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Sprockets and Mods for High Altitude Trails

7068 Views 16 Replies 9 Participants Last post by  eskermel
Hey guys, I'm new to the forum and have already spent a good deal of time reading many of your great posts.

I'm new to the TW and am really loving it!

I live at 9,400ft in the central rockies of Colorado. I mainly will be riding on steep rugged single tracks and fs roads between 8,000 and 12,000ft. Id like to optimize my 2006 TW for high altitude steep trail riding. The bike will hardly ever go below 5,000ft in altitude or venture on big highways but still being able to putter around town is semi important.

I spend a great deal of time prospecting up in the mountains and essentially want to use the TW as a pack mule to areas that I don't want to or can't get my truck into.

My first issue is to address any re-jetting or air box mods that might be necessary. It sounds like most do just fine with leaving the stock jetting and simply adding holes to the airbox cover. If I'm spending most of my time this high in altitude, do I need to change out the jets or make other adjustments?

Horse power loss this high up is near 30%. I might be dreaming but in the end I'd like to be able to climb 60% grades at this altitude. I image that I would need to re-jet and change the sprocket gearing at the very minimum???

Would changing the sprockets give me noticeably more torque or climbing ability? What sizes are recommended and safe to run without risking damaging the motor or other components?

I am open to any and all realistic suggestions.

Right now, I'm stock. Hand guards, rear rack and skid plate on the way.

Thanks for all of your help!
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I read somewhere on here that a feller drilled small holes in the air box lid and used rubber grommets to plug them. When he would get in higher elevation he would start pulling out the plugs. I dont know what size jett to start with? Maybe around a 124-125 and go from there. If i was gonna be in the mountains all the time at higher elevation and wasnt concerned about running 60mph i would try around 55-57 rear sprocket. My bike ran ok up to around 9-10,000' before it started studdering but im sure it was still a bit rich at thoses altitudes but it made it the top of imogene pass which was all i was asking for with the stock jetting and 14/47 sprockets. Not ideal but we made it. Are you down around silverton, ouray, telluride area?
You have to take the shifter, foot peg and side case off of your motor to change the front sprocket. You also have to drain your oil or lay the bike on its side if you dont want to change the oil. That small of a front might wear your chain slide faster. I would start with getting it jetted right.
1 - 2 of 17 Posts
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