2006 yfz450 question

[250rrr]

just bought one for cheap money for a spare....i know i know ...hahah

anyway, on the front brake side-top of the cylinder there is something missing (above the headpipe)....the oil is coming right of the the hole...is there a temp sensor or plug that goes int hat hole ??

thaks,mike

[kyledvor61]

oil return line going to the oil tank

[250rrr]

im gonna check it out today when i get home

[BakerRacing40]

i'd be willing to bet its your decompression plug. you can buy them online for 10 bucks or go to your local shop and probably pay 20 bucks. they are known to simply fall out.

heres a pic to give you an idea. not a great one though, thank to google lol
http://www.atvsource.com/images/article_images/press_releases/2004/thumpertalk/decompression_plug_03_small.jpg

[250rrr]

how does the plug stay in ? i felt around in the hole and did not feel threads ....
thanks,mike

im not positive without looking at it ....i looked quickly last night in the dark and when you turn the bike over i could feel air or oil coming out of the hole

thanks

[GPracer2500]

There's a bolt that threads into the side of the head. With the aftermarket aluminum plugs that are available, that bolt retains the plug. With the stock plug, I'm not sure if that bolt does anything. The stock plug may simply press-fit.

http://www.atvsource.com/images/article_images/press_releases/2004/thumpertalk/decompression_plug_02.jpg

Here's a bigger one, Baker. :)
http://www.atvsource.com/images/article_images/press_releases/2004/thumpertalk/decompression_plug_03.jpg



But you must have an '04 not an '06. At least the head must be an '04. Starting in '05 the YFZ450 head was a different casting that eliminated that hole. Notice in kyle's pic there's no bolt there. The casting is the same shape but it's all sealed up. That's how they are '05+.

Depending on the situation, I might have a beef about being sold an '04 engine advertised as an '06. The '06 engine got some meaningful improvements.