Jerky Throttle at low speed
 

Hi,
I recently brought a 04 XT660X after many years of owning 600cc four cylinder sports bikes.

I love it apart from one thing - the low speed throttle control is tough going.

I am well impresed with this forum, especially the advice from Kev and Captain Moto who have put a lot of effort into helpful advice.

Having read all the advice about Stage 1 & 2 Air Filters, Kev Fuel Mod, Air box Mod, CO1 adjustments I am almost afraid to ask such a simple question, so sorry if I have missed the point.

I am not really bothered about a Torque or HP increase, i just want to make the bike easier to ride through traffic at low speed.

Which of the mods give the best result for slow speed throttle control?

Thanks for any advice,
Lee.

Hi Lee

Can you look behind the left side cover on the bike & tell me what the last two digits on the Engine end with a 00 or 01? You can see why I am asking you to do this by reading this thread. http://www.xt660.com/showthread.php?t=8546

The best result can be found by using a Power Commander with a custom fuel map made for your bike & that is for all year XT660's, if you can afford it. The alternative is another fuelling device found in the modification index. Page right to the bottom & look under Surging http://www.xt660.com/showthread.php?t=630

Also look out for a in correctly adjusted or worn chain, a loose or tight spots in the chain make the XT feel like it is surging. Check the rear sprocket holder for free play, this is a common fault causing the XT to surge.

.

mate if you can get a st 1 and st 2 air filters and a power commander it sorts it like a dream, mine was a 04 had the same prob until i did this.

Kev,

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�.

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.

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.

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?

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).

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.

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?

Thanks again for any advice,
Lee.

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]

Kev,

Thanks for your patience with me on this, really appreciate your advice.

I have done what you asked and removed the ECU.
There does appear to be a white dot in the recess next to one of the mounting screws; to be sure I am making the correct assumption, I have followed CaptMoto advice on putting pics in a thread (hope it works?)�

Front of ECU:
http://i753.photobucket.com/albums/x...t660/Front.jpg


Rear with sticker:
http://i753.photobucket.com/albums/x...t660/Back1.jpg


Rear with sticker removed:
http://i753.photobucket.com/albums/x...t660/Back2.jpg


So, does this mean i have a remapped ECU fitted?

If so, then i am thinking about doing the following this weekend:
- Stage 1 & 2 filters (ordered already)
- Remove snorkel
- Drill Air Box
- Fit Kev Fuel Mod
- Adjust CO

If you could give me confidence that I have the remapped ECU fitted (hopefully you can see the pics) and am doing the right thing on the mods suggested I would be very grateful.

Thanks,
Lee.

That's good, you have the remapped 00 ECU. :angel2: That is the exact ECU that I run on my 07 XTX.

Your mod set up sounds good, let us know the out come.

Done Mods
 

Sorry for the delay, normal life matters got in the way of me getting round to doing the mods...

I have removed the snorkel, upped the CO from original of 7 to 15, fitted DNA Stage 1&2 filters, applied the Kev Mod and decreased the temp by 8C.

HUGE DIFFERENCE!!!! Thanks Kev :notworthy:

I still feel that the surging is there, but 10% of what it was before doing the mods.

I do have a couple of questions though. What is my best plan of attack for fine tuning? Up the CO some more or dial in a couple less C on the kev mod? Like i said i am really happy with the result but maybe i could improve?

Also, why did Yamaha manufacture the snorkel to be so deep in the airbox? Really cant work this out and cant understand how the snorkel restricts the airflow. Pic of my snorkel:

http://i753.photobucket.com/albums/x...t660/snork.jpg

Here is a pic of the mods installed:

http://i753.photobucket.com/albums/x...xt660/mods.jpg


Thanks again for all the advice on this forum, i am setting up a PayPal account to become a supporter on this site, it is superb!

Lee.