YZ400F AutoDecomp Mod

I have a '99 YZ400F that I have decided to keep and put some new life in it.

One of the mods I've decided on is the AutoDecomp cam.

I've read everything there is on here about it, but I still have a couple questions I'd like to get the answers too before I start.

I've decided to use HotCams products and would like to know if I need both Intake and Exhaust cams, or do I only need the Exhaust cam?

Also, does ThumperTalk still make the Decomp Plug?

I've looked in the ThumperTalk store and have been unable to find it.


Only the exhaust cam is needed for auto-decompression. Not sure on the plug, I just used a freeze plug.

I did the auto decompression mod to my 400 but used the 03 YZ450f exhaust cam. Works great. You only need to do the exhaust cam. As for the plug they are not made any more, I think I got one of the last onces they had in stock. You could take the decompression cable insert to a machinist and have them machine one out of a piece of aluminium for you. Other wise as suggest by aj_yz426, just use a freeze plug.

Good luck with the mod, it most certainly makes life a lot easier with the 400.

You can also just keep the decomp. lever in there and not use a plug. Keep it stock how it is, or grind off the lever portion and make it look more like a plug either way it will seal the oil out and work just as well. I ground down the lever and kept it the same lenght just made it round on the end, works great and looks good enough for me. It's not a show bike it's a dirt bike.

The freeze plug size is 18mm, BTW.

just need the exhaust cam, i did my 426 and its awsome not haveing decom lever

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