winter jetting

[mycat8urskidoo]

hello , if any of you read before, i was having some jetting problems (had 4 diff main jets)???, anyway, instead of trying to jet it out, i decided im going to get a set of stock pipes and run stock jets, i was wondering if i should run different jets in the winter time (yes i ride all winter, as long as theres not snow on the ground), i live in NW ohio, so the temp could be anywhere from 0 to 45 or so the next couple months

[KEITH KRAUSE]

Living in California, I'm no expert at REALLY cold weather and what real world effects it has on the jetting. It will run leaner though.
I think the stock jetting will be fine. I suppose if you wanted to be anal about it you could run a step (2.5) larger pilot jets in the winter and go back to stock when things warm up but that's probably not necessary.
Your biggest problem would be starting when it's that cold and a longer warm up time.
The choke circuit can be opened enough to get it started. That's what an adjustable choke is for. Don't open the throttle AT ALL as this will by-pass the choke circuit. Once started, you'll have to give it a longer time to warm up. Be sure the choke adjustment is correct.
I don't see the need to change jetting, however, you can adjust the mixture screws to fit your conditions. That's what they're for...fine tuning the pilot circuit. This will help in cold weather, at least for throttle openings up to 1/4 throttle. Just be careful if the screws have never been moved because they can be stuck and the heads strip easily. In warmer weather, you can re-adjust them if you like.
You adjust these screws using the "highest rpm method". Use a good fitting tool. If stuck, I always count and turn them in first until LIGHTLY seated and then clean out any factory sealant or crud with a straight pin. Then clean and use a drop of lube before backing them out. Some people STILL strip the heads so be warned if you think they need adjusting. Some people say the screws don't show any effect as they turn them. They should effect the rpm's. If not, that suggests the carbs are dirty or the jetting is wrong or you had the idle set too high while adjusting them.
Highest rpm method: Set screws to where they were before you removed/cleaned/moved them. Warm up the bike completely, set on centerstand. Adjust throttle cable per factory. Set idle to factory recommendation, probably 1,000 rpm's? Starting at any carb, slowly turn the screw until you hear the rpm's max. Fine tune it. Now re-set the idle to base/1,000 rpm by using the idle adjuster knob. Repeat to all carbs.

[KEITH KRAUSE]

Just to add...some here say a larger pilot jet will help with your situation. Makes sense.
I would still try mixture screw adjustments, if needed, first. If it's too hard to start, and the bike is in otherwise good tune, then I'd go with larger pilot jets.

[Steve]

Mycat,

I live in SW oHIo and also ride whenever possible. Coldest ride last year was not on the GS, though. 20 degrees for about an hour.

I did have the 650 out a couple of times and did not notice any difference in starting or running abilities compared to summer. It has a pipe and pods, I think the carbs have been jetted as it starts easily and runs beautifully. I have no idea what jets are in there, or what stock ones are for this bike, all I know is that IT WORKS. Works so well that during the summer it only takes about 30 seconds or so of running before it runs well without the choke. I like that. 8)

This year the 850 will also be running, so will have an opportunity to see how it does in the cold. Stock airbox, pipes and jets on this bike.

thegsresources.com/_scripts/gallerydispwnd.php?RegID=759

[SqDancerLynn1]

With winter weather the air will be more dense, will actuall make the bike run richer. But there is no need to rejet.

[bwringer]

My GS850G has been out in temps down to the mid-20s (F) and elevations over 8,500 feet with no hiccups and no jetting changes.

As everyone needs to do, I adjusted the idle mixture screws long ago for a richer mixture at idle (faster warm up, quicker starting, and more stable idle in all temps), but they do not need to be adjusted after that.

Two-stroke dirt bikes and sleds need to be rejetted for weather and elevation, but a GS usually does not. If you live and ride all the time at higher elevations, you might rejet slightly for that last erg of performance, but it isn't strictly needed.

[chef1366]

I'm from NE Ohio and rode all year long when possible and NEVER rejetted. As Keith said, just longer warm up time.

[KEITH KRAUSE]

With winter weather the air will be more dense, will actuall make the bike run richer. But there is no need to rejet.

Colder air has more oxygen in it. Same elevation. Humidity/higher elevations changes things.
He's wondering if he'll need to re-jet simply because of lower temps. If anything, he'll have to jet richer. Only problem he may have, if he doesn't change a thing, is harder starting.