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Low Rev Jerkiness


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#1 Raa

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Posted 28 August 2019 - 09:55 am

Apologies if this has already been discussed to death - if so, please send me the relevant link.

 

I'm generally enjoying my recently purchased 2011 TDM 900....but there is jerkiness around 2500-3000rpm which I am finding more and more irritating, especially in traffic. Having read about the airbox flap issue, I set about disconnecting the brown/black wire in the ECU (https://www.tdm-yama...ex.php?page=AIR), only to discover that it had already been done! So it's not due to the airbox flap (i think). I have heard some say that changing the air filter can help - any recommendations for alternative filters, or other solutions? 

 

 

 

 



#2 Riggers

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Posted 28 August 2019 - 01:42 pm

There are a million and one pages on this forum on this topic mate, and everyone has a different answer to the problem. Some suggest remapping the ECU, some say 'you'll just have to get used to it', and others say etc etc etc.

 

On my previous TDM900 it had a Power Commander fitted when I bought the bike, which I kept when I traded it in for a newer 900. So I fitted the PC to my new bike and it made the problem worse!

 

Now I ride it stock apart from the airbox mod (which was done when I bought it) and pay really careful attention to rear chain adjustment because at 50 to 60 mm it can cause very bad jerkiness. I keep it on 50 rather than any slacker and  find it does help.

 

I'm sure there will be lots of other suggestions to follow.....

 

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#3 TDM4ever

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Posted 28 August 2019 - 01:50 pm

On my previous TDM900 it had a Power Commander fitted when I bought the bike, which I kept when I traded it in for a newer 900. So I fitted the PC to my new bike and it made the problem worse!

 

 

On my 900, fitting a PC (and doing a Dyno run) cured the jerkiness. So, there you go...  :blink:  :dunno:



#4 catsbum

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Posted 28 August 2019 - 03:33 pm

This is my 7th 900 recently purchased and the first where I have no jerking. No PC. 

 

Very Happy

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#5 Johnners

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Posted 28 August 2019 - 03:48 pm

I read somewhere on here that a k&n air filter can help a bit and experimenting with CO settings can also improve things. Dunno if that's true - my bike came with a k&n and runs fine at low revs. I suspect the previous owner did all the hard work in sorting it out. Lovely chap 🤗

#6 Norwegian

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Posted 28 August 2019 - 03:57 pm

My 2002 900 has no jerkiness above 2000 rpm. Did the airbox mod, no real difference. AFAIK no other mods. Somewhat digital throttle al low speeds, but no problems driving smoothly.

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#7 Robodene

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Posted 28 August 2019 - 06:37 pm

I did the airbox mod with pipe disconnection. Solution for me.
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#8 chrisr

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Posted 02 September 2019 - 10:30 pm

Airbox, k&n, chain adjustment, clutch and throttle adjustment, Powercommander and dyno and that’s all it needed! Perfect now.

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#9 Hombre

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Posted 03 September 2019 - 09:41 am

Blocked the vacuum pipe and completely removed the gubbins and vacuum actuator on top of the airbox.

  .

Fitted a trim to the resultant hole.

tn_gallery_11876_358_667470.jpg

 

Changed the CO settings by the dashboard buttons.

 

Pootles from just below 2,000rpm no jerkiness.

 

2004 model.  Your 2011 might be different.

 

***You could try running without an air filter just to check effect.  JBX site shows his filter modification. https://www.tdm-yama...t.org/?page=FL9

 

***and let us know.


Edited by Hombre, 03 September 2019 - 09:51 am.

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#10 TKH

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Posted 03 September 2019 - 10:45 am

Jerkiness is usually a little lower down. Other things to check are the CO settings and the throttle bodies. Assume you don't have aftermarket exhaust on it? As an interim measure, can you control it with the clutch? I have a device fitted to mine, cheaper than the power commander and you can set it up yourself.  But can't remember the name of it. Old age I guess.

 

Your bike might be a bit too new to benefit from the airbox mod. 

 

If you do your own maintenance I'd try balancing the throttle bodies first and tweek the CO settings. JBX has a very good site to help with things like this. https://www.tdm-yama...ex.php?page=CS1

 

I remembered! I have a Dobeck techlusion to manage fuelling. Needs recalibrating again though.


Edited by TKH, 03 September 2019 - 04:35 pm.


#11 howardsmed

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Posted 28 September 2019 - 11:03 am

Hi

 

The low rpm jerkiness is the lambda sensor trying to correct the fuel mixture. below 6% throttle openings and I think 2000rpm, the engine runs in what is called closed loop configuration/mode. This mechanism relies on the O2 sensor( lambda sensor) to adjust the mixture to close as possible to stochiometric ( 14.64:1) however the lambda sensor fitted to ALL Yamaha models is a narrow band sensor and this just cycles alternately between rich and weak trying to find the idealised setting, this is what causes the jerkiness, Yamaha Tracer and MT09 are awful in this respect too  

 

All Yamahas suffer from this, but a big twin will the worst of all, funnily enough the MT01 doesn't have this problem. BUT they offer a re-flashed ecu as part of the tuning kit for these engines

 

The solution will NOT be a different air cleaner element , it will make it worse more than better, you can adjust the CO settings on your dash, which will make it slightly better, but these settings adjust the open loop part of the fuel map, NOT the closed loop part

 

the ultimate solution is to re-flash the ECU, I am chasing various people to see if it can be done in the UK. A power commander will sort out some of the fuelling problems, but nothing will be a s good a re-map

 

my bike is a 2011 model .

