Bought new in 1985 a Honda 250 Fourtrax. Have used on the farm all these years. I have performed a tune up but she is still running rough. Took off the carb and cleaned it out really good. Seemed to help but still won't idle just right. Looking to by a new carburetor but have found out that the original OEM carb has been discontinued. I looked on line and there are many after market carbs available, some state they are plug and play and some are not. Can anyone recommend a carb that will be a factory fit? I was going to try and re-build the old one but the screws are seized up and almost broke trying to get them backed out. Thanks.