278 replies to this topic

[999nutta]

Hi. Desperatley after some advice please. I have had my bike 2004 900 33k miles, for 6 months now but hardly done any low speed/town riding.
I noticed a while back that it was lunging at slower speeds, so read about changing the CO values which i did. Tried the recommended 10 but ended up on 16 pair. Original were C1 13 and C2 27
Now my bike does 30mph at 3k revs in 3rd. It feels horrible. 40 in 4th 3k revs.
Higher gear and lower revs partly resolves but almost struggles. Lower gear higher revs better. But 30mph in second?
I want to love the bike but almost dread riding it now.
Even seems bumps at that speed makes things worse. Almost twitchy.
The TPS readings are 18 up to 101 with no missed numbers.
Stainless exhaust with baffles removed.
Sorry its a long waffle of a post but know that if you guys, or gals don't know, no one will.

[celticbiker]

Do you know if the air box mod had been done?
Also check the chain tension, it should be 50-60mm.

[muddy]

Airbox mod may help if it hasn't been done, but low rev fueling is probably the worst aspect about the 9er and Yamahas in general it seems.

[JBX]

Changing the mufflers for a more open pair result most of the time in a too lean mixture level.

Increasing the CO is ok, as well as what CB & Muddy said above.

Keep in mind the TDM is a big twin and it does not like low revs very much.

 

That said the low rev malediction is not always present : I don't have any trouble with it but I have the oem mufflers and I did some work with the airbox and the intake filter.

[Studley Ramrod]

Try increasing the throttle grip free play, might help with the bumps. Gonna try this myself as I also get the all or nothing twitch over bumps and I've got standard cans.

 

Of course you could always trade it in for a smooth running mk1 850.  Then again, I am biased. 

[999nutta]

Thanks for all the ideas. The TPS sensor was replaced under warranty.
The chain has about 50mm play
Airbox mod had been done. From looking at it the wires removed and capped
As for the throttle free play i have reduced it to nearly nil after reading somewhere to give it a go.
Wondering if the fuel mix is too lean. Have increased by 4 from stock on each side as a starting point. Does everyone else have their values same or different

[Studley Ramrod]

Reducing throttle play will increase twitchyness.  You could try increasing chain play too.

[fixitsan]

Try setting CO to original values and then adjust them again, both by the same amount. The original CO values are the factory calibrated settings to suit each injector and throttle body.

 

You had +13 and +27 , so try subtracting  '10' to give +3 and +17.

 

Also try adding 10, to give  +23 and +37.

 

Whatever you set them to, try to remember that C2 should be 14 more than C1

[TDMick]

Is there a way of increasing the friction in the twist grip? That might kill the all or nowt affect of bumps.

[999nutta]

Just out of interest what is everyone elses co settings?

[fixitsan]

I have C2 6 more than C1..... C1 = 14,  C2 = 20 ... I've had them up and down all over the place but not since changing the ignition timing by +4 degrees so I will be playing some more when i get the time. Since advancing the timing the ride has really smoothed out and low speed running isn't uneasy, it runs smooth quite low down now

Edited by fixitsan, 04 May 2016 - 08:04 pm.

[TDMick]

Just out of interest what is everyone elses co settings?

 

[Retro]

Just out of interest what is everyone elses co settings?

14/16.  Fortunately my TDM has run fine out of the crate.

Unlike the crap low speed fueling on my commuter XT (which has had the same TPS recall and updated ECU). The best improvement i've had was running CO at +100 with a noticeable decline in fuel consumption. Probably a compromise somewhere inbetween.

[frits44]

Hi. Desperatley after some advice please. I have had my bike 2004 900 33k miles, for 6 months now but hardly done any low speed/town riding.
I noticed a while back that it was lunging at slower speeds, so read about changing the CO values which i did. Tried the recommended 10 but ended up on 16 pair. Original were C1 13 and C2 27
Now my bike does 30mph at 3k revs in 3rd. It feels horrible. 40 in 4th 3k revs.
Higher gear and lower revs partly resolves but almost struggles. Lower gear higher revs better. But 30mph in second?
I want to love the bike but almost dread riding it now.
Even seems bumps at that speed makes things worse. Almost twitchy.
The TPS readings are 18 up to 101 with no missed numbers.
Stainless exhaust with baffles removed.
Sorry its a long waffle of a post but know that if you guys, or gals don't know, no one will.

I did the air box mod and I have my CO settings on C1 25 and C2 25.

I can drive my TDM 900a in low 2000 rpm in every gear without problems.

A two  cylinder engine needs balance so put the CO on both cylinders on 25 or higher if it stil is jerkey.

I wonder why many people has the CO to low it is not good for your engine.

 

You can read it on the JBX site by the comments that people are giving with there CO settings.

 

You can always change it the way you want.

 

Greetings,Frits

[frits44]

Very strange that  a two cylinder engine has different settings in the CO.

