Thinking of changing the spark plug on the XTX to them iridium ones and wondered if it's a gd way to go

Fank you

I’m currently using an Iridium plug, but I have to say it makes no discernible difference to starting, running, performance or economy over a standard plug (not that I expected it to). The only advantage of an iridium plug is the iridium alloy makes for a very hard centre electrode, it also has a very high melting point, which makes them last longer. Because they are harder wearing the centre electrode can be made smaller, which theoretically allows for a slightly lower voltage to create an arc and the arc tends to follow the same track more consistently. On the down side, iridium is very brittle (so the gap is pre-set and difficult to alter without risking damage) and a lot more expensive. They were originally designed to enable the massively long service intervals we have on modern cars.

Which you choose to use is personal choice, just don’t expect any improvement in performance. Most people who marvel at the new-found performance gains after fitting iridium plugs are just noticing the effects of a new plug, or rather how worn out their old plug was! Any clean and fresh, good quality, correctly gapped plug will do its job perfectly well on an XT660. Personally I always prefer to use NGK, over Champion, Bosch and Denso etc. Everyone has their favourites though!

However, what you do need to watch out for are fake NGK iridium plugs if buying on ebay. There are quite a lot in circulation and can cause running problems at best, and at worst insulator or centre/ground electrode breakage and broken bits of ceramic and metal in your combustion chamber – not good. Standard plugs aren’t often counterfeited because of their lower value, so you’re less likely to pick up a duff one. To spot a fake read this.

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Don't think I'll get them from eBay just to steer clear of that mine field lol

Dealers said he will knock abit of the price for me because it's Christmas lol so that can't be to bad

I tried an Iridium plug which was specified by my dealer as being the NGK CR7EIX.

I found it to be sluggish and choppy, and if it wasn't a single cylinder, I'd have said that one of my cylinders wasn't firing correctly... It felt like that.

I saw someone mention the same problem and he swapped it for the next plug in series, the CR8EIX which I did and it's a perfect plug for my bike.

Maybe because the engine burns hotter with the mods I've done, I'm not really sure but this did make a noticeable difference to performance.

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Bike: 2013 XT660Z, TKC70 tyres

Mods:
Barkbusters, Scottoiler, DIY Tail Mod, DNA Stage 3, Power Commander V & O2 Eliminator, Exan X-Black Stainless exhaust, Tool tube, Ohlins linear front fork springs, Nitron rear shock, JT front and Supersprox rear sprockets, D.I.D. VX 520 chain, Adventure Spec bashplate, DIY USB Outlet, DIY chain guide, Kev's Throttle mod

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Interesting one that. I did read the same OP regarding CR7/CR8 debate ( http://www.xt660.com/showthread.php?t=21527 ) and did go away and give it a bit of thought.

The 8 is a cooler plug, which isn�t quite what you�d expect to need when you�re moving from the leaner A/F ratios in the 14s:1 of a stock bike to ratios in the 13s:1 on a bike with modified (richer) fuelling. Sluggishness, choppiness and misfiring are usually attributed to a plug of too cold a heat range resulting in fouling. Generally speaking, richer mixtures will result in lower cylinder head temperatures, so you�d expect to change (if you needed to) the heat range of the plug in the hotter direction to prevent fouling and maintain the correct firing tip temperature.

What I did find out is that the 686cc Raptor�s stock plug recommendation is a CR8 (with a 0.6mm gap rather than the XTs 0.8mm gap as recommended by NGK). Quads are of course not subject to the same emissions regulations as on-road motorcycles, and probably don�t run as lean or need to be as clean, so maybe there is some logic in using a CR8 on a modified XT? Conceivably the CR7 may only be recommended for emissions reasons, to suit the stock lean burning catalyst equipped motor?

Not tried an 8 myself, never had cause to, but perhaps in the interests of science and experimentation, I ought to give one a go�

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