biek sputtering in the cold weather (non GZ)

dannylightning · 09-30-2009, 11:11 PM

so its about 40 degrees out today and i went out riding. when i gave it just a little throttle it would sputter like it was not getting any gas or something. if i gave it more throttle it did not sputter. every time i went to ease on the throttle after slowing down or gear change i got sputtering but only if i eased on the throttle. i think i heard a clicking sound come from the engine once or twice when it did that.

im thinking the bike does not like the cold but not really sure what the deal is.. never had this problem before. it was a 30-40 min ride each way so the bike was warmed up. when the weather was nice i never had that problem. any one have any similar problems

Water Warrior 2 · 10-01-2009, 12:51 AM

Next time that happens try giving it a little choke. Even when warmed up it might indicate a too lean mixture for cooler temps. This is just a wild a$$ guess but the only thing I can think of right now.

**jonathan180iq** · 10-01-2009, 08:30 AM

Poor running in cold weather means that you have a lean mixture. The colder, denser air is making your bike run like this because the proportion of air to gas is no longer in balance. This is why it runs better when you give it gas or, as Water Warrior said, you give it a litlte choke. When you have a lean mixture, it means you aren't getting enough gas and that you need a bigger jet.

If this is only happening while at idle, then you just need to turn up your idle jet a little bit. It didn't sound like you have any problems while at speed, so I'm banking on a very slight richening up of the idle screw. If you were problems at speed, I would enrich the main jet or the needle jet, depending on at what speed you were having the problem.

This should apply to every carburated bike on the planet.

For a little personal persepctive, I thought I had my jetting spot on from earlier in the season. But now that the mornings are getting colder, I've discovered that I'm just a tad rich. In my case, I don't think it's enough of a difference to consider rejetting the carb, but swapping out my main jet is so easy that I have a "winter jet" and a "summer jet". Hopefully, this slightly smaller main jet in the winter will also warrant me slightly better mileage for the season.

**jonathan180iq** · 10-01-2009, 08:33 AM

You may also just want to make sure your carbs are clean.

dannylightning · 10-01-2009, 08:56 AM

no problem at idle,, only while moving and only will giving it slight throttle. when i took it to my mechanic he said he thought it was running slightly rich. it smells a little rich, stinks up the garage quite fast at idle.

**jonathan180iq** · 10-01-2009, 04:43 PM

But it was running fine in warmer weather?

**jonathan180iq** · 10-01-2009, 04:44 PM

Have you ever changed the jet needle or main jet on the bike in question?
The bike was running totally normal in warm weather, right?

I'm just kind of thinking outloud.
If your jetting was pretty close to where it should be during the warmer months, a little weather change isn't going to effect you that much. If you were running rich for all these months, then the cold weather should have made it better, not worse. You need to run some carb cleaner through there or have someone look at them to see if they are gunked up. You also need to make sure that a vaccum hose hasn't come loose somewhere.

The sputtering and popping; do they happen while coasting to a stop? Or just when starting to take off? I mean, if it's only when you take off, then it DOES sound like you might be rich in the middle... but I just don't see how that could happen if you were running well in warm weather. If it happens while coasting to a stop, you are definately lean.

Are you sure you haven't changed anything regarding the intake or the jets that you just haven't mentioned?
If you ARE suddenly running rich, then check your airbox and make sure that you haven't sucked up a leaf or something, which would restric air flow and make your stock jet setting seem rich.

mrlmd1 · 10-01-2009, 05:58 PM

Didn't you change the pipes on the bike after you got it?

dannylightning · 10-01-2009, 10:54 PM

its got to be running lean, i stopped bye the mechanic today, he said some times a bike can run rich in the higher rpm's and run lean in the low rpm's if the carb adjustment gets a little out of wack. he said see what happens after you install the new air filter and if it sux bring it on down and thell either adjust the carb or call me up and tell me if its gonna need a jet.

what i have done to the bike so far is took the baffles out of my pipes about a week ago, (ran great till it got cold) and i put a k&n filter in the bike TODAY and took it right back out, just made it run like crap and i lost all my top end torque, I probably do need a jet, I figure if i got to jet the bike than i mid as well go all the way and get real pipes instead of running half ass debaffled pipes

I have not changed any thing else on the bike. its got to be running too lean or too rich, couldent be a bad spark plug could it. not sure what happens when a plug goes bad on only 2 cylinders.

the sputtering and jerking (not popping) only happen when im giving it a slight bit of throttle no matter what, taking off, after a gear change, let off the gas and than give it a little throttle again. seems to idle fine and if i give it gas at idle it seems fine too.

