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Ok, getting my Supporters organised....

Now, does anyone have a spare throttle body?
Or a cylinder head?

I don't want to use my standard parts, as I won't be able to put it back to standard when I, eventually, sell it.
Plus my bike is virtually new....so I really want to keep my standard bits.

If I can't find a Cylinder Head for reasonable money, fairly soon, I will just do the big bore conversion. (and throttle body, if I can get a spare).....There is a head on Ebay Germany, a breaker has one..280 Euro...too expensive.....but I have made an offer on it.....have to await the outcome

I haven't measured it yet but looked at the barrel, there is not much "meat" on it. I am going from 660cc to 700cc, plus 3mm. Its been done before, so it should be ok. The piston kit is on its way from the U.S.

I'm doing my first offroad escapade (it looks very gentle) this weekend with some guys from the forum. It is mainly gravel roads, in and around Stonehenge.....that will be enormous fun....first time offroad on my XT!

Bargain with them, I paid a lot less for the 2 I bought.

thanks Daz for those links....I think they are a little expensive, but useful. It should be easier to source than a cylinder head......

I haven't fully decided on the throttle body yet, and Kev can't convince me either... .....I really can't see me getting a gain worth talking about with a standard camshaft.
All the gains of a +2mm throttle body have been on much higher performance engines than on my project, and the gains are in the last third of the power band. The good thing is, it doesn't rob any low end torque/power though.

IF ONLY someone did a "fast road" cam...then I'd have one.

I just don't want a Stage 1 or 2...too extreme for me.

If you are after torque only, I think the standard cam is your best option. There are still a few more tricks to get more midrange power out of the XT motor.

One thing I have learn't from this XT motor is the more torque you have the more the motor feels like it is on steroids, very twitchy in the mid range when cruising.

I personally would not go with the 103mm piston. Assuming you get a stock raptor barrel, instead of re-coating it, rather stay with the stock 102mm and around 11 to 12:1 in compression. Boring the sleeve out just weakens it, especially if you want the thing to last in a road bike. Also it requires a lot of extra cash one could spend somewhere else on the bike to get a 103 mm barrel set up.

The flatter the top of the piston, the better, so try and avoid buying pistons with domes. If you look around, you might find raptor pistons with a correct desk high feature. The stock raptor piston has a lot of unnecessary deck clearance and the corrected piston sorts that out, without having to skim the barrel down. Again saving you cost, plus giving you a flatter piston.

The stock valves will choke up the 700cc motor. So I have found that +2 on the intake works well for me. Leave the exhaust stock. Note, when you port the head, don't increase the ports size itself. Concentrate on correcting the valve seat diameters and then blending the seats to the ports. PM me the sizes recommended by the guy who will be doing your porting and I will confirm if he is right or not. I don't like stating on a public forum what sizes I use.

Then, I run a +3 mm throttle body. I would love to go larger to around a 50mm, but that means you have to build your own throttle body, which is not that easy.

There are no gains from the exhaust by using larger than 37mm inside diameter headers. Reverse megaphone exhaust designs work great, if you can get them.

On raptor 700's I built and a big bore XT, breaking 55HP with these mods will be easy as pie. A 686cc raptor I built with a stage 3 cam and the mods above easily cracked 70HP, but the XT motor cannot pull the RPM you need to do that. 55HP should be easy to get, but I would say you need to aim for about 60 plus with the mods if you do this right.

Thank you Kev and Freez.

Freez, I have a cylinder wall of 4.5mm.
Rebore 103mm will leave me around 3mm. I HOPE that is enough left on there.......

hehe thanks Kev, but already ahead of you.....(a mystery shopper has already made offers on them!).....they are a little expensive....but much appreciated!!

has anyone tried a standard raptor cam....?
and are they all the same for 660 and 686?