None fazer Question (xj900f Igniter box)

[Dinger1962]

Hi  fellas n burds recently bought an xj900f to have a bit of a project to go at got it running last night then promptly burned out the igniter box (feckin melted) do any of you guys have any expierience of this before or any idea what may be the cause of this thanks in advance any ideas /info greatfully recieved cheers

[unfazed]

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.

[Trebus]

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.

[His Dudeness]

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.

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.

I don't think he's looking for corrosion. I think he's looking for signs of excessive current flow so burnt/melted connectors or wires. If the problem was caused by plugging the wrong connectors together or missing a ground the wiring could be damaged as well as the ignitor :'(

[Dinger1962]

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.

I don't think he's looking for corrosion. I think he's looking for signs of excessive current flow so burnt/melted connectors or wires. If the problem was caused by plugging the wrong connectors together or missing a ground the wiring could be damaged as well as the ignitor :'(
[/quote]


fitted another igniter box --immediately started to get hot again only firing on two cylinders 1 and 4 pleeeeeeeeez  help---

[His Dudeness]

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.

^^^ It's like unfazed said. Go through all the connectors, either the wrong connectors are connected together or there's a poor or missing earth.

[Dinger1962]

ok thanks wll do

[Dinger1962]

connectors look good cleaned each one individually strangely found a live wire attached where the coils bolt to the frame --unbolted it and bike wouldnt turn over-put back in place bike spun over still only firing on two--got day off tomorrow will try again losing hope fast thought the electrics on my lancia beta were bad -- :\

[Trebus]

They’re pretty simple electrics wise, just an old bike. But persevere and you’ll get there, loved my XJ900!

[Trebus]

Have you got a factory manual? I’ve just found a PDF which I can forward if you send me your email address.

[Dinger1962]

p.md you thanks.

[Trebus]

Sent the files to your email via WeTransfer

[Dinger1962]

Thanks Trebus will get into it tomorrow--

[Dinger1962]

Thanks Trebus most helpful turns out coil pack gave up in turn causing the igniter to overheat --ran on 4 to start with must have stopped working then i started hunting in all the wrong places thanks to all for your help --

[Trebus]

No problems. Glad you made some progress and hopefully get it sorted soon

[Dinger1962]

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 --?

[His Dudeness]

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 --?

The chap below had a similar problem a few weeks ago. Turned out the slides in his carbs were returning slowly so the idle was dropping slowly. If the slides return slowly it holds the jet needle up out of the emulsion tube so fuel can flow through the main jet when you don't want it too. I'd try taking the diaphragms out, clean the slides and the carb where the slides move, check the return springs. Then put it back together making sure the diaphragms are seated correctly.

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

[Dinger1962]

thanks wiil strip n clean sliders etc tomorrow --