hot cam with plunger issue

[03'400exrider]

I rebuilt a 400ex-- i put a hot cam and 440 big bore kit in. I know that for a stock cam you have the cam plunger and spring in the head. I left that cam plunger and spring in...should i remove it? or what will happen?

[Pipeless416]

remove it. hotcams do not use the decompression mechanism.

[03'400exrider]

ok..its in there now and seems to be running fine.....what effect will it have leaving it in there?

[Gibson]

What stage cam did you put in it? with a stage two, you need to remove the spring and plunger. Now with a stage three, you can still use the auto-decomp, but there's no need to. Plus you have to press the auto-decomp mechanism onto the new cam, so there's no need in going through all of that trouble. Just take the sring and plunger out;)

[03'400exrider]

I have a stage 1 in right now...what to do now?

[Gibson]

you need to take the spring and plunger out or you run a risk of them falling into your bottom end, and that wont be good

[03'400exrider]

i dont really understand how that plunger works..but what i really want to know is...does it have an effect on how the bike runs with the plunger is in but shouldnt be? ( im going to take it out, but I am curious.)

[drew416ex]

Originally posted by Gibson
What stage cam did you put in it? with a stage two, you need to remove the spring and plunger. Now with a stage three, you can still use the auto-decomp, but there's no need to. Plus you have to press the auto-decomp mechanism onto the new cam, so there's no need in going through all of that trouble. Just take the sring and plunger out;)

Where did you get this info? None of the hotcams use the decompression mech.

[03'400exrider]

is decompression mechanism a fancy word for cam plunger and spring?

[NacsMXer]

Originally posted by 03'400exrider
is decompression mechanism a fancy word for cam plunger and spring?

Those are only 2 of the 3 parts that make up the decompression mechanism. The plunger and spring go into a hole in the head itself while the last part is the circle-shaped piece that is pressed onto the end of the cam splines.

[Wheelie]

I have a Stg3/Stroker cam, and it doesn't use the stock compression release. As far as I know, none of them do.


BTW--Remove the spring and plunger, as stated before, it would suck to have it fall into the engine.

[03'400exrider]

I now understand what the decompression mechanism is. Thanks. But, I still would like to know what will happen if I leave the plunger in. Since my hot cam does not have the piece that moves the plunger, will it make a difference if I leave the plunger in, instead of tearing the top end off just to remove that piece?

[Wheelie]

Remove the piece, don't leave it in there.

[smokindw]

i had my local stealership install my stage 2 hotcam bout 2 weeks ago, how do i know if they took the plunger out??

[NacsMXer]

Originally posted by smokindw
i had my local stealership install my stage 2 hotcam bout 2 weeks ago, how do i know if they took the plunger out??

Ask them or take the head cover off and take a look.

[rideracelivemx7]

since no one is answering the question "what happens if i leave it in there" in the head almst directly under were the end of the cam were that ugly bulky looking thing is, there is a little cylindrical peice of metal that almost looks like the end of a pen, and directly under that is a little spring, you may need to use a small peice of wire or a reallllyyyy small screwdrive to get it out, but theres now nothing holding that down from falling out, it could fall down the right side of the motor and get lodged inbetween the chain and gear, eff that, thats some serious damage right there, so id suggest get crackin and dont you dare start iit up before you take it the 2 peice out