1980 wr 390 jetting

OK! got a 1980 wr 390 motor coming to replace the 1978 cr 250 motor,the 38 mil. carb has stock cr 250 jetting. will i need to change anything?? looking for baseline setting, going to cut & fit stock 250 pipe until funds become available

id say, dont mess with the carb, get it fired, see how it runs and go from that point..
has it arrived yet?

not yet! post office say's 3-4 weeks that's ok, alaskan's are used to waiting, like, for DAYLIGHT!!! just wondering if i should get jets now to avoid waisting our short season, 1000 ft above sea level,-55to 85 above, just joking, who the hell would want to ride in 85 degree weather

id start with an 81 main jet...and see what happens...if your carb was working good before with the 250, chances are it will work good with the 390.
FYI..i looked into 3 day shipping....was over 200.00....and UPS wanted 195.00 for ground..so the 86.00 parcel post was a bargin...you get a free winter, well spring jacket in AK as well.

thanks chuck, went thru the tech ref, jetting the same, cr&wr-250&390,is there any diff. besides the tranny? port timing,reeds? don't fret over shipping time, if they put it on the ferry it's 17 day's right there!