Z1OwnersClub GB

My ’78 Z1000 has been bugging me for weeks now as she refuses to run right when I first start her.

I cold start the old girl with choke and no throttle, as always and she starts first time, every time. She runs fine on idle but as soon as open the throttle a bit she misfires – I can just about coax her down the road on a very small throttle opening, just above idle, any more and she goes lumpy and misfires. After about five minutes as she warms up, she runs better and after ten minutes and for the rest of the day, she runs just fine.

First I thought it was the Newtronic ignition not getting sufficient voltage but with a new battery, freshly charged, the problem is still there. I now wonder if it’s the fuelling? The fuel tap is a free-flowing Pingel, so that shouldn’t be a problem. Does anyone have any ideas what I could try next please?

Check voltage at coils, swap coils.... I am a little paranoid about coils at the moment, since I had a Dyna coil progressively fail!
RegardZ

Is the ol' girl on full choke when you start to open the throttle and the misfire happens? After checking the coils as Garn 1 suggests, when was the last time you renewed the air filter? When was the last time you removed and cleaned out the carbs?
I suffered once from water in the carb bowls, a really frustrating problem not easy to diagnose and caused all sorts of problems running rough on choke was one! once warm was ok but then start to run a little rough at 4000 rpm!