 

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#12 thelodger

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Posted 29 September 2019 - 11:40 am

This is what they are like. I fitted a Dobeck tfi 1025 controller to my 2013  , which helped somewhat but not enough to stop me selling the bike. I think you have to get used to it or preferably ride around the problem by riding positively with good open throttle control. If you ride by anticipating the jerkiness , eg by closed throttle on a roundabaout, I'm afraid that's what you will get.



#13 Oldgit59

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Posted 16 January 2020 - 07:47 pm

This is my 7th 900 recently purchased and the first where I have no jerking. No PC. 
 
Very Happy


Do you know what is the setup such that it doesn't jerk?

#14 howardsmed

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Posted 26 April 2020 - 02:51 pm

Jerkiness is usually a little lower down. Other things to check are the CO settings and the throttle bodies. Assume you don't have aftermarket exhaust on it? As an interim measure, can you control it with the clutch? I have a device fitted to mine, cheaper than the power commander and you can set it up yourself.  But can't remember the name of it. Old age I guess.

 

Your bike might be a bit too new to benefit from the airbox mod. 

 

If you do your own maintenance I'd try balancing the throttle bodies first and tweek the CO settings. JBX has a very good site to help with things like this. https://www.tdm-yama...ex.php?page=CS1

 

I remembered! I have a Dobeck techlusion to manage fuelling. Needs recalibrating again though.

 

Do you know what is the setup such that it doesn't jerk?

I had the ECU re-flashed, it runs very well, extremely well actually. absolutely no jerkiness. the FI now runs as an open loop system reading its fuel data points from a map rather than the Lambda sensor "modifying" the fuel input at low throttle openings. The lambda sensor and its closed loop fuel injection is the root cause of low rpm jerkiness

There is a slight loss in part throttle fuel economy, as the bike now runs at around 0.98-1.05 lambda instead of the 1.10-1.20 previously. ( i.e. more fuel, same amount of air)  

cylinder engine

All Fuel injected engines tend to run weak part throttle fuel air ratios, it improves fuel economy and emissions, however on a twin ( with light-ish flywheels) it will tend to make it jerky. the trade off for smooth operation is decreased part throttle fuel economy.

 

it has all the usual air box mods, but I have dynoed all these before and after. fitting a K&N without adding more fuel will make it worse, much worse. a slight improvement in part throttle can be obtained from changing the FA ratios on the dash, this will NOT however change the fuel delivery when operating at anything more than tickover.

 

My bike will happily run around at 1500rpm in the higher gears without any problem.  

 

Samios Racing did the re-flash, Spiros who runs the firm is a great bloke, very knowledgeable

 

Howard



#15 chrisr

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Posted 26 April 2020 - 03:44 pm

Interesting - I sent the Ecu from my 2010 model and he said he couldn’t do it

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#16 howardsmed

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Posted 26 April 2020 - 07:14 pm

only the NON abs ecu can be re-flashed

I had mine done over last winter, the results are as he advertises, very good. a few have had it done. part throttle performance is splendid, the only downside is a reduction in part throttle fuel economy.  

I will rectify this by removing the base gasket over the coming winter. this will decrease the squish clearance, increase the compression ratio (but only to what it should be) which will increase the economy. ( first law of thermodynamics)  

 

by next spring the bike will have been tuned to the parameters that it was designed to be. correct compression ratio and pressure, squish, valve seats etc.

 

we will see what it yields

 

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#17 Alekre

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Posted 27 April 2020 - 04:46 pm

It should have about 100hp with flashed ECU?



#18 wicklamulla

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Posted 27 April 2020 - 06:43 pm

It should have about 100hp with flashed ECU?

 

 

i doubt it will be as much as that at the back wheel.


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#19 TDM4ever

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Posted 27 April 2020 - 07:02 pm

It should have about 100hp with flashed ECU?

 

Never... Not just with a flashed ECU.



#20 Riggers

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Posted 28 April 2020 - 08:23 am

I've posted elsewhere that I've fitted a Booster Plug which enriches the mixture just off tick over. Unfortunately due to lock down I've not had chance to get out and give it a proper road test. I DID ride the bike around the block a few times and it does seem to be better but I don't know if that was just wishful thinking.

 

Once I've had a decent ride out I'll post the results up and let y'all know the outcome. If it works it's a cheaper option (£130)  than a PC, but if it doesn't it will be an expensive failure!

 

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