Bike was sputturing at 120+ km this morning.. | GTAMotorcycle.com

Bike was sputturing at 120+ km this morning..

Veej

Veej

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First time it ever happened I was on the 401 in express at 120 + and the shadow starting sputtering on and off...never had this happen before...you think it was the cold? or just some dirt in the carb, when I slowed down to get on the DVP it stopped but that could be cause I'm at lower speed, so don't know it really passed.

It's a Honda Shadow with Carbs....
 
Emerald94 said:
Time to switch on the reserve perhaps?
Click to expand...

No that's the first thing I thought cause that's what it was like, but I just filled her up 2 days ago and only have around 75 km on the bike since, it's good upto 200 km, I think as emerald said maybe running to lean, so will put the idle up a bit, but is this normal in cold temperatures?
 
Veej said:
I think as emerald said maybe running too lean... but is this normal in cold temperatures?
Click to expand...
Yes.
Bikes these days are delivered right on the extreme limit of leanness - in July!
Come November, the cold dense oxygen-rich air can alter your mixture by almost one full jet size.
This will manifest itself by exactly the symptoms you describe.
I'm sure 9 out of 10 Ninja250s are gonna behave like this too (if you can get 'em started, heheh...)
Time to put a little more oil on the K&N?
Note: this leanness problem is made worse by 'performance' modifications, ie. replacement mufflers and/or airbox mods.
Lot of people change pipes (in July) and say "there, see? Runs fine - I don't need rejetting."
But come November, it seems their bike is actually running much leaner than they had considered...
Also, check your intake boots (the short rubber tubes that attach your carbs to the motor) and your whole airbox system for air leaks.
Leaks will induce leanness.
Gently snug up those clamps on the intake boots - especially if your ride is more than a coupla years old.
Very cold weather is an excellent time to run lean, as overheating will be mitigated!
So basically don't worry :^)
Just keep your hands warm (before it becomes a safety issue),
Regards
 
Gryphon said:
Yes.
Bikes these days are delivered right on the extreme limit of leanness - in July!
Come November, the cold dense oxygen-rich air can alter your mixture by almost one full jet size.
This will manifest itself by exactly the symptoms you describe.
I'm sure 9 out of 10 Ninja250s are gonna behave like this too (if you can get 'em started, heheh...)
Time to put a little more oil on the K&N?
Note: this leanness problem is made worse by 'performance' modifications, ie. replacement mufflers and/or airbox mods.
Lot of people change pipes (in July) and say "there, see? Runs fine - I don't need rejetting."
But come November, it seems their bike is actually running much leaner than they had considered...
Also, check your intake boots (the short rubber tubes that attach your carbs to the motor) and your whole airbox system for air leaks.
Leaks will induce leanness.
Gently snug up those clamps on the intake boots - especially if your ride is more than a coupla years old.
Very cold weather is an excellent time to run lean, as overheating will be mitigated!
So basically don't worry :^)
Just keep your hands warm (before it becomes a safety issue),
Regards
Click to expand...

Thanks...for the crash course in carbs and cold, I feel better knowing this is not abnormal. So I'll increase my idle a bit on the way home I guess.
 
Whens the last time you changed your air filter?
It might be clogging up and not getting enough air at 120 KMH.
This happened to my wifes shadow, replaced the filter and it it was good to go.
 
Please correct me if I'm wrong here but I don't believe increasing your idle changes your air/fuel mixture. To do that you turn in/out your fuel mixture screws located on each carb. Not something you want to do on the side of the road.
 
If it's sputtering when cruising at highway speed then this has NOTHING to do with ANYTHING related to the idle mixture or idle speed settings or anything else idle-related.

One person above got it right. Temperature a little above freezing and high humidity are a perfect recipe for carb icing. I had an old Honda Civic that was horrific for this, and my old Ninja 750 did it occasionally, too.

