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Kev · # 5 23-08-09, 09:48

Firstly, I am very conscious of the fact that this subject has been covered many times after reading through posts on the forum. I suppose that my ability to comprehend the vast information available here has been demonstrated by not initially recognising the problem as ‘Surging’.

Don't worry about that, we are all here to try & help out.

I am amazed at the technical knowledge available on this forum and you really are the man when it comes to the XT660; I think you know more about it than the clever folk at Yamaha who designed and built the bike.

Thanks, we have spent many hours playing with this bike & we are learning all the time.

The chain and sprockets look fine to me; I maybe should have mentioned that it has only done 2000 miles? It looks like it has been wrapped up in cotton wool for 5 years.

Nice find for you, low mileage

Done what you asked and the ECU part number is 5VK-8591A-00. So from what I have read the first owner did not complain to Yamaha and get the -01 ECU upgrade under warranty which was probably due to the fact that he never rode the damn thing!

So, I am slightly worried now – as I have the -00 ECU what is my best option?

Can you unbolt the ECU & see if there is a white paint dot on the back side of the ECU.

I think I can afford the Stage 1 & 2 DNA filters at about �100 but the PCIII on top of that is not affordable to me (as simo1432 recommends).

If your ECU is a 00 ECU with no white dot it will be quite hard to get a smooth ride. It can be improved with a fuelling device. If you are a handy man you can make your own or buy one for around 30 pounds. The fuel mod will definitely help, best is a Power Commander with custom fuel map which you have said is out of your range.

I have noticed that the problem is non existent when first riding the bike from cold, but then once the engine warms up it becomes a real pain at slow speed which spoils my enjoyment of what I think is a great bike.

Yoy are right the XT is rich in the warm up phase until it gets to opertional temp then leans out & causes the surge.

So, what do you recommend? The Kev fuel mod looks fairly straight forward and cheap but as I have the -00 ECU am I on a looser without the -01 ECU?

01 ECU is the best by far, don't give up as a fuel mod will improve things.

Thanks again for any advice,
Lee.[/quote]