1990 Polaris Indy 500 running rough

Ok, so just this morning, I picked up a 1990 Polaris Indy 500. The engine has a couple little quirks, here's my best description;
The first two or three times I started it, it started right up, and idled well. I revved it a little bit, but never tried to move it.
The next time it started, it idled at around 500 rpm (warm, it should be 1900), and I tried to get it to move, but it would get to 2000 rpms, and just bog down.
Now, it needs the throttle held in order to start, and it will stall if you try to let it idle. It will not peak 3000 rpm. It will slowly accelerate to 3000, then just stop, you can hold the throttle all the way and it just sits at 3k.

Any ideas?

The previous owner had damaged the kill switch, so he had been using the choke to kill it (flood). The spark plugs do appear to be fine.

Thanks!

ok first remove the air filter clean it then take the carb off and clean allt he jets and wholes make sure its clean then try it again

Jay_Rod wrote:

ok first remove the air filter clean it then take the carb off and clean allt he jets and wholes make sure its clean then try it again

If that doesn't help, it may be a dried out crankshaft seal.

Could in theory be something else too - but I forget if it has them. Reed Valve (s)... I cant remember if thats a reed valve motor though...

But it does sound like this problem I had with my old Harley cart... the reed valve had deteriorated, which would only allow it to run when the throttle was pinned much like you describe... once I replaced it all was well. Essentially what you may be looking for is a vacuum issue. Seals, reed valves (if equipped) even a carb boot. Check all gaskets for leakage of all kinds.

My foreman did this and turned out to be a stretched or broken timing chain

Thanks guys. I'm pretty sure it's a drive belt.