(15-05-19, 10:21 PM)Trebus link Wrote: The igniter boxes on these are a bit fragile but are repairable. The transistors can be replaced by hand if you know what you’re doing. Normal failure mode is firing on 2.

As suggested, have a check through the wiring for any corrosion which will cause high resistance.

(16-05-19, 06:55 PM)His Dudeness link Wrote: I'd say unfazed is on the money. If it's a project bike that hasn't run in a while it makes sense that a ground might have been missed or the wrong connectors were plugged together. Another possibility could be that a component in the ignitor failed short so too much current flowed but that seems less likely.

[quote author=Trebus link=topic=25261.msg297809#msg297809 date=1557955318]The igniter boxes on these are a bit fragile but are repairable. The transistors can be replaced by hand if you know what you’re doing. Normal failure mode is firing on 2.

As suggested, have a check through the wiring for any corrosion which will cause high resistance.

(15-05-19, 08:49 PM)unfazed link Wrote: A few things can cause it poor earth allowing back feeding through the Ignitor, power connected to an earth on the ignitor or something plugged into the wrong place in the loom. Check the loom very carefully for damage and/or evidence of melted wires, ensure all the earths are good and check that everything is plugged into the correct place (wires going in match wires coming out) There are a few plugs which are the same size, but are totally different circuits.

(06-06-19, 07:43 PM)Dinger1962 link Wrote: Ok chaps got the xj to run quite well now my only gripe is when  i release the throttle it is slow to let off the gas .the carb snaps back nicely -throttle grip and cables all snap back as they should --bike ticks over as it should--bit stumped now --any ideas please --?

(25-05-19, 01:33 PM)Steve3351 link Wrote: ARF...finally sorted my carb issues... :rollin
First I had a bogging down while tipping along at low revs...open the throttle, and nothing ... for a few secs...then start to accelerate away.... turns out to be a clogged pilot jet...makes sense, since pilot jet is helping at low revs, not just idling, and wasn't working properly, but once main jet kicks in off we go.
Second problem...revs won't fall back to idle when throttle is shut off...NOT pilot jet, although some experts suggest that running too rich causes this problem. I went down that road and tried adjusting pilot screws...no difference except lumpy idling.
Put pilot screws back to factory setting.
NOT throttle cable, i fitted a new one and made sure it was snapping back all the way. NOT a partly open choke circuit.
Other expert points out that shutting the throttle should drop all needles into main jets and close them SMARTLY. If one needle is not falling for some reason (diaphragm damaged/not seated correctly or some tiny obstruction) then there will be a delay in revs falling.
I took off the carbs, and without dismantling them completely opened the tops and made sure the diaphragms were seated correctly and the sliders were working smoothly....BINGO..! Blip the throttle and she revs up and falls back like a good FZS should...took it for a burn and experienced bliss of perfect throttle response....this video was a big help - http://www.youtube.com/watch?v=IBFq9nHVmks&t=62s
thanks for the comments and advice