and sort it once and for all, ive just done 300 miles since rebuild, so rechecked vavle clearances they are all between 004 and 006" i set them big so would bed in, the carbs were totally stripped inc the linkage everything cleaned,re-greased the carbs were also ultrasonically cleaned .ive just balanced them with vacuum gauges, they were lower than the stated 20-23 hg but i got them all to read the same also running standard coils leads and ngk plug caps and plugs which are all brand new
i followed the manual to set the carbs but it says adjust the air screws until the fastest tickover is achieved then lower it with the throttle stop screw but whatever i do the tickover doesnt rise??!!!
any ideas
cheers
graham

[london calling]

You might have an air leak somewhere
Check the inlet rubbers from the air box and the inlet manifold stubs.
A set of Denso plugs may also help,as many of us have found out NGK plugs can be fecking useless

[Steve S]

I would have gone for the pilot jets being blocked but if you had them ultrasonically cleaned they should be fine,might be worth checking again though and the pilot passages to make sure there is no blockages,did you set them up correctly once rebuilt? adjusting the air screws as the manual says should raise /lower the tickover to enable a smooth tickover once done.
Good luck.

[Dark Skies]

Could be a coil is breaking down or the body is cracked and leaking out. I had something very similar with a new CCI coil on my Z1000H. They replaced it on warranty and it fixed the problem.

[chrisu]

You might have an air leak somewhere
Check the inlet rubbers from the air box and the inlet manifold stubs.
A set of Denso plugs may also help,as many of us have found out NGK plugs can be fecking useless

agree. sounds like an air leak between the carbs and the manifold to me.

[Rich]

re-tighten the carb rubbers onto the head, as you have rebuilt the engine they will probably need reseating. Check coil voltages on tickover. Have you set the fuel heights?

[ollie]

rich ya beat me to it mate ,i would say the same

ollie

[grumpuszed1]

cheers for the feedback guys, firsty i used a smear of gasket seal between the head and the inlet rubbers as they probably are the originals, havnt checked the float heights worth a look as carb 1 seemed to overflow at times whats the easiest way to check them? also when i pulled off the rubber boots to do the carb balance they were full of fuel??? does this sound right??? the bike was cold and not been run for a week ??? i also pulled the plugs and they were black around the edge but the tip of the electrode was grey?

[paulmceleney]

apart from the bike not ticking over properly how does the bike run does it back fire when slowing down ?

[Taffus]

to quickly check if you have an air leak, run the bike and spray wd40 around the carb boots, if you hear the engine change rpm then you have leak. I used this method to check my 2 strokes (2 strokes are much more sensitive to air leaks)

[Al]

grumpuszed1
PostPosted: Wed Jul 23, 2008 8:27 pm Post subject:
cheers for the feedback guys, firsty i used a smear of gasket seal between the head and the inlet rubbers as they probably are the originals, havnt checked the float heights worth a look as carb 1 seemed to overflow at times whats the easiest way to check them? also when i pulled off the rubber boots to do the carb balance they were full of fuel??? does this sound right??? the bike was cold and not been run for a week ??? i also pulled the plugs and they were black around the edge but the tip of the electrode was grey?

I think it would be a brave man to read those plugs without seeing them, smelling the exhaust fumes and having regard for the ancillary set up but having had similar i could say that black round the edge is either too large a pilot jet (running rich) flooding bowls (running rich on tickover) too cold a grade of plug (rich dark markings after idle) fuel in inlets (too rich or flooding) If flooding you wont be able to get it to tick over either smoothly, or less than rich; however much you turn the screws.

Grey on tip is a different matter. Sounds like too weak but it may be retarded or too hot a running plug accompanied by flooding at idle.

There are many shades of grey but as a guide i always used to use the colour in the end of a disposable clipper or similar lighter. That would be light tan. Anywhere lighter than that and your getting in to dangerous territory. Having said that modern fuels do run differently to old leaded so as others have said on here before; better to errrrr on the dark side.

I believe the ideal mixture strength shows as an irridescence on the plug centre electrode and could you see it, a tide mark half way down the nose.

Hope this helps but flooding got to be the first thing to address.

If your balancing the carbs with vacuum gauges dont forget to check the choke circuits before you arrive at any conclusions about which if any carbs need adjustment.

One in a million shot; have you got tiny holes in the carb to head rubbers?? Not uncommon for people to use vacuum gauges with hypodermic needles straight into the manifolds!!!! Clutching at straws but i thought i would ask.

AL

[grumpuszed1]

firstly the bike does pop and spit back on overrun (a little)and when ridden it goes ok but does seem to feel a little choked, im not sure if this is because ive been using one of my other bikes (gpz900r) or because ive been running it in and dont take it above 5000rpm (indicated 80mph) when i start it on choke the bike starts after a couple of kicks but smokes heavily once started, its a very rich smelling smoke( not oil) and on full choke it will climb to 4000 rpm . i dont think there is an air leak cause ive tried the wd40 trick and nothing changed! i will try to post an image of the plugs on this post tomorrow

[DogsbolloxofZ1B]

Is your advance/retard unit OK? Make sur its not running fully advanced at what should be tickover. i.e. get hold of the cam, turn CW and see if it springs back FULLY. Just a thought.
Mike

[grumpuszed1]

binned all that malarkey when fitted electronic ignition!

[DogsbolloxofZ1B]

Out of interest what system you using then? I have electronic ignition and it still uses the advance/retard mechanism just swapped the cam for a one with a pole magnet in.