Decompression Plug

5 replies to this topic
  • fatnugget

Posted February 25, 2005 - 01:41 PM


Hey guys I just did the YZ450 exhaust cam mod on my '99 YZ400F and I am liking it so far but I wanted to remove the hot start stuff off my bike to clean up the handlebars and save a little weight to boot. I was looking at the ones for sale on this site for 22.49 but I found these on ebay for 14.95. They look nearly identical to me. Had anybody tried this one?

  • grayracer513

Posted February 25, 2005 - 01:59 PM


That's like the variant of the TT plug that I had my son spin out in metal shop. The difference is that the TT plug uses the OEM seal for a decomp shaft and this one uses an O-ring in a groove cut into the plug. How well it works will depend on whether the O-ring has sufficient compression in place so that it doesn't leak later if the heat shrinks it. Ours worked OK. It's certain that it will at least stay in better than the stocker.

  • fatnugget

Posted February 25, 2005 - 02:07 PM


Based on that, would the TT one work better? I am not sure I follow what you mean by the decompresson shaft. After shipping the cost difference looks like it is less than $4 difference between the two.

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  • grayracer513

Posted February 25, 2005 - 04:22 PM


I would say that the seal used on the original TT version is a superior seal to a common O-ring, but it doesn't really have to do much in this case.

What I meant by a decomp shaft is the shaft you took out of the bore you want to put that plug in. The OEM seal for that shaft is the same type used to seal the TT plug. You can actually choose to leave the decomp shaft in place and not buy either plug, but you will have to be certain to keep the return spring for the shaft in place to keep the shaft out of trouble, or cut off the internal end of the shaft that lifts the valve. If you leave it as is, you would also need to remove it to reshim the right exhaust valve, too.

  • Satch0922

Posted February 25, 2005 - 07:34 PM


I wanted to remove the hot start stuff off my bike to clean up the handlebars and save a little weight to boot.

You mean decompression lever. The TT plug or the one on eBay will work.

  • fatnugget

Posted February 26, 2005 - 08:03 PM


Doh your right, my brain was ahead of my fingers, I meant to remove the decompression lever not the hotstart button. I ended up ordering the one of TT since they have provided this great forum for us. While that is on order I ended up grinding the the stock piece down and putting it back in until the new plug arrives.

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