Have been on a BMW f650 but that had fuel injection but i had mate's with me on bikes with carb's ie Honda xr 400 and 650 not seen or been told of any problems from them and they went back the year after as well the xr 650 had been put to one side that time and he took his WR 250 running on a carb with no problems as well
My TTR was a bit weak and wheezy at around 8,000ft last year on the Vince in the pyrenees. It kept going fine, just needed to run a gear lower on some climbs to compensate. Mines got std pipe and jetting.
Maybe try some leaner needle settings first and see how it runs. If you're using the standard UK main jet at the middle needle setting I'd guess you'll be very rich at 10,000 ft. Above 8000 feet the leanest needle setting with a 137 main jet seems good (with a cut open airbox and twinair filter, stock US pipe). Below that (down to about 3000 feet), still with the 137 main, I'm good with the second-to-leanest needle setting.
Of course I'm riding the terrestrial US version, apparently the UK version of the TTR is amphibious, so you may need to keep your snorkel for when you get home :)
There was a thread from a guy in Colorado, which I can't seem to find. I believe he said he has 3 different jet/needle set ups for different elevations. Sounds like a lot of work to me.
Was in the Pyrenees just 2 weeks ago with a KTM 640 Adv carb'd, and I really don't think you need to rejet. That said it was still cold up there, and air density more important than it will be during the warmer days, but not that much difference IMO. You'll love this part of the world!
if you find it's running a bit richer than you would like & playing up...
try removing the air cleanner as long as yer not anywhere dusty...
that will lean it off a small amount...
Sorry to come late to the party! Done 3 VINCEs now on my TTR, along with Tiddler on his. We've not rejetted for altitude and both bikes ran fine. You may notice a small drop in power but you'll be concentrating too hard on the rocks and/or scenery to be worried by it, and a little richness might help the cooling in the warm temperatures? Of course, you could try pulling the snorkel or removing the airbox lid, as deep water is unlikely to be a big issue. Just watch the dust with the lid off - it might be a bit vulnerable to rear wheel thrown debris.
Don't worry, the TTR is not a finely tuned thoroughbred racer and will put up with pretty much all you can throw at it!
Ride safe,
Simon.
Thanks everyone for the advice, backs up what TTR guru Brian suggested (maybe take air box cover off) and my local garage (little rich will help with cooling).
Mine's been there for a week for about 4 years - agree with previous posts. You just about notice it's not perfect when you get up towards the snow line.
Mines not jetted great but ive taken mine too 5500m just by taking the air box cover off rather than the filter itself. Id just do that if you feel you need it!
