ZRX Misfiring problem update - Aaaaargh!!!

I've got a pain in the arse problem with the ZRX.

A month ago I put the Muzzy full system on. Pretty much straight away it started intermittently misfiring.

I took it to C and M at Ingleburn (they have a Dyno) to get the fueling checked and the jetting right. It was way lean down low and way rich up top (off the scale rich). On the Dyno it misfired like a bastard.

Craig got the jetting right and it's now spot on but the misfire is still there.

Changed the plugs, found a loose coil, thought yep thats the problem. Fixed it up, misfire is worse. Put the stock ignition advancer back on, no difference.

Checked the coils, the loose one was playing up, changed that coil, still misfiring..........could it be both coils have fucked up simultaneously?

It seems to get worse once it gets hot ie second run on the dyno.

So where to now? It's got us totally screwed. If anyone has a theory we'd love to give it a go. Alternatively if someone has any spare rex electrical bits lying around or a spare Rex that we could swap bits off until we find it that would be massively awesome but that's going to be unlikely.

So guru's I throw it open to you....heeeeeeeelp!!!!!!!!!!!!!!!!!!!!!!!!

Last edited by Glen on Fri Jan 20, 2012 7:32 am, edited 5 times in total.

Check the other coil pack Glen. Also, how exactly is it misfiring? Is it missing on one or is it a random misfire? Is it cracking and popping? If cracking and popping, it's most likely sparkus interruptus. Check all the connectors to and from the coils and to and from the CDI. Check the leads as well and the end caps. If it is missing on one all the time, then it could be a holed diaphragm in the roosters. If not missing all the time on one, then carry on.

Worth checking the battery too. The battery is like a capacitor so if one of the cells is on the verge of shitting itself it might be intermittently dropping out, removing the electrical circuit. Worth a look anyhoo.





Also, don't forget that all electrickery is operated by smoke. Check to make sure there is still smoke in the CDI. If there is no smoke left in it, then it's most likely that it's escaped and the CDI won't work anymore.

do you ride in the winter?...not that you guys really have one...LOL

just wondering if the battery was sitting untended for a while & coincidentally it started to fail when you put the pipe on

did you change anything else when you put the pipe on?

is it possible to get correct exhaust gas analysis for jetting with the bike misfiring?

btw in this situation i usually start with squirting a little water on the headers individually with the bike running & observe the evaporation rate...

a misfiring cylinder will have a cooler pipe

if only one is misfiring check the plug, plug cap & wire

if 1 & 4 or 2 & 3 are misfiring check the related ignition coil

if all four are misfiring check the pulse coil, igniter & battery

do you ride in the winter?...not that you guys really have one...LOL

just wondering if the battery was sitting untended for a while

Just thinking about it, could be the battery Glenno, with so little use prior to you owning it may be caput

It has no probs firing up etc but the batteries three years old. Would it cause a miss? Im almost willing to try anything. It's a weird misfire, you come out of a corner crack the throttle and it'll give a couple of little misses then it's fine, next three corners no probs then it'll do it again. On the dyno it can't get to redline.

Also when your just cruising it's fine. It's only when you get up it that it misses

Is the throttle on your ol cahn wankers hand? Could just be arthritis or RSI.

Poop in carbs, particularly pilot jets?

check the fault codes Gleno.

then re-tune the Power commander.


Happy to help mate

On the dyno it can't get to redline.

Thats a weird one

probably not relevant but the only pipe related problem i 've had...ever

an odd thing happened to my Hideous Barge once

it developed an 8 grand rev limiter...every gear

turned out the packing in my Hindle can had worn out

there was no misfire though...just stopped revving up

Ok so leads, plug caps have been checked, coils have been swapped over, fuels been eliminated, sidestand switch has been isolated and we still have a problem. Airbox checked still problemo. Next is to disconnect the KTric and see if that makes a diff, and the battery to see if that does anything. Craig is certain that it Electrickery that's the problem.

Failing all of this I'm picking it up next week and riding it as much as possible until it breaks, just not too far from home......

Alternatively I might troll around Ebay and buy bits out of the US and swap them over.

What a pain in the arse

You've got my number... I'm on leave till the 23rd.

You've got my number... I'm on leave till the 23rd.

As soon as I get the fault codes from the PC V I'll give you a call......

You've got my number... I'm on leave till the 23rd.

As soon as I get the fault codes from the PC V I'll give you a call......

no worries.
and when it breaks down, let me know and i'll bring my trailer and laptop and reflash it...

My ZRX had a similar problem.

Turned out to be the spark plug gaskets were leaking oil into the plug wells, then down the plug threads smothering the plug. Was on one cylinder tho.

Worth a check.