I'm taking a DR650 to S. America and expect to be doing some high altitude riding. Should I take replacement carburetor jets? I've been up to 12,000 feet in Colorado without issue but what about the high passes of the Andes?

Do you have the DR carby equipped with the extended fuel mixture screw? If so that would probably cover your needs in the Andes, though spare jets are always good to have handy.

If by chance you haven't rejetted or otherwise altered the carb/air setup, you can always remove the airbox cover at altitude, and/or the snorkel, for increased air flow....

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Jets are cheap, easy to carry. Bring a few spare jets ... but especially the Pilot Jet. Stay with STOCK SIZE Pilot Jet only. Pilots can clog up, hard to clear, so bring two spare Pilot Jets.

Main Jets: Depends on your set up. Bring one size smaller, one size larger, one stock size or size you currently use.

Do you have Stock Carb? Open Air Box? Stock exhaust?

If all stock, then leave current jetting alone. Just add the extended fuel screw as mentioned. Keep your fuel filters clean (one in petcock in tank, other is in metal inlet fuel tube into Carb) Carry 2 spares of this one.

You may want to consider an additional inline fuel filter ... which can help trap water. The first two filters will NOT stop water.

As suggested, removing air box side cover is a good way to bring in more air easily, but never run too long with cover off (dirty air filter). Lots of info on this on DR650 forums.

At speed, you may get surging with cover off. But WILL help at very high (over 12K) altitude. Do not lose backing nuts from side cover!

No matter what jetting you have you will LOSE at least 20% power once over 10K ft. (ALL motors lose power, even EFI) Even more lost over 12K or higher. But keeping the jetting lean (more AIR) will help smooth running, starting and even idling.

As mentioned, extended Fuel Screw is A MUST. Makes it easy to fine tune low speed running, idle and starting at high altitude. Then re-set to richer setting once down to lower elevation.

I would run a Twin-Air air filter. Flows more air than stock, will help at high altitude and improved overall performance. Good product!

In the Andes you will go above 12K quite a few times, but for the most part if your bike is now doing OK at 12K ... then should be OK. Just adjust the fuel screw for better idle and starting when very high. Will save on gas too! (big time).

Wow, thanks guys... more information than I can digest right now. I guess I need to do some research. I'm the 2nd owner and don't know what mods have been down if any to carb. It does have a K&N air filter, big gas tank with different petcock and fuel filters. I live at 7000' and have ridden to 12k' without problems other than the noticeable loss of power as expected. I will look into the things you suggested and become more familiar with this carb.

If you haven't seen it, this is a good primer on the DR carby.

The BST-40 Bible - ADVrider

For your South America ride, I would replace that K&N air filter with a Twin Air. K&Ns don't do well in prolonged exposure to dusty conditions unless you're using the proprietary K&N cleaning and oiling products.

I learned this the hard way. Ran a K&N on a KLR from California to Tierra del Fuego and by the time I got to northern Brazil was having all sorts of air cleaner problems. Tried every sort of conceivable (and available) cleaning product to little avail. The bike ran like crap.

When I got back to the U.S., I got a can of the proprietary K&N cleaning stuff and it solved the problem immediately. Didn't realize this when I set out, but validated it with subsequent research. Best bet is a Twin Air that can be easily cleaned with laundry detergent or other readily available products and reoiled with motor oil.

Good luck!

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