Well, like you say, I quite often hit the rev limiter on my X.
I gotta admit, I do miss that surge of power high up in the revs like my old ZX10 used to have...

Hence why im tempted with the Hot Cams.

I never ride that hard Daz, so am the opposite to you. If I did any further mods, it would be without sacrificing significant low/mid range torque/hp. (Big bore sort of thing)

I like the Bottom/Mid range grunt my bike has, and I suppose 90% of my riding is below 5500 revs....just as well, as its an "R" !

Then a big bore kit is for you.

What I do know is a 12.5:1 102mm piston kit & a stage 2 hot cam will beat any XT660 with your mods across the rev range in HP & Torque from idle to top end.

hmmm....where to I get a piston kit from? Any links/recommended suppliers?

I was initially going to do a big-bore straight away, but didn't really get involved in it...then got (nicely) side-tracked along the DNA Stage 3 Airbox thingy.

I guess that a DNA 'Box and a big bore/higher comp. will be the mutts nuts for me!

I'm very tempted Kev!

http://www.off-the-road.de/XT-660/XT...Tuning/?lang=1&

should be able to help.

http://cgi.ebay.com/ebaymotors/YAMAH...Q5fAccessories

The best piston kits are CP at a price.
JE
Wisco
CP

A big bore on the XT offers more HP & Toruqe over the whole rev range, most of the XT,s HP & torque is hidden in the head.

Thank you Kev, I don't want to spoil your thread by going totally off-topic, but I see that link is for a 700cc Raptor, where does the sleeve/liner come from?

Who do you recommend for gas-flowing? Do you know anyone in the UK, Kev?

Not spoiling my thread at all, it's all XT related.

Two ways to do a big bore, buy a new Raptor 700 cylinder, or rebore & replate a XT660 cylinder. You would have to do the costing to see which is cheaper. I do not know of anyone one in the UK, as I did my conversion myself two & a half years ago.

You could always go with the mother of all big bores, machine your casings & fit one of these.

http://cgi.ebay.com/ebaymotors/NEW-Yamaha-Raptor-700-cylinder-jug-engine-BIG-BORE-_W0QQcmdZViewItemQQitemZ290458561243QQptZMotorsQ5f ATVQ5fPartsQ5fAccessories

How much cash do you have?

http://cgi.ebay.com/ebaymotors/Raptor-700-Cylinder-Head-Ported-1mm-Big-Valve-Cam-Seal-_W0QQcmdZViewItemQQitemZ350325415133QQptZMotorsQ5f ATVQ5fPartsQ5fAccessories

The only problem putting to much torque through the XT is it will more than likely break the gearbox.

hey Kev,
When will you send last dyno chart
I'm very curious difference with stg1 and stg2 cam
but your bike's
you know I bought stg 2 cam last year but not
install yet :)

I must admit I perfer the stage 2 cam to the stage 1.

With the stage 2 hot cam & the stage 3 air box it feels very simular to the big bore + stage 1 cam up top, I would guess my XTX is around 56/57 HP now. The bottom end is alot less without the big bore & higher compression piston.

I will get it on the dyno sometime.