It stopped doing it when you slowed down because you either slowed down enough to let a bit of heat soak into the carbs and melt the ice, or the icing was contained to the main circuit in the carb and you slowed down enough so that it would run okay on the slow circuit in the carb and it so happened that the ice wasn't built up in that part of the carb.
 
Brian P said:
If it's sputtering when cruising at highway speed then this has NOTHING to do with ANYTHING related to the idle mixture or idle speed settings or anything else idle-related.

One person above got it right. Temperature a little above freezing and high humidity are a perfect recipe for carb icing. I had an old Honda Civic that was horrific for this, and my old Ninja 750 did it occasionally, too.

It stopped doing it when you slowed down because you either slowed down enough to let a bit of heat soak into the carbs and melt the ice, or the icing was contained to the main circuit in the carb and you slowed down enough so that it would run okay on the slow circuit in the carb and it so happened that the ice wasn't built up in that part of the carb.
Click to expand...

So I don't do anything?...also I don't recall this happening...does the carb icing go in hand with the age of the bike?
 
Carb icing won't depend on the age of the bike. It'll depend on the internal design of the carbs, which won't change with age.

Keep in mind that carb icing will only happen under very particular conditions of temperature and humidity. Temperature near or somewhat above freezing and high humidity, and only under driving conditions that are not leading to heat being conducted into the carbs (i.e. typically highway), and only when these conditions prevail for long enough for the problem to occur (because it takes a while for ice to build up). In city driving, the reduced airflow around the engine will normally let enough heat get into the carbs that ice won't form. If all the stars are not in alignment then the carbs won't ice.

It's most likely that you simply haven't encountered the particular combination of circumstances leading to carb icing before.

If you find that the sputtering occurs every time in cold weather regardless of humidity (note that when it's below freezing, there is normally not enough water in the air for icing to occur) then it could be carb jetting.

If it's icing, and it really gets bothersome, you need to get some heat on the carbs.
 
Brian P said:
Carb icing won't depend on the age of the bike. It'll depend on the internal design of the carbs, which won't change with age.

Keep in mind that carb icing will only happen under very particular conditions of temperature and humidity. Temperature near or somewhat above freezing and high humidity, and only under driving conditions that are not leading to heat being conducted into the carbs (i.e. typically highway), and only when these conditions prevail for long enough for the problem to occur (because it takes a while for ice to build up). In city driving, the reduced airflow around the engine will normally let enough heat get into the carbs that ice won't form. If all the stars are not in alignment then the carbs won't ice.

It's most likely that you simply haven't encountered the particular combination of circumstances leading to carb icing before.

If you find that the sputtering occurs every time in cold weather regardless of humidity (note that when it's below freezing, there is normally not enough water in the air for icing to occur) then it could be carb jetting.

If it's icing, and it really gets bothersome, you need to get some heat on the carbs.
Click to expand...

Cool...thanks for explanation...I guess all the stars aligned this morning....

It was quit weird...I would push to 140 and then when it stuttered I'd let it down to 120 and up again....to 140 then when it stuttered I'd reduce it again, so playing with the throttle helped it overcome the stuttering at high speeds..not sure if this sheds any more light.
 
macrider said:
Whens the last time you changed your air filter?
It might be clogging up and not getting enough air at 120 KMH.
This happened to my wifes shadow, replaced the filter and it it was good to go.
Click to expand...

I second this. Cheap to fix, probably should replace it anyway.
 
So last night on the way home the same thing happened and coming in this morning the same thing. If I go 135 km then it's fine but soon as I hit the 140 mark it starts.

I put the idling up this morning but that doesn't help (as everyone here mentioned but thought I'd try anyways.)

So the sputtering starts exactly when I hit the 140 mark anything less the bikes fine.

Regarding the air filter cleaning, I just cleaned it 2 -3 weeks ago it's a K&N lifetime filter which you clean with solution and then oil it and put it back in.

So is this still the symptoms of carb icing?
 
With this new information, it sounds more like fuel starvation. Check the fuel filter. If it doesn't have one, check the pick-up in the tank.
 
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