2000 450es knocking noise

I just bought this fourwheeler from a buddy of mine and he just rebuilt the motor step by step using the factory Honda service manual. He said that he was running it off straight silicone spray for about 5minutes he said because the carb wasn't any goodand he said there was no knocks of any sort. He said he did that just to build oil pressure. So i got it put a new carb on it and it fires right yup no problem. It ticks for a second up top then goes away when the oil pressure builds, then a slight knocking noise come in. It gets louder and louder and then it won't idle. It will stay running as i give r gas but as soon as i try to let it idle it dies. It sounds like it was in the front covers area or maybe around the jug area near the bottom. I pulled the front cover off to see if it was a timing chain issue and didn't see any problems. I made sure the clutch want binding or anything and no issues. I checked the batting in the case and it seemed fine. I can also hear the knocking noise when using the pull handle just turning it over. I know this was a lot and what ever help its gratefully appreciated. Thanks.