Recommendations for Throttle Screw Position and CO Values Please

[RogerJ]

Hello All! I have gone through the threads related to throttle body screw positions and getting acces to the diagnostic mode to reset the CO values to try to ease off idle stumbling, walking speed performance and quicker and smoother response under load. My unit is a Euro Spec model and it lives in a hot climate by the sea at sea level (Mexico)l. It uses Pemex Premium 92 octane the only fuel available. It has the usual rumbling at 3200 to 3500 rpm and still has a rumbling vibration in the 4000 rpm to 4800 rpm range under load.

Continuing to look for relief from the vibrations, especially in the 4000 to 4800 rpm range I went to my dealer yesterday. We set the throttle screws to the 3/4 CCW out from stop position and reset the CO values to +6. This was based on my reading of what Jaxon and Blue Eyes did way back when before their bikes were more heavily modded. I assumed that Blue Eyes must be at sea level more or less and Jaxon too. Colorado values for CO didn't seem to apply here. My bike is stock.

The tech said that at delivery, the throttle screws were 1/2 CCW out from stop and the CO values set at 0. He on his own earlier had set them to 1 1/2 CCW out from stop. The CO values for each cylinder were set at zero. That setting didn't resolve the vibrations in either of the rev ranges mentioned above.

The tech said that in hot ocean coast climates like this one it is difficult to get the motors to run properly. That is why he had set the screws out to 1 1/2 CCW turns. He said that on the motorcycles and ATVs they often have to open the throttle position screws much more than this and up the CO values to 10 or 15 or more to get them to run properly. Since the concensus of this Board seemed to be favourable around 3/4 and + 6 I opted for that.

Our discussion was that the rumbling and vibration areas I have may be related to a LEAN fuel mixture. So we opted to try initially the 3/4 CCW out and CO values of +6. I rode 220 km today and bike responds much better. Hasn't done that much for the vibration patches, especially in the 4000 to 4800 rpm range which is highway cruising range. Maybe a 10% improvement in the vibrations.

Question is.........does it make sense to try wider open throttle screw settings? In particular, moving beyond the 1 1/2 CCW turns out from stop by adding another l/2 CCW turn out for a total of 2 turns out which the tech was suggesting? Any considered suggestions about the CO values? Leave them at +6?

All thoughtful advice much appreciated from those who have done this modification and who may be in similar operating environments. ::003::

 

[jajpko]

Hello All! I have gone through the threads related to throttle body screw positions and getting acces to the diagnostic mode to reset the CO values to try to ease off idle stumbling, walking speed performance and quicker and smoother response under load. My unit is a Euro Spec model and it lives in a hot climate by the sea at sea level (Mexico)l. It uses Pemex Premium 92 octane the only fuel available. It has the usual rumbling at 3200 to 3500 rpm and still has a rumbling vibration in the 4000 rpm to 4800 rpm range under load.

Continuing to look for relief from the vibrations, especially in the 4000 to 4800 rpm range I went to my dealer and yesterday. We set the throttle screws to the 3/4 CCW out from stop position and reset the CO values to +6. This was based on reading in what Jaxon and Blue Eyes I believe did way back when before their bikes were more heavily modded. I assumed that Blue Eyes must be at sea level more or less and Jaxon too. Colorado values for CO didn't seem to apply here. My bike is stock.

The tech said that at delivery, the throttle screws were 1/2 CCW out from stop and the CO values set at 0. He on his own earlier had set them to 1 1/2 CCW out from stop. The CO values for each cylinder were set at zero.
He said that in hot ocean coast climates like this one it is difficult to get the motors to run properly. That is why he had set the screws out to 1 1/2 CCW turns. He said that on the motorcycles and ATVs they often have to open the throttle position screws much more than this and up the CO values to 10 or 15 or more to get them to run properly. Since the concensus of this Board seemed to be favourable around 3/4 and + 6 I opted for that.

Our discussion was that the rumbling and vibration areas I have may be related to a LEAN fuel mixture. So we opted to try initially the 3/4 CCW out and CO values of +6. I rode 220 km today and bike responds much better. Hasn't done that much for the vibration patches, especially in the 4000 to 4800 rpm range which is highway cruising range. Maybe a 10% improvement in the vibrations.

Question is.........does it make sense to try wider open throttle screw settings? In particular, moving beyond the 1 1/2 CCW turns out from stop by adding another l/2 CCW turn out for a total of 2 turns out which the tech was suggesting? Any considered suggestions about the CO values? Leave them at +6?