**jonathan180iq** · 10-02-2009, 08:18 AM

All of those little changes, like the baffles and stuff, leaned up your mixture just enough that it still ran fine in warm weather but now the colder weather is making it apparent that your overall mixture is not right.

Sounds like you need to just enrich the needle jet. What kind of bike is this? If it's a V-twin, you might want to take it into a shop and have them do that for you, unless you are real familiar with working on bikes. Taking the tops off of your carb can be intimidating for newbies. If it happens to be a vertical Twin or a big fat single, then you can totally do it yourself. Look it up on google. I can't think of a bike that exists that doesn't have at least some type of forum devoted to it with friendly people who can tell you exactly what you need to do.

To answer the question in your own mind once and for all, blip your throttle really fast in neutral. Just a quick flick of the wrist and take the rpms up towards 60% or so your maximum. If the needle "hangs" on its way down and then comes down slowly, you are lean. If the needle rises slowly and then falls below idle before coming back up to rest at its normal position, then you are rich. Again, this little test should apply to any carberated vehicle on the planet.

PS: Anytime you make changes to the intake or exhaust of a carbed engine, you HAVE to adjust the carb jetting if you want to experience beneficial results.

09-30-2009, 11:11 PM	#1
dannylightning Senior Member Join Date: Apr 2009 Location: akron ohio Posts: 893	biek sputtering in the cold weather (non GZ) so its about 40 degrees out today and i went out riding. when i gave it just a little throttle it would sputter like it was not getting any gas or something. if i gave it more throttle it did not sputter. every time i went to ease on the throttle after slowing down or gear change i got sputtering but only if i eased on the throttle. i think i heard a clicking sound come from the engine once or twice when it did that. im thinking the bike does not like the cold but not really sure what the deal is.. never had this problem before. it was a 30-40 min ride each way so the bike was warmed up. when the weather was nice i never had that problem. any one have any similar problems Login or Register to Remove Ads
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10-01-2009, 12:51 AM	#2
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	Re: biek sputtering in the cold weather (non GZ) Next time that happens try giving it a little choke. Even when warmed up it might indicate a too lean mixture for cooler temps. This is just a wild a$$ guess but the only thing I can think of right now.
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10-01-2009, 08:30 AM	#3
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Re: biek sputtering in the cold weather (non GZ) Poor running in cold weather means that you have a lean mixture. The colder, denser air is making your bike run like this because the proportion of air to gas is no longer in balance. This is why it runs better when you give it gas or, as Water Warrior said, you give it a litlte choke. When you have a lean mixture, it means you aren't getting enough gas and that you need a bigger jet. If this is only happening while at idle, then you just need to turn up your idle jet a little bit. It didn't sound like you have any problems while at speed, so I'm banking on a very slight richening up of the idle screw. If you were problems at speed, I would enrich the main jet or the needle jet, depending on at what speed you were having the problem. This should apply to every carburated bike on the planet. For a little personal persepctive, I thought I had my jetting spot on from earlier in the season. But now that the mornings are getting colder, I've discovered that I'm just a tad rich. In my case, I don't think it's enough of a difference to consider rejetting the carb, but swapping out my main jet is so easy that I have a "winter jet" and a "summer jet". Hopefully, this slightly smaller main jet in the winter will also warrant me slightly better mileage for the season. Login or Register to Remove Ads
	0

