Hey guys, i have been searching the site for info, but i just want to see if we have some newer info out there.

Im going to Colorado with 12 other guys the end of july beginning of august. I am expecting to have to rejet the bike. I think our house is at 8500' and some of the high passes are around 12,000' I will be buying the t-handle a/f screw, i cant remember what main jet i have in my bike its either a 128 or 125... I am thinking to just put the stock 118 back in and taking the kdx snorkel with me, i currently have the airbox lid on but no snorkel in it.

Anyone ride at higher elevations and know what their jetting is? Any suggestions would be good. Thanks.

 

Hey if you end up having to buy 2 screws I would like to buy the other one off you if possible. The only place I found to get them, you had to order 2. Or if you know of somewhere you can get just one I would love to know, thanks

 

No problem man, would save both of us some money. Ill let ya know when im going to order.

 

Cool, sounds good

 

EMS, I'm jetted for 1700' with a 300 cylinder, 128 main, 35 pilot, DJ needle 3rd groove, Kouba screw 2 turns out. During my CO trip last August, my bike ran very cleanly at all altitudes and only chugged up the last 200 feet of Imogene Pass which is over 13,000'. The bike even idled, although quite low, at the Pass. I tend to think that for the very short intervals at extremely high altitude, you notice little impact on the jetting that works very well at everything else...unless you live in Death Valley or such. But really, unless you're already jetted on the rich side, it may not be worth the trouble. Many think that when they go to CO or other mountain states that they will constantly be riding at extreme altitudes, and that's not really the case. In many of these riding areas, you're riding from 3500' to 9000' most all the time. Leaning out the jetting to work optimally at say 12,000', will adversely affect the bulk of your riding. Heck...everything's a compromise. Maybe we can resurrect the dial-a-jet discussion?

 

Good points. My bike i think is the same as yours but i might have the 125 main, and the stock cylinder on... Would you suggest i leave it alone? I have the big gun exhaust and the airbox lid on with no snorkel in it.

 

Yeah, I also have the open top airbox...or at least the OEM lid with a much larger hole...and a full Muzzy exhaust. If you want to experiment at all, trying leaning out your existing setup to the point where you find the "too lean" spot...without burning a hole in your piston of course...and stepping back up to that optimal setup. The "too lean" jetting will usually result in a slight stumble when cracking open the throttle and/or carefully listening to telltale detonation. Many believe in the school of thought leaning toward jetting that's a little rich. Frankly I think jetting that's just north of too lean yields crisper throttle response and better fuel economy.

For most people, optimum jetting just rich of too lean will work quite well for the high elevation trips to CO. I think we tend to over think the jetting requirements of high altitude a bit, and regardless of some of the controvery about CV carbs vs. cable pull carbs vs. dial-a-jet vs. fuel injection vs. magic pixie dust, optimum jetting at a reasonable "home" altitude works surprisingly well in CO with a CV carb.

 

I live in Colorado, currently in Golden but I lived in Crested Butte for 14 months. CB is 9000ft, and the riding goes up to about 12K. When I was there, this was my setup:

No airbox lid
118 main
stock exhaust
DJ needle, 2nd clip from top
UNI air filter
Kouba screw 2 turns out

This worked pretty well for that elevation, and down to 7500ft or so. If you have an aftermarket exhaust, you could definitely bump up the main. Another option is to leave your lid on for lower elevations, then take it off when you get up higher.

I'd say a 125 would probably be fine with an aftermarket exhaust, but if you are more stock I'd go to a 118. I tried bumping up my main for a while when I lived there, but it was very boggy in the tight stuff. Of course, gearing is a factor too. Lower gearing means you can run richer and it won't be as bad.

 

Thats great, thanks for the help. im considering just leaving it go and taking off the airbox lid to lean it out a bit... im going to get the kouba fuel screw though. I think i have the 125 jet in the bike.

 

Out of curiosity, where in Colorado are you going? Taylor Park area?