Z1OwnersClub GB

OK I have spent all last year and this so far trying to get my Z1000 to run properly.

Bike spec is:

Z1000A1, 1105 Weseco bore kit, gas flowed head, Harris pipe, New Dyna ignition ( but also tried boyer bransden and Newtronics makes no difference).

Engbine has a 20thou spacer under the barrels to bring the compresion down to 185psi. Ignition is set on standard timing marks.

So...I wanted to fit a nice set of 28mm carbs...I eventually got it to run, float heights at 26mm, 15 pilots (tried 17.5's as well), 107.5 main ( but have tried bigger).

Bike starts perfectly, idles and runs nicely on small throttle openings, but coughs and misfires on wider throttle and more revs. Tried various needles and emulsion tubes.

Carbs have 2 float vents and a vacuum outlet for fuel tap which is blocked off) The bike appears to be running mega rich, 4 sooty plugs and fuel in the inlets if you whip the carbs off before it evapourates. Air filter is clean and I have removed it to try and suss the problem.

If I block the float vent pipes it appears to improve.

The problems exist but are not so pronounced with the 26mm carbs...

Carbs were professionally cleaned, jets/needles are new etc etc...

Advance retard mechanism is also new...

Getting desperate coz I have run out of ideas

Beginnning to hate the bike...

tvm

Dale

Hi have you tried lowering the needles to see if matters improve? is the pipe new? if the baffle is removable see if its blocked or if bike will rev out with baffle out? had a Gs like this once only improved when i put standard pipes back on!!! Cheers Paul J..

Haven't tried that..better tax it and warn the neighbours then..

the main jets are to small it can be confusing when you look at the plugs just because its black doesnt allways mean its running rich do you no anyone that has a colourtune that you can use it sounds like your bikes running weak my bike that i spent a lot of time on over various weekends looking at the plugs was black until i use a colourtune and it turn out the bike was running weak it was a great suprise total opposite to what i though, hope this help you out

Do you have a good spark? A weak spark will not ignite the mix properly & cause the plugs to get sooty, there is a simple relay mod that can be found on here.

if you ain't got a colourtune get it on a dyno.

My A1 had an 1105 Moriwaki kit, Harris headers (but not can) and Z1R 28mm carbs in it's last incarnation - ran well on 115 mains. So your main jets do sound small for a start although there could be something else going on there too. Had that before where two or more problems cross over troubleshooting can be a nightmare. Double check you haven't a cam a tooth out.

Main jets defo too small ( Put 120/125's in as a starting point ) , Could be cam timing out a tooth but that usually just makes em run flat and as already suggested restricted exhaust ?. Also make sure new advancer is correct one and could be old coils playing up if not replaced with dyna's . If you don't get it sorted i could have a look if you get it to me (near goole) . Fresh eyes etc etc. Zed.

check your advance retard is not seized up.

zed1015 wrote:Main jets defo too small ( Put 120/125's in as a starting point ) , Could be cam timing out a tooth but that usually just makes em run flat and as already suggested restricted exhaust ?. Also make sure new advancer is correct one and could be old coils playing up if not replaced with dyna's . If you don't get it sorted i could have a look if you get it to me (near goole) . Fresh eyes etc etc. Zed.

Fresh eyes on the problem would be a massive help. Goole is close, I am in Brough/Elloughton just off the M62. however you'd be welcome to drop in for coffee and a chat anytime over the weekends.

I will check the cams. I had it on 115's in the 28's and will put them back in the 26's. If this helps then some 120 or 125's may be the solution. Then maybe I have a solution to the 28mm carbs

I will order up some 120/125's and will try them this weekend if they arrive in time. otherwise 115's will go back in to see. pilots are 15's as it wouldn't start with choke on 17.5's.

Ignition system is brand new Dyna kit inc coils and leads, I did have a new Boyer system on there with digital coils which was changed to the dyna. The Bransden ignition is on another Zed I rebuilt for a mate which has 1105, big valve gas flowed head, 33mm mikunis and a full race harris which runs just fine if a little lumpy at low revs probably due to the big carbs.

I haven't messed with needle positions as i think that is a fine tuning thing but is in the plan. What I need to do it improve it so I know I am going in the right direction. Bigger jets are not a direction I have tried yet...fingers crossed.

tvm

Dale

it is possible that your valve time is out but you said the bike was okay on tick over when you rev the engine is it slow to responed this what you would find if the valve time is out it would sound like its running on three cylinders

See what results you get after fitting the jets /checking exhaust restriction etc and if still no joy will arrange a look ok. What 28mm carbs are they ? If they have the pilot fuel mixture screw under the float bowl make sure it is only 1-1/4 turns out otherwise it will run massively rich, cough 'n' stutter and not want to rev out .

26's have the pilot air screw under teh floats, the 28's have airscrews on teh side of the carb body.

28mm carbs also had the idle screw pointing down under the floats but I rebuilt them onto the 26mm carb chassi to put it back on top. They also have a centre fuel feed rather than two pipes, one to each pair of carbs

Engine has a 20thou spacer under the barrels to bring the compresion down to 185psi.

NOOOOOO The only way to check the COMPRESSION RATIO is to measure the volume of the combustion chamber.... ccv....

Bike on side stand..... plug #4 out... set that cylinder to TDC (firing stroke) with all valves closed... use a syringe (about 50ml) with engine oil in it... Fill cylinder with oil & make note how much (about 30ml - ish).... to bottom of plug thread....

Divide the bikes engine capicity eg: 1170cc by 4 and the individual cylinder cc is 292.5cc, add the ccv (oil amount: 30ml?) and you then have the total swept volume, so if you have 30cc then the total would be 322.5cc, you then divide this total by the ccv, therefore 322.5 divided by 30 would be 10.75, this would be your compression ratio, 10.75:1 would be good.