10-01-2009, 08:33 AM	#4
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Re: biek sputtering in the cold weather (non GZ) You may also just want to make sure your carbs are clean.
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10-01-2009, 08:56 AM	#5
dannylightning Senior Member Join Date: Apr 2009 Location: akron ohio Posts: 893	Re: biek sputtering in the cold weather (non GZ) no problem at idle,, only while moving and only will giving it slight throttle. when i took it to my mechanic he said he thought it was running slightly rich. it smells a little rich, stinks up the garage quite fast at idle. Login or Register to Remove Ads
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10-01-2009, 04:43 PM	#6
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Re: biek sputtering in the cold weather (non GZ) But it was running fine in warmer weather?
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10-01-2009, 04:44 PM	#7
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Re: biek sputtering in the cold weather (non GZ) Have you ever changed the jet needle or main jet on the bike in question? The bike was running totally normal in warm weather, right? I'm just kind of thinking outloud. If your jetting was pretty close to where it should be during the warmer months, a little weather change isn't going to effect you that much. If you were running rich for all these months, then the cold weather should have made it better, not worse. You need to run some carb cleaner through there or have someone look at them to see if they are gunked up. You also need to make sure that a vaccum hose hasn't come loose somewhere. The sputtering and popping; do they happen while coasting to a stop? Or just when starting to take off? I mean, if it's only when you take off, then it DOES sound like you might be rich in the middle... but I just don't see how that could happen if you were running well in warm weather. If it happens while coasting to a stop, you are definately lean. Are you sure you haven't changed anything regarding the intake or the jets that you just haven't mentioned? If you ARE suddenly running rich, then check your airbox and make sure that you haven't sucked up a leaf or something, which would restric air flow and make your stock jet setting seem rich.
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10-01-2009, 05:58 PM	#8
mrlmd1 Senior Member Join Date: Jan 2008 Location: Crawfordville, Florida Posts: 2,853	Re: biek sputtering in the cold weather (non GZ) Didn't you change the pipes on the bike after you got it?
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10-01-2009, 10:54 PM	#9
dannylightning Senior Member Join Date: Apr 2009 Location: akron ohio Posts: 893	Re: biek sputtering in the cold weather (non GZ) its got to be running lean, i stopped bye the mechanic today, he said some times a bike can run rich in the higher rpm's and run lean in the low rpm's if the carb adjustment gets a little out of wack. he said see what happens after you install the new air filter and if it sux bring it on down and thell either adjust the carb or call me up and tell me if its gonna need a jet. what i have done to the bike so far is took the baffles out of my pipes about a week ago, (ran great till it got cold) and i put a k&n filter in the bike TODAY and took it right back out, just made it run like crap and i lost all my top end torque, I probably do need a jet, I figure if i got to jet the bike than i mid as well go all the way and get real pipes instead of running half ass debaffled pipes I have not changed any thing else on the bike. its got to be running too lean or too rich, couldent be a bad spark plug could it. not sure what happens when a plug goes bad on only 2 cylinders. the sputtering and jerking (not popping) only happen when im giving it a slight bit of throttle no matter what, taking off, after a gear change, let off the gas and than give it a little throttle again. seems to idle fine and if i give it gas at idle it seems fine too.
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10-02-2009, 08:18 AM	#10
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Re: biek sputtering in the cold weather (non GZ) All of those little changes, like the baffles and stuff, leaned up your mixture just enough that it still ran fine in warm weather but now the colder weather is making it apparent that your overall mixture is not right. Sounds like you need to just enrich the needle jet. What kind of bike is this? If it's a V-twin, you might want to take it into a shop and have them do that for you, unless you are real familiar with working on bikes. Taking the tops off of your carb can be intimidating for newbies. If it happens to be a vertical Twin or a big fat single, then you can totally do it yourself. Look it up on google. I can't think of a bike that exists that doesn't have at least some type of forum devoted to it with friendly people who can tell you exactly what you need to do. To answer the question in your own mind once and for all, blip your throttle really fast in neutral. Just a quick flick of the wrist and take the rpms up towards 60% or so your maximum. If the needle "hangs" on its way down and then comes down slowly, you are lean. If the needle rises slowly and then falls below idle before coming back up to rest at its normal position, then you are rich. Again, this little test should apply to any carberated vehicle on the planet. PS: Anytime you make changes to the intake or exhaust of a carbed engine, you HAVE to adjust the carb jetting if you want to experience beneficial results.
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