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XT660 to XT734 Conversion
I am using Steve Ruth in Suffolk UK, to build the engine, and Cuervo Racing / High Desert Dyno in the USA for the parts and Cylinder Head porting.
My bike is a 2008 XTR, fitted with a DNA Stage 3 Airbox, a Power Commander, and Carbon Cans Exhaust. I have already sourced a spare engine to use. Specifications +1 mm Valves Uprated Springs Cuervo Racing Ported/Flowed Cylinder Head High Desert Dyno HDD5050 Camshaft Bored out to 734cc with a CP 105.5mm 11:1 Piston Bored out throttle body 2 or 3mm To fit this piston, Steve is going the route of : boring out the existing Cylinder, and fitting a liner. This seems an easier option than fitting a Raptor Cylinder, and doesn't need Nikasil Plating either. A more "lengthy" thread on this conversion is at http://www.xt660.com/showthread.php?t=14763 |
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Richard, your parts will be on their way shortly, this will be a great build but require some tuning at your end, we hope all goes well! |
thanks Dan...it will be fun!
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this I'll watch with interest
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Should fly.
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looking forward to the dyno prints :-)
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Since im making about the same convertion im going to write about my project too from 660 to 734
the final list of mods is: +1mm inlet valves stage 3 reprofiled xt660 camshaft kibblewhite valve springs ported head otr oil cooler 105.5mm 12.5:1 piston throttle body +2mm fcr style air inlet racing ecu with custom map and rev limiter @ 9000rpm Termignoni exhausts Termignoni headers WP 48mm upside down front forks WP rear shock fully adjustable Now im waiting for the front fork and rear shock to be fit and then the cylinder.... |
Looking forward to see the torque gains with the 12.5:1 piston.
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My expectations of Richards build is as follows the pipes used on the xt differ greatly from the ATV and may promote more mid rpm gains but this should be somewhat close Peak hp of 70 @ 7200 rpm making 50 hp by 5000 rpm Peak Tq of 54 @ 5200 rpm making over 50 tq from 4800 to 7200 :smilies0944: |
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So, Dan, very close to my estimate! All in all, it will be a very noticeable increase. But my torque won't drop away from 5000rpm like it does with the standard cam......I will be gaining loads of torque over my current spec. at 7000rpm as well!!! The trade-off will be a slight loss of torque around 3500rpm, maybe 6ft/lbs, against my current spec. which has 42ft/lbs @ 3500rpm. (standard 39ft/lbs@3500) However, this is all guesswork.................... Whatever it says on the dyno, I will be looking at around and about a 50% increase in power and 40% torque over standard. (I will use a different dyno to set it up, and go back to my original dyno for the power run comparison.) These figures should equate to a gain from my standard bike of 44hp-68hp = 24hp, and 42ft/lbs-57ft/lbs=15ft/lbs. And from my bike as it is, with DNA Stage 3 Airbox, PC111 and CC exhaust, 49hp-68hp= 19hp, and 46ft/lbs-57ft/lbs=11ft/lbs Just doing the Stage 3 airbox and Cans made a huge difference, so this is going to be alot of fun! |
part were shipped last week, hope you receive them soon!
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Thanks Dan!
As far as the ECU tuning goes, I am sending off my ECU for re-flashing to Piasini in Italy. Kev and Zaburtante have very kindly offered to send their ECU's as well, so that Piasini can see any differences between each ECU. |
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Nice numbers, you should know as you have modified enough of them.:partyondude: |
a quick update...wow time flys by!.
The engine has just been sitting in my garage for months now, but i have been running fairly soft knobbly tyres and doing a fair bit of offroading, so i have been reluctant to use my new motor, as it will probably wreck the tyres. however, after the HUMM in Spain next week, I will be putting back my road tyres.....and installing my demon engine! I have been running the Piasini ECU with no issues, the timing is advanced 3deg, rev limit upped to around 8500-8750 rpm (from 7200rpm), and the fuelling altered. So, hopefully some news in the next couple/three weeks when the engine is in, and when it's dyno'd. Hopefully get my offroad tyres back on soon-once I am used to the new engine |
We are all waiting. :bounce016:
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xtx 734cc
Hi, I have been chatting to Kev about these conversions as i maybe after this sort of mod to gain more power. I'm down in sunny Sussex and see your from the south. Could you let me know a little more about the places you got the machine work done and where the parts come from. Also costs.
Thank you Chris |
how is it going richard? your projekt sounds intressting!
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