'83 ATC250R Acceleration issues

[brianb83]

So, first a little background. November 2014 I was helping my cousin clean out his property because it was being seized, and his brother came and helped and ended up pulling out his 1983 Honda ATC250R which he had broken his collarbone on many years prior. Well, the last registration date was 28 years ago, which I assume is how long it's been sitting, at least. He gave it to me(completely free, even!) and it's all there, and with a little carb cleaning it started right up!

Maybe a week ago, I started it up and I tried popping it into gear(it has issues with this, it will give a lurch forward and die) and it went maybe a foot or two and started revving uncontrollable. Well, I hit the kill switch, and it just revved higher. Not knowing what to do, I hit the throttle and it stopped. What could this be, and how do I fix it? it's having trouble with acceleration, but that's the only rime it's done that with the kill switch. Thank god I wasn't actually riding the damned thing,

Also, completely unrelated, but the fenders (rear specifically) have seen better days, WAY better days. Anyone know where I can get these relatively cheap?

[yaegerb]

Sounds like an air leak to me. To rule out an intake air leak. Start it up and spray carb cleaner around the intake where it attaches to the carb and head. If it starts iding erratic, shoots to the moon or dies then you have an air leak.