300 jetting advice for colorado??
 

Hey guys quick question, I live in southern Indiana and im going to taylor park, colorado july 24. 9000' plus evevation is what Im told. Bike is a 13 and has RB head mod and carb rework. What have you guys had luck with out there jetting wise? Ill take a few different sizes with me for back up but Id like to have the bike jetted before we leave hone. Thanks

General consensus (after a quick google) seems that a 165 main jet will get you by from 8000 to 13000, which can happen easily. I think the top of American Flag Mountain is 13.8k, if I remember right.

If you want to dial it in perfect then you'll need a pile of needles, pilots and mains and spend your entire trip messing with it.

When I was at Taylor Park I ran a 168, N3EJ (lean even up there on my 2000) and a 38 pilot. I'll say the pilot and main were acceptable but that fat needle interfered with definitive results. When I go back, I'm going to try a N3EW which I have on hand or order an NEDW because I am in love with the Suzuki needles. With this set up my bike didn't smoke a bit.. not even a little, so probably not a good thing.

Having said that, from what I gather the newer bikes with the AS2 carburetor might benefit from a leaner needle so the J diameter could be right on the money. I have to go at least one step richer on needle diameters due to my older carb design.

If you're looking for quick and dirty, I'd drop the needle a slot or two (depending on your current elevation?????) and go to a 165 on the main and call it good. Your pilot will be fat but that never seizes motors.

Col jetting
 

I have 2 300 gasgas with rb head and carb mods I run 42 pilot 175 main jd blue needle in the 2nd clip from the top good up to 12000' in summer

Thank you guys a ton! That gives me a good idea of what Im looking for. Any other pointers for going up there. I need to buy a enduro jacket with removable sleeves. Anything else?

I have a '14 300 with an AS2, "stock" head (it was replaced under warranty before it was started), stock carb, stock pipe/silencer, Mylers radiators, and stock 48T rear sprocket. I went to Taylor Park last year about that time running pump gas, number 8 slide, NEDW on second clip, 48 pilot, 168 main, air screw about 1.5 turns out, and map switch on "sun mode". It worked great but extended clutch work up hills after waiting for the riders in front to "clear" did get it to spit a couple of times so I would say it was a touch lean in the mid range. Frankinberg is very meticulous with his jetting so if you match his configuration (2011 300 with RB Mods, AS1, and 51T rear), use his specs as he has the best running bikes. Right now, I am running the NEDH instead of the NEDW since I am riding lower altitudes and I went to a 49T rear sprocket. As for other things, it will rain at some point in the afternoon and get cold when it does so something waterproof (or close) and warm dry gloves in your pack. Bring more fluids and some calorie dense food as your body will burn a lot trying to get used to the altitude. Also, please note that Colorado had plenty of snow this year and the trails will not be open for some time. Your dates should be fine but snow melt may linger later in the season than normal!

Eric

Can I buy just that blue needle from JD or will a suzuki needle work as well?

Ok, The group we are going with has been there a bunch so we are in good hands. It cooper bailey and his dad from texas plus a few others. They are hardcore some ive gotta get my big girl panties on for sure. Im an A level enduro rider so im looking forward to the challenge and trails.

Just remember with the rb design carb mod your jetting is a lot richer than stock I live and ride in Colorado don't go with the standard jetting you will be way to lean I have 5 gasgas bikes mine are all dialed in if you can find a jd blue needle you will love it

Just curious, why are a lot of guys going up on pilots at high altitude? Is the lower air density causing less fuel to be pulled through at idle RPMs?

With RB designs carb kit you have greater sensitivity on the air screw - I think stock setting is like 3/4 turns out with his mod. You need to ask what the air screw setting is for the RB design carb setup in colorado. Start out with same idle screw setting as well - (how many turns "out" and it should not be 'coil bound').

You will be able to adjust bottom end for very large altitude changes just turning air screw on RB designs carb setup.

Also - with some needles (and some that work very, very well) you run a richer pilot along with it.

jeff