ZX10R 2004 misfires low RPM

Calumh96 · Two Stroke Sniffer Joined: 30 Oct 2018 Karma :

Im looking at checking out a fairly cheap ZX10R over the next few days.

The owner says he recently have a crank speed sensor fitted and it hasn't been set up with the power commander.
He says below 4k revs the bike misfires but past that runs as it should up to redline.
He says it wasn't like this before he fitted the sensor. Could be plugs coil or over fuelling.

Thoughts? what am i really looking at here?
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Current - K1 GSXR 600
Previous - K5 SV 650, ZR750, Lexmoto Adrenaline, HondaCBR125R, Lexmoto Arizona, Senke x6, Yamaha YZF125R, AJS DD125e, Hyosung Gv125, Jinlun JL125

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

...has he tried going back to before he fitted the sensor.

"It worked before I changed this sensor, must be the wheels."

Calumh96 · Two Stroke Sniffer Joined: 30 Oct 2018 Karma :

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

Maybe the new sensor is faulty. But yes, you'd need that to start the bike.

Me, I'd swerve that.

sickpup · Old Timer Joined: 21 Apr 2004 Karma :

A crank position sensor (CPS)on a modern bike is normally fixed i.e non-adjustable and I'm pretty certain you don't need to set them up with a Power Commander unless they now have variable timing maps for the spark.

The only reason to replace one is if the bike doesn't start and it definitely needs one as otherwise the bike won't spark so won't start.

If it is the CPS it it will show as a fault if you put it into dealer mode or will at least show as a previous fault.

Calumh96 · Two Stroke Sniffer Joined: 30 Oct 2018 Karma :

Update as i viewed the bike today

The bike runs perfectly as soon as you go above 4.5k RPM
Below 4.5k the bike pops and bangs and is quite boggy and underpowered

The owner says the bike was sat and then wouldn't start. The garage replaced the battery and crank speed sensor and the bike has been like this since.

The bike does have a quick shifter, aftermarket can and a power commander. The power commander has not been set up since the new can was fitted but ran fine with the can before this problem started

Yes the owner could take the bike back to the garage after lockdown but then the bike would be worth a lot more and currently I'm looking at getting the bike for at least 1k less than they value at.
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Current - K1 GSXR 600
Previous - K5 SV 650, ZR750, Lexmoto Adrenaline, HondaCBR125R, Lexmoto Arizona, Senke x6, Yamaha YZF125R, AJS DD125e, Hyosung Gv125, Jinlun JL125

sickpup · Old Timer Joined: 21 Apr 2004 Karma :

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

Agreed. There are PLENTY of litre sports that are working nice and won't need any work like that, could be £10, could be £2k.

I personally wouldn't risk it.