Alditude sickness?

So I have a 1978 kz650 single pod filters and a header. I live in Galesburg Illinois(700ft.) most of the year and go to school in Peoria. My Dad works for rocky mountain national park in the summers so my family lives in Estes Park CO(8500Ft. where I live) in the summer... In Illinois My bike ran great. Here in Estes my bike wont even run. When I first got here I got it started and it ran untill it was warm then I couldn't get it to stay running. Now it wont even start, it fires but wont run. The guy i bought it from said he had 2 different sizes of jets in the carbs but I'm not sure... My idea is the carbs are not jetted right for the differance in alditude. If thats the case, then what size jets should I use here in colorado and what size should I use in Illinois? And where can I get different sized jets? I hope I explained my problem well enough:) Thanks for any help

You might want to shoot RonKZ650 a pm he lives in Colorado and has a 77 650 with pretty much the same set up as yours. Possibly he can point you in the right direction.

Most surely you are going to have to richen it up, try to richen it up with the fuel or air screw 1/4 to a 1/2 turn, raise the needle a notch and increase the main jet size, jetting is a adjust and test kinda thing, since everybike has so many variables, but the higher the elevation the less air you have, technicaly every 3,000 foot elevation change you should rejet for peak performance, also couple degrees advance on the ignition system would help also, that is my 2cents:side:

At 0-1000 ft your jetting for pods/4 into 1 should be about #110 mains and #17.5 pilot jets. Clip jet needle to 4th slot.

At 8500 ft, the jetting at sea level is very rich because of the thinner. air. With the same pods/4 into 1, mains should be 92.5, pilot #15. Reclip to 2nd slot on jet needle. You will have to adjust the mixture screw or air screw as well to lean the pilot mixture.

Great! Thanks for the help guys I'll give that a try and see how it turns out. What bike shop has the best deals on jets?

I can't tell you which company has the best deals because I buy all my parts from www.z1enterprises.com - their customer service and prices always make them my first choice.

Ok so I know it took a while but I got the carbs apart and found that I have 117.5(2 inside cylinders) and 117(2 outside cylinders) mains and #15 pilots. Does anyone have some old jets laying around? I don't want to buy the kits off z1 for 20$ but I will if I have to.

Mikuni sizes jets in increments of 2.5... 100, 102.5, 105, etc... The aftermarket clones of these jets may NOT have the .5 shown... in other words, a CARB REBUILD KIT containing the main jets for a Z1, which has #112.5 main jets stock, will have #113 main jets. The #117 and #117.5 mai jets are the same animal basically. Those jets are not going to give you the best performance; either power or economy at under 1K feet anyway... they are just too big. The jets you need don't have to be purchased in a "kit"... in fact you can't purchase them in a kit; you were looking at carb rebuild kits. Send them a note asking for four each of the sizes recommended. They won't be nearly as expensive as you think. I am pretty sure they sell main and pilot jets for your bike on a stand-alone basis.

Oh ok great I'll give that a try. Thanks!