Okay I did numerous searches in the forums and didin't come up with anything for my altitude adjustment. I went to Big Guns website and still need some info. Here are the specifics.
04 Raptor 660, Big Gun Race series complete exhaust, 160L/165R, middle clip, stock needles, 27.5 pilot jets, 3 turns out on the screws, K&N filter, and 3/4 stock lid (cut off last clip area). My elevation is about 2500 ft in Las Vegas. When I let off the throttle I get some back fire and when shutting it off I'm getting a slight pop, sounds like the noise comes out of the airbox. Is it running to lean or rich at this altitude? Should I run it with the lid off and a filter to the crankcase. Big Gun isn't available on the weekends and it's to late to start playing with it tonight. Any thoughts? Thanks!

 

Are those jets mikunis or dyno jets? If they are dynos, you should be ok, check for exhaust leaks around the head. I would also make sure that the carbs are all the way in the boot. The pilot seems a bit big too, I think 25s with 2 turns out would be enough if you are running almost all your lid. Try spraying some engine starting fluid around the boots and if the engine revs a bit higher, you have a leak. To check your exhaust, just turn off all the lights in the garage and get a flash light and look around the head where the pipes connect. You might see smoke coming out, if not, try getting ur hand close and around the pipes, maybe you can feel the leak. Hope this helps!

 

The carb is seated properly and everyone at the shop here in Las Vegas said 27.5 pilots would be good just like big gun recommends on thier specs sheet. The head pipe looks good. The dyno jet info on my page is old just like most of my pics. Everything is keihen jets. Everyone recommends 3 turns out and stock clip setting on the third(middle) slot. As you know it's so much fun owning the only bike out there that takes an hour to re-jet. Thanks.

 

Also when I statred it up for the first time it made a pop sound and it was dead it would'nt start for a minute like I blew a fuse. Checked the fuses and they were good. Checked the positive cable on the battery and it looked like it had a black dirt ring around the terminal. I cleand the contact area around the battery and then tried it again, it started right up. Not sure why this happend? Can anyone explain this?

 

Go to www.thunderproducts.com and check out Dial-A-Jet. Also search Dial-A-Jet on the forum for my other posts.

 

Using 27.5 pilots and 3 turns out is too rich at sea level in the winter time for most pipes so you might want to check on that Try cranking the a/f screws in a ways, a 1/1.5 setup. I'm also not sure how/why you are or think you are using keihn jets in mikuni carbs, I dont think you're running FCR's on a piped stock machine. Mains seem rich for a very stock airbox, I would think something more in the 150/155 area for mikuni jets, 146/148 is the typical open lid setup for dynojets, so south of that for those.

Its not uncommon for the battery terminals to loosen up and allow the cable ends to stray from their connections, but a buildup of dirt or something else could cause a similar problem with a poor connection.

 

Sounds a little rich to me. Maybe, drop your mains down a size, and go back to the stock pilot. Also make sure your floats are adjusted correctly.