All thoughtful advice much appreciated from those who have done this modification and who may be in similar operating environments. ::003::

I don't think opening the throttle body screws up anymore will do much for you. Just my opinion.
I had to put the PCV on and also did the rest of the mods to get rid of the vibes. You may be able to just put a can on and the PCV. Or maybe just the PCV
Changing the CO to a + 6 will just help off idle and does nothing in the other ranges.

I agree with the tech, that it is a lean condition, at least it was on my bike.

 

[X5]

My s10 is not euro spec.

I did not mess with the airscrew or diagnostic mod CO.

I added the Akrapovic exhaust and the rough patch was cut in half.

Based on objective Dyno data, my bike runs from perfect fueling to slightly rich.

There is no objective data, afaik, that the as and co mods help or hinder anything.

Perhaps start with factory spec settings? Since your tech adjusted things out of the box!

I live on the ocean in South florida so conditions here do not cause lean conditions per my Dyno.

 

[RogerJ]

Jim....thanks for the prompt reply. You may be right that the effect of air screw and CO "tuning" will be minimal and not enough without more (PCV alone, or, in combination with a new muffler) to calm the problematic vibrations.

X5....appreciate your pragmatism as well. Most likely the range of influence of these two modifications is very slight. The tech mentioned that most manufacturers do not test their new models in all of the climates they will encounter and come set up for "average" conditions. That is not tropical sea level coastal environments. Guess that is why the tech further opened the throttle screws from their original position based on "local knowledge."

Still wondering whether to pursue further opening of the screws, and/or altering the CO levels.

Jaxon, BlueEyes are you out there?

 

[Tremor38]

My s10 is not euro spec.

I did not mess with the airscrew or diagnostic mod CO.

I added the Akrapovic exhaust and the rough patch was cut in half.

Based on objective Dyno data, my bike runs from perfect fueling to slightly rich.

There is no objective data, afaik, that the as and co mods help or hinder anything.

Perhaps start with factory spec settings? Since your tech adjusted things out of the box!

I live on the ocean in South florida so conditions here do not cause lean conditions per my Dyno.

Yes, it seems like exhaust has quite an impact on the 'rough patch.' It's hard to get a bead on exactly how much impact because of verying rider sensitivity reporting anything from 1/2 gone to fully gone with a new can. I'm thinking the cat might be resonating a bit as well. I will be able to experiment with that abit as I have the Arrow Header and havent ordered a can yet. My first step will be 'checking for the rough patch' with the Diapason reflash >..I'm sure I'll actually be paying attention to vibes somewhere during that ride

 

[Blue_eyes]

Yes, it seems like exhaust has quite an impact on the 'rough patch.' It's hard to get a bead on exactly how much impact because of verying rider sensitivity reporting anything from 1/2 gone to fully gone with a new can. I'm thinking the cat might be resonating a bit as well. I will be able to experiment with that abit as I have the Arrow Header and havent ordered a can yet. My first step will be 'checking for the rough patch' with the Diapason reflash >..I'm sure I'll actually be paying attention to vibes somewhere during that ride

Vibes in your pants maybe.... ::025:: ::26::

 

[RogerJ]

Yes, it seems like exhaust has quite an impact on the 'rough patch.' It's hard to get a bead on exactly how much impact because of verying rider sensitivity reporting anything from 1/2 gone to fully gone with a new can. I'm thinking the cat might be resonating a bit as well. I will be able to experiment with that abit as I have the Arrow Header and havent ordered a can yet. My first step will be 'checking for the rough patch' with the Diapason reflash >..I'm sure I'll actually be paying attention to vibes somewhere during that ride

Tremor38.......I hear you on the new can helping. Ditto with the Diapason reflash. I am all ears for your experience when you get your ECU back. My issue is why do I have to spend $1500 to $2000 USD for new parts, electronics and so forth in order to get the bike to operate properly in cruising rpm range? That's YAMAHA's responsibility to make it operate properly in the normal highway cruising rpm range.

Any point trying further throttle screw positions and CO values? Or just let YAMAMA fix it and if they can't then look to getting a new ST?

 

[snakebitten]

I would expect Yamaha to fix whatever is broken. And to date, I haven't seen a single report where an S10 owner had Yamaha shaft them over a needed repair.

