I have done everything to my bike 2009 xt660r pipes dna stage 1 and 2 snorkel removed kevs mods 02 and fuel mod new chain sprockets new Cush drives and bearings oil and filter new plug and still surging 0-40 mph above that it's fine goes great my bike is in excellent condition done 7500 miles I'm gutted and getting sick of it it's a shame as I love my xt

Have you tried the twist grip (throttle) mod?

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No not tried it never seen it how do you do it please lie try anything m8

Twist-grip mod: http://www.xt660.com/showthread.php?p=154983

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Been there done that took Kevs mod off and fitted a PC mine doesn't surge.

How much did it cost for pc did you still have surging with keys mods on did the pc make a big difference

Only difference with mine I have the air box holes.

I took Kevs fuel mod off and bought a secondhand PC as much out of curiosity I found the surging you get is a like tooth when you have it can't stop poking and prodding!! I found the trick was to ride either on or off the throttle it didn't bother me all that much,but not something I think about at all now.

Re the PC just like everything else in life you only get what you pay for although I do run it with Akra's which having changed pipes not only on my XT but other bikes they are the best by the proverbial mile.

Hi guys been playing about over the weekend to try to sort out the surging I have all mods fitted so I ended up targeting the chain tension so took up a bit of the slack and it's made a big difference was just wondering do the xt like the chain to be quite tight

No, not really. Too loose and you'll notice slack/surge when taking up the throttle. Too tight is bad though. Can cause all sorts of woes and breakages.

One thing to consider is how old your chain is? Even adjusted correctly, an old knackered chain will cause sloppy take up of drive because of the small amount play at each roller/plate. A 110 tiny bits of play makes one hell of a big lot of slack when you take up drive!

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If you've come from a road bike you'll feel the chain more as it runs looser than your average road bike. usually if the chain is causing surging symptoms i find it's usually ready for a good clean and adjustment.

I have found some bikes of the same model can be more fussy about chain tension than others.

The throttle mod is certainly recommended.