04 Yz450F blown decompression plug

3 replies to this topic
  • Toobold30

Posted June 07, 2007 - 05:14 AM


Hey everyone. Well another decomp. plug blown here on my 04 Yz450F. My question is this. If this plug blew out, i was undering the impression it would blow all the oil out. I started the bike this morning and still have a good oil level. By blowing this plug and still haveing oil showing on the stick, would you think my bike is still ok? Thanks eveyone.

  • 2wheels-drz

Posted June 07, 2007 - 05:44 AM


same thing happened me, i rebuilt mine after but i stress only because it was due. your bike is fine, it won't loose that much oil, mine lost very little too. replace with a TT decompressor plug, it is locked in will a screw and therefore can't blow out, and top up your oil. problem sloved. o and check for a blocked brether hose, thats what caused mine.

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  • Wyatt

Posted June 07, 2007 - 05:49 AM


All of the oil will not just blow out. The hole that the plug leaves is not a hole into a pressured oil passage. This would cause the oil to blow or pump out. It leaves a hole into the top of the head which is really not any different than the crankcase vent. It is in a worse location for a vent and oil will spray out during use. A little oil spray makes a big mess.

get the Aluminum plug and it will never happen again.

  • grayracer513

Posted June 07, 2007 - 07:50 AM


Say it ain't so! :thumbsup:

Seriously, the OEM plug is like plugging a hole by wishful thinking. Don't bother with another one unless you have to have something while you're waiting for the replacement.

What probably happened is that one of the metal clips that hold the breather tube to the frame got flattened and pinched off the tube. The build up of crankcase pressure popped the plug out. It also may have just fallen out.

Replace it with One Of These, or get an 18mm brass cup plug (freeze plug) at an auto parts store.

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