Jerky in low revs

[Lausie_d]

Hey guys,

Over the last month or two, I've noticed my bike getting a bit jerky/juddery in low revs, particularly in gears 1 & 2. It seems to be quite noticeable when I'm holding a constant low speed, e.g. holding 30mph in 2nd gear (to avoid any probs with the speed cop who regularly hangs out by Buckingham Palace!!!).

I fitted the SC Project full system exhaust about 5 months ago but didn't fit the corresponding Air Filter or Air Fuel Modifier.

Is anyone else having similar issues?

I'm wondering whether its worth fitting the SC Project AFM - has anyone done so?

Alternatively, might it need remapping? Does anyone know of any London based remapping centres they could recommend?

Many thanks
Laura

 

[Eddieh93]

I'm not 100% sure if that would have a major affect on that, as a lot of other people have got the SC fitted/ other exhaust and have had no problems to report without the correct mapping, I think it would only have an affect if you put the air filter in, it would probably need re-mapping then.

 

[Gee]

Have you tried the '20min idle'?

Not sure if it works on the MT-07 ecu but wont hurt to try it. I did it after fitting my exhaust.

 

[johnny_pepperoni]

I also have the same problem, but I still have the stock exhaust.

Holding a steady throttle, usually in lower speeds, up to 35mph, in 2nd and 3rd gear, the cruising is a bit lumpy. I'm not sure what exactly is the problem, so I took it to the dealer, who also didn't know what to do with it.

 

[Ralph]

They run very lean at low power settings, if your dealer knows what he is about
and has the right engine management gear they can richen it up a little and
that should cure it at least it did on mine. Also "and I have not done this but will
next time I have the plastics off" you can move the intake temp sensor from
were it is under the front of the tank in a hot place to behind the air grill on the right
were it's cooler and so the bike runs a bit richer or so the thinking goes.

 

[Noggie]

This might be a shot in the dark, but have you checked your chain slack? Just a thought since it has gradually appeared.

Also, did you have a proper first service done? With throttle body synchronizing, or just an oil change.

 

[Simoncrp]

I have the same issue to an extent, that when i am keeping the throttle at a constant speed, the bike surges very slightly as if i am twisting the throttle, even though i am not. But i am due for my 600 mile service next week and my chain does look quite slack. So we'll see what happens afterwards.

 

[Lausie_d]

Thanks for all the replies and tips guys.

My chain slack seems ok. I clean, lube and check it every 2-3 weeks so I don't think thats the problem.

Gee, I haven't tried the 20 mins idle trick, but might give that a go.

Ralph, moving the sensor sounds like a good idea too, just wish I'd have done it when I last had the fairings off, such a pain to take them off again!!

Thank you all again, I shall keep you updated!

 

[addy]

I've noticed the same thing but it doesn't do it all the time. It feels like the bike drops in power for a split second and you hear the revs drop a little bit and seems to sort it when I increase the throttle a tiny bit.

-Bike is fitted with an akra titanium.

 

[Ralph]

Just re read the org post, doing a steady 30 in second is not something I ever do, I am ether accelerating
or slowing at that speed at a steady 30 I would likely be drifting along in 4th or even 5th and would drop gears
to accelerate, under those condition mine is smooth, if it ever stops raining up here I will see what mine does at
a steady 30 in second, it's doing about 4500 rpm in second at that speed so the slightest movement of the throttle
will be felt and the throttle is quite light on this bike, though I still suspect it is due to the bike running slightly on
the weak side.

 

[addy]

I forgot to say in my last post that I noticed it in 3rd at 30mph and even then its only happens occasionally. Only time I would be in 2nd at 30mph is if i'm in some traffic filtering and quickly accelerating.

 

[sdrio]

Thanks for all the replies and tips guys.

My chain slack seems ok. I clean, lube and check it every 2-3 weeks so I don't think thats the problem.

Gee, I haven't tried the 20 mins idle trick, but might give that a go.

Ralph, moving the sensor sounds like a good idea too, just wish I'd have done it when I last had the fairings off, such a pain to take them off again!!

Thank you all again, I shall keep you updated!

I've had mine off so often, I can probably do it in about 3 minutes flat now, both sides.

 

[Lausie_d]

Ralph - did I read that right...you cruise at 30mph in 4th or 5th gear? Blooming heck!! Most of my riding is a London commute, its rare I get 4th, let alone 5th - damn traffic lights!

 

[Ralph]

When I say cruse at 30 what I mean is if I am forced to run at that speed then I will
use the higher gears I don't cruse round the country side at that speed by choice,
It's likely that if I had to ride in London I would modify my style.
The nearest lights are 5/6 miles away in another direction I don't pass a fuel station
for over 30 miles and cant think were the nearest lights are.

 

[bobh]

I recently fitted a lambda sensor eliminator to my MT-03 to get rid of low-speed jerkiness. That big single is particularly bad at it. Early days, but it seems to have improved things.

The same seller lists one for the MT-07:

o2 Oxygen Lambda Sensor Eliminator For Yamaha MT-07 MT07 2013 - 2015 | eBay

Easy enough to fit, once you've found the lambda sensor in the exhaust and traced the cable back to the connector. Just unplug the connector and plug the gizmo into the cable to the ECU, to fool it into thinking the sensor is still there. You can either take the lambda sensor out completely, and plug the hole in the exhaust, or just tie the loose cable out of the way. Then if your bike is still under warranty you can return it to standard before it goes to the dealer for servicing or any other work so they don't have any wriggle room if something does go wrong..

 

[Ralph]

I did just unplug mine it did not through a code and seemed to run slightly better but seemed to use a little more fuel
left the sensor in place but plugged it back after a few days must do another test once the weather gets better.

 

[sdrio]

I did just unplug mine it did not through a code and seemed to run slightly better but seemed to use a little more fuel
left the sensor in place but plugged it back after a few days must do another test once the weather gets better.

Do you mean you just unplugged it and ran it without anything attached?

I might try it on mine, see if the dreaded cough/stall is affected. I'd be happy to give up a few MPG for that.

 

[Ralph]

Yep just pulled the plug apart it's a bit of a sod to get apart and behind the right alloy plate above the foot rest
I replaced it partly because I was not sure about how good it was for the sensor to be still in the exhaust but
a few days did not bother it or put any codes on the display. you can get plugs cheap but I did not bother.

 

[Lausie_d]

When I say cruse at 30 what I mean is if I am forced to run at that speed then I will
use the higher gears I don't cruse round the country side at that speed by choice,
It's likely that if I had to ride in London I would modify my style.
The nearest lights are 5/6 miles away in another direction I don't pass a fuel station
for over 30 miles and cant think were the nearest lights are.

Hahaa yes, I didn't imagine you would purposefully cruise around at 30mph.

30mph in 5th must be around the 2000 rev range - my bike would hate that!! It doesn't seem happy unless sitting in the midrange.

 

[Ralph]

Mine is smooth at that speed but I would not expect it to accelerate other than gently to
accelerate I would drop a gear or 3 depending on what I was doing I cant remember having
a modern twin and I have had a good few that can run at such low revs in high gears with
no sign of distress, just don't go whacking the throttle open at to low revs as that would not
be good for the engine.