Running rich on start-up

[grumpus]

Hi all ive a problem with my z1b, whenever I leave the bike for more than a few hours then start it up i get clouds of smoke out of all 4 pipes for about 30 secs before it clears.It smels like very rich fuel smoke not oil.I had the engine totally re-built a couple of years ago and have done about 1500 miles on it since. to try and correct this problem I have stripped and re-built the carbs with all the standard internals, had them ultrasonically cleaned. reset float heights with the special tool pipe thingy tested the floats by soaking them for 2 weeks in fuel ,the bike has a new loom, electronic ignition and Ive just put on dyna s coils (the green ones) as i thought the spark was weak, so new leads, caps and plugs, same result using ngk and nippon plugs.its running standard air box and filter and standard 4 into 4 exhausts, everything is set to factory standard. timing is spot on tested the voltage at the coils it was over 12 volts, im running out of ideas.
like i said it runs fine but only after the excess fuel is burnt off, once the smoke clears after 30 secs or so its ok.
I have the standard fuel tap with the the 2 outlets, and i have noticed when you take off the rubber caps from the balance take offs they are full of petrol?
help me please have i missed something???

[Taffus]

Hi Grumpus welcome back!
sounds like the float valves....

[grumpus]

Ive replaced them and set the float heights on the bench using one of those pipes you screw into the float drain hole so what else can I do ? the carbs dont seem to be overflowing???
p.s yes ive returned thanks for remembering me!

[Zedorset]

Just a thought, do you close the petcock when you park up, if so, is the petcock fully cutting off fuel supply when in off position?

[DavidZ1R]

I recently borrowed a gunsons colour tune to check out my z1r as the plugs always looked sooty, no not sweep before anyone comments, surprised at the difference after I used it, smoother at low speed, and plugs not as sooty.

[grumpus]

yes i always shut off the petcock when the bike is parked up, I have got a gunsuns colourtune this would show me how the engine is running but not what the problem is?
the plugs are very sooty as well

[ZedHead]

Definitely sounds like flooding. If you stop the engine and whip a plug out before the smoke dissappears is it wet?

[PAULJAC47]

Run the engine with tap off till it dies this lets you know tap is not passing fuel,next day turn on the fuel and start in normal way if it still smokes my money is on stem seals when engine done were oem or viton used?not the pattern ones in gasket kits? they usually go after a thousand miles or so..get some to follow you give it a handfull then roll off throttle quickly if you get a puff of smoke this will confirm seals passing...When you have set the float heights with the manometer method(clear pipe) i find it works best with carbs off the bike and mounted in a pair of carb rubbers then made dead level in a bench vice,recently did some carbs with pattern float valves,they all passed! replaced with some gen ones prob gone,also have known choke rubbers in the base of the choke lifters go hard and pass fuel..

[ollie]

Paul beat me to it ,i too am thinking stem seals ...hope this helps

[Coose]

My J does this if I leave the juice on when it's on the sidestand as it leans quite a way and as such causes the floats to drop. VM29 carbs dont have overflows, so petrol runs out of the filters and I get a nice dark rich petrol-smelling cloud for a few seconds on startup (you said in your first post that it wasn't oil).

My money is on a leaky fuel tap.

[Zedorset]

My J does this if I leave the juice on when it's on the sidestand as it leans quite a way and as such causes the floats to drop. VM29 carbs dont have overflows, so petrol runs out of the filters and I get a nice dark rich petrol-smelling cloud for a few seconds on startup (you said in your first post that it wasn't oil).

My money is on a leaky fuel tap.

I have had similar, just fitted new fuel tap. I see what you are saying about the side stand and carb floats could have some effect

[grumpus]

i will try the running with the fuel tap off and see what i get, the valve stem seals were viton ones bought from debben performance so not the cheap ones!
re- the choke rubbers,they are 41 years old so could be passing fuel with the choke on the revs go right up to 4k but i thought that was common with kawasaki chokes? ive got a gpz900r and it does the same!!! can you get replacements for the choke rubber componants? ? I ve not seen anywhere that supplies those? (if so where)
I think its defo a flooding issue, Im tempted to ship my carbs off to steve smedhurst or whatever his name is to get them setup correctly
when i rebuilt them AGAIN this spring i put new needle valves as well as new main jets in, i found out i had the needle clips in the wrong place Id set them up as z900a4 carbs (middle groove) but found some info about the differences between the carbs mine are late z1b carbs so needle clip should have been one grove higher so lowering the needles.
as i said i set the float heights with the carbs in a vice using the pipe tool.
i always leave the bike on the main stand when parked up.
ive always had issues with the airscrews not actually doing anything no matter how many turns in or out the were, but now the needles are in the right place they do seem to have some effect,the other issue i had was trying to get the tickover down low as i ran out of adjustement on the throttle stop screw the revs wre still too high? ive managed to tinker with the butterfly and have rectified that issue.

[PAULJAC47]

Choke seals are unobtainable as far as i know,always had to try and find some better ones,if you get hold of a Gunson colurtune you will see exactly how the engine is running,doubt sending the carbs to Mr Smethhurst will make any diff and will cost you!If you run the bike with the manometers attached you will see if the bowls are flooding,it can make a real difference to mixture how the levels are set i usually set to 2mm below the carb main body flange but you can go to 6mm if running rich.Some of the rebuild carb needle,jet sets are variable in quality to say the least.I recently compared some supposed a4 needles to some gen ones the difference was major in the width and taper,Tour max seem to be the best of the bunch gen obviously the best but well dear.As a starting point i set the air screws 1 1/2 turns out,set the slides to .7mm with a twist drill stuck in a piece of dowel,clip in the middle,set pilot mix with gunsons,then balance with gauges,starting on pot 1,then match 2 to 1 3 to 2, 4 to 3.What needles,pilots jets etc do you have in as a matter of interest?..Paul J

[Julian_Boolean]

My J does this if I leave the juice on when it's on the sidestand as it leans quite a way and as such causes the floats to drop. VM29 carbs dont have overflows, so petrol runs out of the filters and I get a nice dark rich petrol-smelling cloud for a few seconds on startup (you said in your first post that it wasn't oil).

My money is on a leaky fuel tap.

My J also does this, it has RS34s fitted and leaves a little puddle of petrol when I put it on the side stand, I store it nearly upright as it then starts better.

[grumpus]

all the jets /carb internals are standard. i will try the fuel tap test and also set the float heights lower I have a standard fuel tap fitted but it has gone very stiff with the ethanol, I did buy a replacement from z power last year but the quality was crap and it just leaked everywhere! at least i was able to get a refund from mr marsden as the whole batch they had were also rubbish, may change it to a pingel twin outlet type if it proves to be faulty, any issues with these?
may try and source some better float valves as I think i just bought a pattern carb kit back in the day.