 

Cylinder 1 gets CO 13 Cylinder 2 gets CO 27 , here is no balance

 

Cylinder 1 is lean and cylinder 2 is rich very strange.

 

DO NOT DO THIS, CO settings needs the same number for his balance to run fine.

 

My machine runs fine with a fuel consumption of  1liter on 24 km when I am driving slow

When I am driving hard 1 liter on 19 km. 

 

If the two cylinder has no balance it will be jerkey.

 

Greetings, Frits from holland

[fixitsan]

Frits, what is your interpretation of the meaning of 'CO' as an anacronym ?

 

Is it CO for carbon monoxide (and therefore rich/lean mixtures)

 

Is it CO for 'Correction' ?

 

On any vehicle I have worked on, whenever an injector has been replaced it is supplied with a correction figure, which usually needs to be programmed into the ECU.

 

On some 3 cylinder Yamaha's with CO adjustment , there is only a a C1 and a C2 setting - do you have any idea why ?

 

It is said by Yamaha official documentation that C1 and C2 refers to 2 different rpm ranges.

 

Perhaps CO is interpreted differently for different bikes.

 

What do you think CO means ?

Edited by fixitsan, 05 May 2016 - 06:34 pm.

[fixitsan]

From the FJR service manual

"quote:"The on-board adjustment adds or subtracts a set time from the base injector duration (how long the injectors stay open during intake). At idle, this is a significant percentage of the total duration. At high loads, it becomes a much smaller percentage, so while it does still have a slight effect at full throttle operation, that effect is minimal. Each cylinder is adjusted individually to provide optimum mixture for each cylinder at low rpm.""

 

I know it isn't TDM, but it is Yamaha and it is CO on the screen.

 

If we assume it is gross CO level....then we have to ask how is that calculated ? The O2 sensor is of no use for that purpose and there is no inbuilt CO sensor.

 

In my mind i find it impossible to agree that the CO figure is an actual calibrated value for a specific CO level at low rpm for both cylinders *in exactly the same way* 

 

The manufacturing variations of fuel injectors are well known and they need to be trimmed individually.

 

My thoughts are that if someone believes that setting both cylinders to an identical value without making any measurements, and knowing that both injectors are likely to be metering different amounts of fuel for an identical period of time that they are opened for, then the question they need to answer is why does Yamaha repeatedly set these values to different amounts for different cylinders, across their range of motorcycles.

 

Sometimes the bikes leave the showroom with one cylinder's CO  higher than another, and another bike leaves with the values reversed. Are people quickly assuming that Yamaha or the showroom are making mistakes ?

 

This is what leads me to believe that they are trim/correction values for each cylinder's injector, because the small manufacturing differences between one injector and the next make a large difference at 5% throttle opening, but no big difference at 100% throttle.

 

The graphs I have seen show that the CO trim value does indeed only adjust AFR at lower revs. So while we have CO = carbon monoxide, we have no units by which to measure the changes with.

[Studley Ramrod]

CO is calculated via the use of a CO/HC tester which measures the CO density. According to the 9'er service manual, pages 3-19 to 3-20, the CO settings should be adjusted in conjunction with the use of the CO/HC tester.

[fixitsan]

CO is calculated via the use of a CO/HC tester which measures the CO density. According to the 9'er service manual, pages 3-19 to 3-20, the CO settings should be adjusted in conjunction with the use of the CO/HC tester.

 

 

Which is impossible to do, unless you weld rivnuts in the downpipes, or fit a non-standard exhaust....

 

The point i am making is that there isn't a corelation between setting value and CO volume per se.....for example a setting of 0 on one cylinder might produce 4% CO...can we safely assume that a setting of 0 on the other cylinder produces exactly the same 4% CO volume result ?   i don't think so.

 

For people who believe they should be set exactly the same *even when the factory set them to different values* ...... perhaps some explanation needs to be given why out of a range of 255 possible values, from -127 to +127 ,do nearly everybody's CO settings fit into the middle 40 or so range of values ? That suggests to me a non-random distribution, which suggests that the factory did measure the CO level and did make a correction, for each cylinder.

 

Therefore I don't see the need to become fanatical that both values must be the same, when we know there are manufacturing variances which virtually dictate that there must be differences in the correction value just in order to get the same % CO at the exhaust pipe

Edited by fixitsan, 05 May 2016 - 08:44 pm.

[fixitsan]

This is the result of somone's tests for an R6..... The blue line represents a setting of -50 and the red line +50 . The +50 value gives a tad more at the highest power level, but seems to introduce a not so good sag lower down, when compared to the setting of 0. This only proves that the ultimate difference is very small and in fact it could introcude more hestitancy if you go too high. Whether or not you would feel that hesitance is a different matter

 

 

I have to add that this test was at 5% throttle...the only way to see much of a difference. Easy to see at the end of the graph though, that the value giving the highest power is the one at (or nearest to...) a value of zero

Edited by fixitsan, 18 December 2016 - 06:31 pm.