Fireblade issues

[petefoster]

At Curborough last Sunday I had the embarrassment of the cut off switch not working even when removed *eek* , the helicopter switch works fine but the cut off not at all

 

Anybody any ideas why, the earth lead runs from the battery to the switch then back to the starter motor, the switch works as it starts up the electric pump when engaged, I'm wondering whether the fireblade engine has another earthing route from the alternator which needs incorporating.

 

Also at tickover and up to 5500rpm it sounds like its being starved of fuel and sometimes cuts out, are the two issues related?

 

And finally, anyone know the correct procedure for bleeding a brake with two bleed nipples as I can't seem to get rid of the intermittent sponginess?

 

Any advice welcome *wink*

 

Cheers Pete

[Roger Ford]

That description sounds confused - the cut off switch should switch the positive, not the earth.

 

However, it should be possible to switch the earth so long as that's the ONLY lead from the battery negative terminal. When you say "back to the starter motor" do you mean to the earth point on the starter motor mounting bolt?

[charlie_pank]

Hmm, sounds like you have an electrical gremlin somewhere. I normally operate under the assumption that if it's affecting more than one thing, that shouldn't be related then it's an earthing problem.

 

What do you mean by the 'cut off switch'? Do you mean the one that used to be on the right handlebar of the bike? This isn't a 'cut-off' as such, it's an engine-stop switch - perhaps that's the source of the confusion.

 

When you say 'helicopter switch' I'm assuming you mean the one that is supposed to isolate everything from the battery. Normally both the + and the - terminals of the battery should run through this - your description sounds like it only isolates the starter motor - or perhaps you mean that it is earthed on the engine at the starter motor? Either way, your wiring sounds rather bespoke (it is a BEC after all!), without quite a lot more info it's going to be difficult to help!

[northernmonkey]

Have sent you a BM - Hope it's of use...

[petefoster]

thanks all,

sorted the cut off switch, earth lead from the alternator was short circuiting the switch being connected straight to the engine, now connected to the battery so the connection goes through the switch

 

still got the other problems so back to the drawing board ☹️ ☹️ ☹️

Cheers

Pete

[charlie_pank]

OK so your 2 issues now are engine hesitation below 5000 rpm and intermittent brake sponginess?

 

 

The hesitancy is going to be either spark or fuel/air problem. If it misbehaves at idle, what happens if you spray esistart in the intake? If that fixes it, you need to fettle your carbs - start with a balance maybe?

 

If the sponginess is intermittent then it sounds like you just need to change your fluid. Air bubbles in the system would be spongy all the time.