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Bikes, Hints'n'Tips => Fazer 1000/FZ1 corner => Topic started by: Motopsycho87 on 20 March 2016, 03:14:01 pm

Title: High rpm misfire...
Post by: Motopsycho87 on 20 March 2016, 03:14:01 pm
Hi guys, been out for a 100 mile play today, towards the end of the ride me and a mate decided to drag race (on a privately owned airstrip...), after the first couple gears the bike started to fall flat. Now no matter what gear I'm in it seems to misfire over about 7-8krpm. It ran perfect in recent weeks doing the same, but all of a sudden today it struggles,it sounds more like it's on 3 cylinders than 2.

So besides the obvious, clean connectors, snip the HT leads, replace the plugs. Any other thoughts? Coils are pretty cheap so I'll snatch some up while I'm at it. Are there any common faults that would act like this?

Cheers!
Title: Re: High rpm misfire...
Post by: PieEater on 20 March 2016, 04:38:58 pm
Check the air intake to make sure nothing is obstructing it or has been sucked into the snorkel.
Title: Re: High rpm misfire...
Post by: Motopsycho87 on 20 March 2016, 05:11:09 pm
Ridden over a few leave but would be damn surprised! Added to the checklist though...
Title: Re: High rpm misfire...
Post by: Motopsycho87 on 20 March 2016, 05:32:24 pm
Apparently a white block of wires behind the left hand panel can be a problem?
Title: Re: High rpm misfire...
Post by: mick chiz on 21 March 2016, 11:13:23 am
check your exup valves working,(take cover off and move it with your hand)also a dry air filter can cause all sorts of problems if you have an aftermarket one,k+n or pippercross,make sure that they are oiled correctly.another thing it could be is the fuel filter,very easy and cheap to replace.ive learnt over the years to start replacing the servicing parts on a bike before going full technical if any running problems arrise
Title: Re: High rpm misfire...
Post by: Motopsycho87 on 21 March 2016, 04:44:05 pm
No EXUP on bike I'm afraid!
Title: Re: High rpm misfire...
Post by: Motopsycho87 on 26 March 2016, 01:49:36 pm
Right, so changed the sparks plugs, ignition coils and leads. Still no different. There was a lot of corrosion everywhere, but nothing obvious.


So now my next possible thought is the carbs. What can go all of a sudden and stop a cylinder running at high RPM? When I installed Ivan's I fitted new carb rubbers, everything was to spec, and it ran perfect. All of a sudden, one cylinder seems to be not firing, but only at high RPM, its perfectly smooth at low revs...


Cleaned out that 'white connector' with contact cleaner too, then slapped with white grease and re-assembled. Nothing.


Only thing that makes sense atm is a blocked main jet... in which must be a big lump of shit to achieve that!
Title: Re: High rpm misfire...
Post by: Motopsycho87 on 26 March 2016, 03:58:44 pm
A fucking dead ant in my main jet...
Title: Re: High rpm misfire...
Post by: PieEater on 26 March 2016, 05:03:51 pm
Mice in the airbox I've heard about before but that's a first !!!
Title: Re: High rpm misfire...
Post by: AyJay on 26 March 2016, 06:11:14 pm
Got to be a first!


Still, it's always good to find the problem so you can be confident of a fix.
Title: Re: High rpm misfire...
Post by: Motopsycho87 on 26 March 2016, 10:41:51 pm
The fix being poison pellets in the vent hoses...