So I think it is a bit of a stretch to say Yamaha should "fix" it. In fact, many S10 owners don't feel the issues you are discussing are much of an issue at all.
(At least they don't bother me that much. But I am old and easier to please nowadays ;D )

The fueling on my KTM was far inferior to the S10. It took a considerable amount of effort to satisfy me. (And I LOVE it now)
But I don't think the 950 was in need of a repair or that KTM should fix it.

Having said all that, I also think it is more than fair that you would want to improve what you want to improve. But I bet it will be on your dime. Not Yamaha's.

Besides, Yamaha would probably tell you that they could make your bike fuel much better if they didn't have their hands tied. Those aftermarket cans, PV5, AT, and ECU flashes are all different methods of taking the treehugger hand cuffs off.

 

[jajpko]

@snakebitten, there are some bikes that vibrate much more than others. Not many, but some. I rode a demo a couple of weeks ago and it was a far cry from what I started with. If I had got that bike or one like it, I would never have complained about vibrations...

@RogerJ, there is not a good reason why you should have to pay for the parts to make your bike run right. But you probably will. I read on here that 2 bikes were bought back in South Africa. Don't know if that is true or not.

If you just put a PCV on, there is no guarantee that it will take away the vibes, but it would not cost that much, relative to buying a new bike. Also, Akra do not make the only can. It is a good one, but there are others as good in my opinion.

Try looking around for something used, you could save some money.

There is another member on this forum who had a bike that was very smooth. He put an Akra can on, and picked vibrations. This bike is very touchy and is easy to upset the balance with bad fueling.

Good luck on whatever you end up doing..

 

[HoebSTer]

My issue is why do I have to spend $1500 to $2000 USD for new parts, electronics and so forth in order to get the bike to operate properly in cruising rpm range? That's YAMAHA's responsibility to make it operate properly in the normal highway cruising rpm range.

Keep in mind, all the OEM manufacturers have to pass the regulations and emission levels set forth by the clowns in office!!!! They do the best with what they have to work with. I don't think for a moment any of the manufacturers would have a dip in performance if it werent for our level of standards here, just look at the euro levels. As far as I know, the Euro 3, 4, 5 and so on have been pretty close to the USA standards if not better in some senses.

 

[snakebitten]

@snakebitten, there are some bikes that vibrate much more than others. Not many, but some. I rode a demo a couple of weeks ago and it was a far cry from what I started with. If I had got that bike or one like it, I would never have complained about vibrations...

Good luck on whatever you end up doing..

That's a good point. If the difference between two bikes on the same assembly line have a stark contrast in some area, that would lend to the debate that Yamaha should address the issue as a "problem". And I also am willing to admit that almost any assembly line can produce a "lemon". (resulting in a buy-back)

But I have a gut feeling that some of the differences between two S10's would be viewed as very subtle by some and yet be felt as stark by others. Some of this stuff is subjective. My bike has various degrees of vibration at various ranges in the RPM scale. But they just seem so minor to ME. They might aggravate the heck out of the next guy.

Me and a riding buddy bought 2 KLR's on the same day from the same dealer back in 2006. Neither of us test drove either bike and we had no formal way of picking which one belonged to who. So at that first moment of ownership, there was no preference. But over the next 35,000 + miles we had the opportunity to swap bikes on several occasions. I ALWAYS got off of his thinking he got the better motor. It is just smooooother. Always has been. To me anyways. He doesn't feel the same thing. In fact, he always likes the way MINE rides. (I did some aftermarket suspension mods. His is bone stock)

Regardless, we both have different takes on what is better, worse, or even matters.

That probably explains my take on this subject. And I suppose I am biased by it a bit.

As I said though, it is fair for anyone to want to address whatever they feel needs to be addressed.

 

[RogerJ]

Thanks Jim for your clarification of this issue. This issue affects some limited number of First Edition bikes worldwide and some of the North American 2011 units as you know. Yes, 3 bikes in South Africa were replaced and the units sent to Japan for analysis. Would love to know what they found out about the causes of the vibrations in this rpm range. So far this knowledge hasn't trickled out anywhere to assist owners with vibration problems.

Snakebitten........just so you know I am not not talking minor inconvenience here or "thin skin." Riding in the 4000 to 4800 rpm range at highway speed makes the hand go to sleep within 60 kms and by 100 km or so the wrists ache. I have had lots of twins in my very long time and none of them have ever done anything like this. Funny how its always less serious when it's someone else's nerve and tissue damage. Just my 2 cents.

Thanks for all of the positive contributions. I know now that pursuing the throttle screw and CO value adjustments is not a profitable option for this type and level of vibrations. Case closed, over and out. ::003::