Send a pm to Buhi http://www.xt660.com/member.php?u=36 he has a list of these, just ask him to give you the two type of ecu numbers otherwise he will link you to a yamaha japanese page that us westerners are unable to decifer.

My frame have 3 numbers more but it starts with 011

If Someone Get Those Numbers Of Ecu Please Post It Here Because That Is The Best Way To Check

My 04XTR changed ECU to 5VK-8591A-01 from 5VK-8591A-00.

In japan, ECU number of XTX(2005model) is old type. So, I think that, at this moment, old number ECU was rewritten to new program.

At this moment, both number are listed on Yamaha parts number list.
sorry, japanese site...
http://www.yamaha-motor.co.jp/parts-search/index.jsp

both costs 46620yen!

Therefore it is safe to say that:

The old and faulty ECU is : 5VK-8591A-00 whilst the new and corrected should be: 5VK-8591A-01

Thank you Buhi

Just to add fuel to the fire,I have just checked my ecu no. and it turns out to be the old one! But yet I don't suffer any of the symptoms.When I took delivery of the bike new, it suffered from slight surging ,so I did the usual. c.o.setting t.p.s and a.i.s. this worked wonders! Since then, Race pipe, k&n,snorkel removed, drilled airbox and more co2 adjustment, in my mind this has fixed the bike.No more probs whatsoever!(touch wood)

Thanks very much for this information, i have recently purchased a xt-r which has very bad surging and is impossible to hold steady revs in low gear. Bike was booked in for first service this Thrusday and have tried the co and tps changes with no effect i've now put it back to standard ready for service and will go armed with this paperwork.

Anyone have any idea how long the parts take as i'm guessing the dealer wont have stock of an ecu. Also should i expect any resistance or will the dealer simply look up the frame number check with yamaha and arrange to change it.

Thanks again for the info and the woderful forum which has been an enmormous help.

With new ecu the bike will surg too,if you bought it recently it probably have new ecu,changing ecu will not solve surging,my bike have new ecu and it surge,you got to do CO adjustment but it wont eliminate it,i had honda with 2 cilinders and it surged too if i were riding on very low rpm

This is exactly why our good Kev has had to resolve to designing a Modifications which is a MUST HAVE, just ask Skeeter, WheelieNice, tomr1992 and Laksof who had the pleasure of receiving one for free and their response was positive on all accounts.

Listen guys i don't make any money out of selling these mods i am only trying to help the community here, the Kev Mods are made and despatched by Kev in Australia, I can only suggest you hurry and buy one as there are 3 now available on ebay, bearining in mind that Kev can only make so many at the time due to his busy work.

Good luck

I've not experimented with the mods for fear of voiding the warranty, originaly the dealer told me all servicing has to be done by Yam Dealer or warranty was void, which i've since discovered is not entirley true.

I will get the first service out the way then start looking at the options, bought the bike as an 06 pre reg but by the frame number beggingin 011 i would guess its probably a 2004 build :(