I have identical problem as svele
I"m srtuggle more then two years now with surging and hade no ideas aboute problem white ECU
Unfortunately I was yesterday find aboute this topic
my warranty has gone :eusa_wall::eusa_wall::eusa_wall:

and I"m sorry aboute my engish

Hi All
 

I just looked up the frame number of my bike as I have had some problems with it cutting out two times and being new to a big bike it is a bit scary when the engine just stops and you roll to a stop thank god it was not on a roundabout living in Milton Keynes,:crybaby2: and I have a very juddery throttle at low speeds my frame number ends in 4938 and the ECU has 5VK-8591A-00 both sound like they are in the bad ECU bracket! The bike is going in to be look at on 4/06/08 and the warranty runs out on the 20/06/08 so some advice on this so I don’t look to stupid with the mechanic at the garage.

Unless you live in a glass house, print the attached docs and hand them to your local AUTHORIZED Yamaha dealer they should know whats what and assist you, but you must do it while still under warranty

good luck

Well got the bike back and yamaha have told the shop not to change the ECU :smilies0979: but thay did play with it a bit and it runs abit better now.

Sorry to ask a stupid question, but in the attached doc it says range
XT660R Up to frame no. DM015-007858 XT660X Up to frame no. DM014-006257

I just bought a second hand XT660X Year of reg 2006 and its chassis number
goes DM015X5A000430 but that seems to be the range for the XT660R not XT660X. So is my bike good or bad ? Without having a part number for the ECU how do I tell ? :)

Being a 06 model you should be ok, to be sure what is your ECU number? The Asia Pacific XT's show a XTR frame number on a XTX for some reason, no one can tell me why.

5VK-8591A-01 so ok on that thanks :)

That's the good one, they are like gold very hard to find.:clock:

Kev Im a bit confused about JCM's Throttle Sensor Adjustment instructions.
He states before you start "It should be between 16 - 18." Then he goes on to say "Set the value to between 15 & 18." and you say you have found in playing around 16 is good. Mine is set to 16, so that would suggest its as good as it can be ? Any thoughts.

Basically the engine ECU needs a certain voltage range to know where the throttle is & between 16 & 18 it knows it is at idle. I find my best running postion is 16 for my bike.

One can set the TPS out of theses ranges & it effects the running of the bike. The higher the TPS reading lets say 23 the bike will produce more power but surges more on the cruise, at 14 the bike has less surge while cruising but does cut out at times.