Cold Weather Making Bike Lurch

[fg1234567892000]

I have a 2003 GZ 250 and had noticed the bike was lurching slightly when running in the top ends of first and second gear. Knowing from other issues with the bike in the past that the previous owner was a sack of potatoes who cared nothing about routine maintenance, I took the bike in to have the carbs looked at. Sure enough, when I got the bike back they cleaned the carbs out, put in a new spark plug and new air filter. The bike ran better than ever.

Now that the weather is getting colder here in Iowa, the bike is having all the same issues as before, temperature dependent of course. Colder the weather=worse the issue. I've been riding it in 30-40 degree weather and it is hating every minute of it. But on a little warmer day (50-60) it works out of it pretty quickly and the issue is almost not noticeable. Is this a mechanical problem, or is the bike just prissy?

Thanks

[jonathan180iq]

You've heard, I'm sure, that cooler air is denser air. Cold, dense air is throwing off your mixture and giving you fits when it's really cold in the morning.

Being a carby engine, we are kind of just stuck living with it. If it were a larger bike, or had a more complex carburetor set-up, you probably wouldn't notice any difference. But since this is a single cylinder, simple carb engine, you just have to take it as it is.

It shouldn't be drastic, but a little bucking and running rough when it's cold is fairly common.

If you feel really adventurous, you can always adjust your carb to meet the winter climate. But most people just ride it out.

[Jvacustoms]

I had that issue arise this morning riding in 38 degree weather on my way to work. It wasn't that bad unless you are stuck behind someone and have to keep slowing and going it was when i really noticed that the throttle response was much jumpier, I just used the clutch to alleviate the bike of as much jerking. it seems to be the method I am gonna stick with.

But adjusting the carb doesn't sound that bad either now that I have experience with it the only issue in Georgia with that is that it is 38 when i go to work and 68 when i get off work... So i am just gonna ride her the way she is.

[jonathan180iq]

I should have mentioned that. Winter carb adjustments are something ideally suited for the Northen, colder climates.
However, in places like Georgia, worst care scenario is you will be running a little rich in the afternoon. That's not too big of a deal. You're only talking about baby tweaks anyway.

[Gz Rider]

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[Water Warrior 2]

The likely cause for the lurching is moisture in the air. At cooler temps the moisture tries to freeze in the carb venturi area and changes the shape of the venturi. This will mess up the fuel and air mixture process with results you don't want. A warm air intake system would solve the problem but a bit difficult to build for a motorcycle engine.

[fg1234567892000]

I appreciate the help everyone. I was just referring to the temp. of the air. The problem I think is that when I ride I don't really go far enough to really get the engine sufficiently warm, so this issue is something I am constantly dealing with. It has been my experience that when I have rode it for a longer time it works out of the fits eventually. I live in a city that has tons of mopeds, and some people run them all winter with seemingly no issues, so I was suspicious that my larger cc engine was having issues and not theirs. Glad to hear I won't really have to take it back to the shop.

Is there any fuel additive that might improve performance or anything short of actual carb adjustment that I can do to solve the problem? I know you can add some things to cars in the winter to make them run better in the winter.

[blaine]

IT wouldn't hurt to try some Sea Foam,or Berrymans b12 in a tank of fuel.
:cool: :)

[Gz Rider]

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[alantf]

I would think that riding with the choke on, & gradually reducing it as the engine warms up, is the way to go, rather than letting it idle on the driveway. :)

[jonathan180iq]

I would think that riding with the choke on, & gradually reducing it as the engine warms up, is the way to go, rather than letting it idle on the driveway. :)
And you would be absolutely correct.

Best thing you can do is choke and ride, even on the coldest morning. Sitting and idling is not good for these things.

[Gz Rider]

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[jonathan180iq]

Lubrication.

Not really heat build up, even thought that is a concern over longer periods of time.

The best way to get a bike warmed up is to ride it. The consensus is probably 100% over the wide world of motorcycle riding.
It's asking a lot for a small engine to keep itself going on a cold morning without revving it up, and getting all the parts moving.

If the engine isn't spinning fast enough, and it's cold enough, then oil isn't getting to parts that it needs to be getting to.
Use the choke to idle it up, slosh it through the gears one good time and you'll have a properly lubricated and warmed up engine in seconds, as opposed to minutes.

It's the same reason that car manufacturers don't recommend you letting your car warm up outside for 20 minutes in winter.
Oil pumps work well at idle, but they aren't perfect.

[Gz Rider]

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[mrlmd1]

You also are not charging the battery up at idle speeds and may actually be depleting the battery because of starting it and not recharging it. There is also much more oil circulating in a higher rpm range, not much at idle.

[Gz Rider]

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[Water Warrior 2]

When Lynda had her GZ she would let the bike warm up a bit while putting on her helmet and gloves. Backing off the choke a bit while it warmed a little was a must. After that she had about a quarter choke for a few blocks and all was well. Also pulling in and releasing the clutch a couple times tended to limber up the clutch plates which made the first shift into gear a little smoother. Everyone's results will vary due to temps and other conditions but it worked well with her bike. Try it you might like it.

[cayuse]

I'm in the same climate zone, WW, and my GZ warms up just like Lynda's.