at 85000 miles, I noticed there was more vibes from the engine. I was puzzled as the fuel consumption & performance were the same.

Tried two different tankful of fuel with no change.

I thought it was my imagination but as a last resort, I had the plug changed (CR7). The one that came out looked very good so I looked like a waste of time but...

The engine has become smooth again (more like sewing machine than a tractor) and I am a happy boy.

How often do you guys change your spark plug. I also read some found CR8 (colder plug) make the engine run better. Any ideas as to why??

How often do you guys change your spark plug. I also read some found CR8 (colder plug) make the engine run better. Any ideas as to why??[/QUOTE]

I had a similar improvement when I changed to an iridium spark plug after about 4000 miles.

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XTz 660 tenere, adventure spec bash plate, main stand, skid marks tall screen, Oxford tail pack 36 litre. Kobra hand guards, Bigger cast footpegs, Zen overland luggage plate, USB power point, iridium spark plug, TKC80 f k60 R tyres, o2 and fuel Kev mods, DNA stage 2 filter. bark buster bar wieghts, Touratec side stand base and GPS mount. Led spot lights

I got the best improvement from a CR8EIX Iridium plug. The standard plug, CR7 and its Iridium equivalent (CR7EIX) both made the bike feel lumpy, and I originally thought it was a problem with fake NGK plugs.

I think it may have to do with the power commander / stage 3 making the engine hotter? So a higher rated plug is required for me?

Not sure of the exact combustion science, but it works for me.

It'll only cost you a few quid to try it out.

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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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