automatic compression release

[gncc35]

for all you motor experts, i have a 440 w/ a magacycle x2 cam port job, 11 to 1 je 89 mm piston, edelbrock 38 mm carb, duncan fat boy exhaust. my question is what compression reading should i be getting, keep in mind that the megacycle x2 cam still uses the compression release mechanism, and what effect will this have on my compression reading. also can anyone explain how this mechanism works, is it rpm activated? can anything go wrong with it causing low compression or would it just not decompress like is supposed to, thanks.

[e gracie]

running true 11:1 ims kit and decked jug 32thou to suit giving me 185psi...also running mx re profiled cam

best i can do i am afraid did ask the same question some time ago worrying about me crank and rod but appears to be holding up quite well..fingers crossed so far.....

[gncc35]

Originally posted by e gracie
running true 11:1 ims kit and decked jug 32thou to suit giving me 185psi...also running mx re profiled cam

best i can do i am afraid did ask the same question some time ago worrying about me crank and rod but appears to be holding up quite well..fingers crossed so far..... what is a mx re profiled cam? does it still utilize the automatic compression release?

[gncc35]

can anyone answer my questions !!!!!!!

[oynot400]

You will not get a true compression reading with the stock decompression mech still in tack. It is rpm activated, as soon as it gets up to a certain rpm it will quit working. I don't understand exactly how it works, that is how it was explained to me. Most of the aftermarket cam builders have it removed. I think TC uses it on his cam though.

[Natertot426ex]

The release is used for starting. It bleeds a little of the pressure off to allow it to start easier and turn better so once it starts it doesn't do anything or affect anything.

[gncc35]

Originally posted by Natertot426ex
The release is used for starting. It bleeds a little of the pressure off to allow it to start easier and turn better so once it starts it doesn't do anything or affect anything. I know it is used for starting, my question was does someone have a similiar built motor that has the compression release still operable that has taken a compression reading, and what psi are they getting. thanks for any input.

Man for the #35 over all GNCC racer you don't sound like you know much about your quad!!!!!!!! j/k Don't worry you motor is holding 98% compression on a compresion test so your fine!!!!! You should have called Duncan on this since they are your BIG sponsor. hahahaha

[chavez]

look man it either works or is doesnt and if it doesnt take it to some one who knows how to fix it!!!!! you might try a pre race rebuild it always works for me

he took it somewhere to fix it and they told him it was fine. also gncc35 people might reconize your cam better if you call it a duncan racing cam (that's what they call it)

[chavez]

oh duncan racing cam why didnt you say so well here is you proble i think your air pressure in your tires might be low if you increase that it should run better

[ChadEXer]

I have the decompressor on my cam, it wouldnt even be able to start if I didnt, but Tom told me its impossible to do any compression checks with them. Its supposed to cut the compression almost in half at startup I think?

[gncc35]

Originally posted by ChadEXer
I have the decompressor on my cam, it wouldnt even be able to start if I didnt, but Tom told me its impossible to do any compression checks with them. Its supposed to cut the compression almost in half at startup I think? thanks for the help, you answered my question.