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Just bought the bike last year and it has very low hours, just barely broken in. Haven't even taken it out, Anyways it was hard starting, finally got that taken care of, I've added the boyesen quickshot and that seems fine.

Problem is there is a very definate "knock" at idle that sounds like it is coming from the bottom end, and it will sometimes cause the engine to stall at idle. It is not constant, it happens perhaps every 15-30 secs, and veries. Could this be related to the transmission? Oil levels are fine and oil is clean. Both engine and tranny.

My friend thought it was running a bit hot too but we idled it for a fairly long period. Any input would be appreciated. We seem to have got the backfiring problem fixed as the pilot was probably a bit learn.Thanks.

Showtime,
Welcome. They all have a "knock" to them at idle to an overly-sensitive ear. Without having it started in front of me, I can not tell you if it's "normal". Do you have access to another CRF450? Try listening to other people's bikes like yours.

If my truck sounded like these bikes do, it would have blown up a long time ago... . Hope that helps...

Try turning up your idle, when my idle is very low on any of my 450's it makes the same sound you describe