Help with Jetting for Denver Colorado.

[e30 gangsta]

Hello xs11 friends, I'm currently building another xs11 and I just recently moved here to Denver Colorado. I am curious if anyone has any suggestions as to where I should start/ballpark of jet sizes for this elevation. I am currently at 5280 ft.

The bike has a unbaffled 4 into 1,pod filters, and zrx carbs.

I was thinking 38 pilots and 130 mains to start, but I could be way off. Any help and or recommendations would be greatly appreciated. Thank you!

[cajun31]

Higher altitude means less air density, therefore less fuel is needed. ergo higher altitude means leaner jetting. For larger altitude changes, carburetor jetting adjustments may be needed. A rough estimate is one to two jet size reduction for every 1,000-foot elevation increase. Basically you are in a do and see situation. I have never had to do the adjustments. We do have some members from that area and can probably dial you right in should they see your post.

[DiverRay]

First, how was it running at sea level? That is your start point. If the setup was running well, plugs tan, I would go down just 2 sizes on the main and one on the pilot. Carbs DO auto adjust to some degree, and you don't want to go too lean, and then ride down at 2,000 feet. That is a good way to have problems. I've taken my XS1100, tuned for sea level, and done the Colorado rally with very little problems.

[e30 gangsta]

First, how was it running at sea level? That is your start point. If the setup was running well, plugs tan, I would go down just 2 sizes on the main and one on the pilot. Carbs DO auto adjust to some degree, and you don't want to go too lean, and then ride down at 2,000 feet. That is a good way to have problems. I've taken my XS1100, tuned for sea level, and done the Colorado rally with very little problems.

Unfortunately this one has never ran since I've owned it. ( New build ) That's why I was asking to see if anyone on here lived in the area, or had a good idea as to what jet sizes I should start off with while running these zrx1200 carbs.

[DiverRay]

Bones lives in the area, and runs the carbs on his XS1100. Try and see if he can answer you, as he will be the expert. I would find out what the stock jetting for the carbs are, and drop 2 sizes on mains, one on pilot jets. Again, it's all guessing to start with, but you do need something that will get it running.
Here is something from another member, who is at sea level, about the vacuum line needed for the ignition. https://xs11.club/forum/modification...with-zrx-carbs

[Socer4m]

HI E30,,,,if you can get ahold of motoman,,,,,,Brant,,,,,he lives in Grand Junction, Co. and knows the xs carbs like a guru,,,,, Ray is right, just narrow the jets down,,,,,hope Motoman can chime in here, Mike in San Diego

[Socer4m]

just remembered,,,also a member,,,,",Bonz " who ran the colorado rallies for years,,,,had an xs with the zrx carbs,, also a good one who had exactly what you are going through, maybe get ahold of Bonz and pick his brain.....Mike

[motoman]

HI E30,,,,if you can get ahold of motoman,,,,,,Brant,,,,,he lives in Grand Junction, Co. and knows the xs carbs like a guru,,,,, Ray is right, just narrow the jets down,,,,,hope Motoman can chime in here, Mike in San Diego

Sorry Mike, not familia with the ZRX carbs internal workings. From Diver Ray's suggestions, his option would be a good starting point.

[e30 gangsta]

Thanks for the help guys. I dm'd bones hopefully he reply's back.

[cajun31]

I believe bonz is in the process of moving east. Might be a minute before he replies to you.

[e30 gangsta]

I appreciate that Cajun, did some more research gonna go with 45 pilots and 135 mains to start.