Hi guys looking for some advice going to service my bike a 2009 xt660 r was woundering which is the best spark plug to go for the bike has a cr7 in at moment and has surging issues

Surging is more to do with fuelling than ignition. There's not a lot to be gained from changing to a different spark plug from that recommended by Yamaha. You could get an iridium plug (CR7EIX), but to be honest they won't make any difference to performance, they are simply designed to last longer.

The main thing is to make sure you have a decent quality, correctly gapped plug that is in good condition. Watch out for fake NGKs which proliferate ebay; these can detrimentally affect performance and have been known to shed insulators with serious consequences.

Spotting fake plugs - http://www.ngk-sparkplugs.jp/english/techinfo/fake/

BTW - I've moved this thread to the appropriate section for you.

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Cheers m8 I'm going to do DNA mods to filter to help with surging problems was just wondering which was the best plug to go for when I service my bike cheers I'm doing kN filter replacement and DNA mod 2 was wounering if I would have to remove snorkel as well

Stick with NGK CR7E would be my suggestion.

With these mods your likely to make the surging worse (weaker A/F ratio), unless you fit a fuelling device such as a Kev mod or Power Commander (and ideally an O2 controller for richening up the closed loop too). The main problem with the XT is it runs too weak in both the open and closed loop causing the surging. Have you, or are you intending to fit a fuelling device? Ideally you'd probably want to fit a fuelling device and O2 controller first up, then do the filters.

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Hi we're wil I get these mods from and what sort of money will it cost and could I fit myself I do really apreciate your help only had bike for a few weeks love the bike rides fab its just a bit lumpy under 40 mph don't think its been serviced for a while would this help

Both mods are available from Kev on this forum. You will need to send him a private message (PM) to discuss ordering. They aren't too expensive (very roughly �100 plus postage costs) and will make a real and noticeable difference to your XT.

They are supplied with full fitting instructions and are both simple to fit with minimal tools and skills.

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Cheers my friend thanks for your help

One other thing... If you join the XT Supporter's Scheme, you'll get preferential deals and access to the Ask Kev section (for 1:1 help and advice), as well as the ability to download the official Yamaha service manual for you bike amongst many other things. See the links in my signature for details.

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