Hey guys, new to posting on the site but I've been hanging around for a while now. I've got a couple questions to hopefully get some help with on my bone stock 2010 Scrambler that I recently bought brand new. I plan to ride some area trails in January, and it can get a little cold here in Wisconsin that time of year. It has a 155 jet from the factory, and the manual recommends a 160 under 40F. I've driven around the yard with the temp under 40F, there were no run issues and the plug looked ok, but that was on shorter time (not an all day ride). Anybody have experience with cold weather carb settings? I'll swap the jet if I need to because I don't want to blow it up, but I think these come a bit fat from the factory. From what my svc manual says, it's more of a PIA getting to the carb than it is changing the jet! Thanks in advance for the advice!!

 

welcome to the forum. it's not as bad with 4 strokes on the jetting as with 2 strokes with the colder temps causing engine damage. alot of peole i know don't change the jetting w/ the colder winter riding, but they usually don't ride all day even though i don't fell it would be that much differnt. stepping up one size as stated will give you piece of mind if you plan on doing alot of winter ridning at cold temps say in the 20's or below for extend time. i haven't done it myself, but i don't think it would be that big of deal to change out the main jet on a scrambler. this is just opinion of course.

 

I used to ride a lot in the winter. I never rejetted but I had to adjust the idle speed a little higher.

 

Only ones I really had to rejet down here were the two strokes that went up to 9-12,000 feet. On the 400's we went from a 200-210 main down to a 160 or so main jet. On the four strokes for the same altitude the jetting chart was like one size smaller than stock which wasn't worth the trouble.Plus most of the guys told us if they did experience any bogging if they went higher,they just popped the air box lid off and kept going. OPT

 

Thanks for the feedback guys! I ordered up a bigger jet today, but will do some local riding before actually changing it. We're in the 20s now, so I should be able to feel or see (in the plug) any A/F issues. Anybody have experience with the dial-a-jet systems?

 

Welcome to the forum.

 

I had the old dial-a-jet system on a 76 RD400 2 stroke years ago and wasn't too thrilled about it.Never could get it perfect versus just regular jetting changes. Possibly they may have improved over the years,but for a four stroke unless you go to extremes either in racing or altitude,you shouldn't need this. OPT

 

if you do put the bigger jet in, just watch it doesn't hog up on ya(meaning too much gas and not burning it) which causes fouling of plug and not running to it's peak. just another suggestion.