Found two options (see below) for a higher compression piston in the stock bore but didn't find a lot of info in the forums on this let alone test results.

I contacted 3pracing about the Wiseco piston and according to them it's a straight fit in stock cylinder and the piston was custom made for them which makes sense as there is no other info on this piston on the web anywhere. It says 11:1 'standard' compression ratio but as it looks to have a raised dome seems incorrect so not 10:1, I sent them an email to question this.

What do you guys think of this one? If the piston is exact 100.00 mm I would probably need to hone the cylinder. I'm planning to combine it with a head porting job. If people are interested I could post before and after dyno results.. when I find a dyno willing to operate in the weekends or evening that is . I'm running a 2005 XTX with stock ECU - should I be worried about knock with RON 95 or 98?

http://www.3pracing.com/en/wiseco-pi...0r-xt660x.html



I also found a CP one that was posted here before, but I didn't get a response from the shop so far:

http://www.gw-racing-parts.de/index2...is=2010&lan=en

So I went ahead and ordered the Wiseco piston and received it last weekend after some logistical issues. After some doing some measurements things seem to be in order. It seems to be a Raptor 700 piston (which the label also states) but in 100 mm - I don't think any other shop sells them so I guess it actually is a custom.

Some specs:

• Piston weight = 405.6 grams -> Does anyone have the weight of the original piston?
• Dome height = 3 mm -> Anyone know the standard clearance volume so I can recalculate the compression ration?
• Specified clearance = 0.076 mm -> I do not have a micrometer available but caliper showed 99.95-99.97 at thickest part of skirt.

So I'm hoping it will be a straight drop in, fingers crossed. Will post some updates when installing in case anyone else is interested.

Attached Images

	SAM_0997.jpg (70.6 KB, 31 views)
	SAM_0996.jpg (54.6 KB, 27 views)
	SAM_0998.jpg (85.5 KB, 26 views)

Let us know how this goes for you pal I'm interested

I made some calculation on the compression ratio and the 11:1 seems accurate if piston to deck height remains unchanged (I'm not sure yet about this).

Assuming 10:1 is the exact stock compression ratio this gives a combustion chamber volume of 73,3 CC. The dome has a volume of approximately 7,8 CC.

659,73 cc + 65,5 cc / 65,5 cc = 11,07:1 CR

I have been working on the engine the last week, so far things look good. The piston + pin is about 20 grams heavier than the stock one. Piston skirt is only slighly shorter.

While the head was off I have also adjusted the ports so they are a bit better flowing, no adjustments to valves.

Once the bike is made whole again it's off to the dyno somewhere in the next weeks for a tune.. will post some results here as well.

Today I had the bike on the dyno to have a custom PC map made and to see results. As you can see in the graph I ended up with 53 bhp and 70 Nm at the backwheel which I'm pretty happy with! The first run of 49.8 bhp is one of the maps I got from the forum (CaptMoto's map) - the bike was not running to great on this too rich at low rpm as you can see. I was running a soft rain tyre on the dyno, the guys from the dyno place remarked that a hard street tyre would most likely have added a few bhp.

Bike runs great now the new map also made a big difference! Plenty of power, big increase versus slip-ons and fuel mod only I have used 95 octane with the 11:1 piston without any signs of knock / detonation - even when the bike was running lean, I do plan to run 98 octane when I can though. I will see if the map can be added on the forum as there is no map yet for a similar setup.

The bike had the following setup:
Wiseco 100 mm 11:1 piston
Stage 1 headport
K&N Stage 1 & snorkel removed bigger snorkel hole and 4x 1 inch vents in side
Superpole slip-ons
PCV
15T front 47T back

Attached Images

xt 660 dyno2.jpg (176.6 KB, 45 views)

Nice work mate, would have been interesting to have done a dyno run before doing the piston to see the difference on paper but I know thats not always easy. I have done the stage 2 hot cam mod and just tuning my power commander with my seat of the pans o meter
If you want it to sit a revs more happily I suggest the stage 2 hot cam, moves the power up the rev rage a bit and the motor just feels happier at higher rpm.

Thanks. I'm happy with the low end torque for the X. Plan to do a R or Z build in the future and where I would like to try bigger displacement with the 50/50 or stage 2 cam

Cool stuff! Did you notice any increase in vibration due to heavier piston or higher compression?

I never noticed any extra vibrations with my big bores on this motor.

__________________
Click here to join the XT Supporter's scheme

Mods that I have done to my XTX's

My 04 XTX
Stage 1 & 2 DNA filters / Kev fuel mod / snorkel mod / Drilled air box mod / Engine breather mod / Fork Spacer mod / 15w fork oil /
[
My 07 XTX
Raptor 700 cylinder 102mm / Modified Crank Case to take a 105mm Raptor Cylinder / 11:1 102mm JE Raptor piston / Stage 1 Raptor Hot Cam / Ported head / Colder Spark Plug / +2mm Throttle body / DNA stage 1 & 2 filters / Modified Air Box / Snorkel removed / Worry Brothers stage 2 filter cover / 6mm & 8mm Bolts Replaced with Titanium Bolts / Recovered seat in Black / O2 Eliminator /

My 09 XTX
59HP at the rear wheel / Stage 2 Raptor Hot Cam / DNA stage 3 Air Box / Carbon Can Exhausts / Modified Exhaust Link Pipes / PCIII With Custom Fuel Map / Wideband Commander O2 Data logger / LCD100 Dyno Jet display & fuel adjuster / 2500 OHM HT lead instead of a 10K OHM XT lead / Extra Coolant Cooler / Protaper Fat Bars / Tail Tidy With LED Tail Light / OKE Protection Knobs / LED indicators / AIS blocked / Modified rear sprocket rubbers / Rear Foot Pegs removed / 09 ECU With 02 Sensor Changed To A 06 ECU / Complete wiring harnes Changed from 09 to 04 / Home made LED resistor flasher / Hole drilled in the fuel tank filler neck to allow quicker filling / Modified Bar End Weights / Progressive front fork springs, 15W fork oil, forks lowered 25mm, used XTR rear links lowering the rear 20mm, rear spring one click stiffer / Changed front & rear guards from blue to black / 47T rear sprocket / Speedo Healer V4.0 / Kev throttle cam mod / Throttle grip mod / The new 2010 O2 sensor mod is out, works a treat, The new 2012 O2 Controller is out, PM me for details

Now ride a 2018 MT09SP ABS + TCS

My KTM 990 SMR Mod book. http://www.ktmsmt.com/viewtopic.php?f=13&t=4946