[palace15]

I have just returned from a 21 day trip to the isle of Man and once a few weeks ago and about 4 times while away the C5 developed an intermittant misfire, rain or sunny conditions it did not matter, the bike always started and when it decided to misbehave it gave the impression of fuel starvation and would then misfire so loud that people were in fact coming out of thier houses to see what the noise was! if I was travelling around 40mph and the misfire started I could just 'roll off' the throttle and it would clear, the bike has a NGK plug, the only and nearest thing to me curing the problem was to let the machine idle for a while, the bike has now got 5200 miles on it, whilst in the Island I saw a couple of Dutch plated earlier Enfields but NO UCE models, the only UCE ones were in 'Paul Dedmans' shop in Ramsey

[JVS]

Maybe the spark plug cable casing/cover needs to be secured? Try checking the plug for any excessive carbon, that may indicate lean running, less fuel being supplied. < Opposite of this

Other members will have better insight into this. Hopefully (seems like it) it's just a minor prob and should be sorted out soon enough

[GlennF]

By misfire do you mean surging accompanied by the occasional backfire ?

[JVS]

Oh yep^

If it's the occasional loud bang after you roll off the throttle, then it's all good yo!
Happy New Year everyday lol

[palace15]

By misfire do you mean surging accompanied by the occasional backfire ?

Feels like the bike is holding back like fuel starvation then Bang!!

[Desi Bike]

Dirty injector or the plug is on its way out. More likely the plug is my guess

[Arizoni]

The backfiring sounds like it is running lean and the most probable cause of that with 5200 miles on the bike is a dirty fuel injector.

See if you can find some fuel injection cleaner at a automotive parts store.
They are usually fairly inexpensive and a little goes a long way.

As these are usually made for automobiles with large fuel tanks I suggest that you only dump in a few capfulls after filling your tank.  You don't want to over do it.

I've had excellent results with Chevron Techron but other brands will probably work as well.

[palace15]

Thanks a lot guys for the ideas so far, very much appreciated.

[GlennF]

Running lean means at low revs the engine will not fire properly, the unburnt fuel builds up in the exhaust system and then eventually ignites with a bang.

Until recently my bike had been running way rich and fouling plugs with black sooty carbon, which turned out to be a blocked air filter. A new air filter fixed that problem.

However now I have the problem you are talking about, with the bike running to lean, surging and backfiring. I am going to try injector cleaner as suggested above, and may also follow scooterbobs recommendation of setting the TPS to 0.7 volts rather than 0.6 volts.

[JVS]

Glen,

Am I confused here because in my previous post I said that lean running will soot up the spark plug? I must be wrong then. (Confused myself) I apologise for the wrong advice, palace15.

[GlennF]

Glen,

Am I confused here because in my previous post I said that lean running will soot up the spark plug? I must be wrong then. (Confused myself) I apologise for the wrong advice, palace15.

http://www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm

[JVS]

 ^ Yep I shall 

[Andy]

Until recently my bike had been running way rich and fouling plugs with black sooty carbon, which turned out to be a blocked air filter. A new air filter fixed that problem.

Awesome!  I've been having that issue.  Never even thought to look at the filter.  Duh!  Thanks.

[Arizoni]

Andy
If we are talking about the new UCE bikes, if you decide to blow the dirt out the filter, the air comes in thru the center and exits out of the outside diameter.

This is the reverse of most air filters so direct the high pressure air onto the outside of the filter body to blow the dust/dirt out of the inside.

[Kevin Mahoney]

put bike on center stand and wiggle the sidestand while running. If it cuts out fix. then check filter and buy a new spark plug.