Hi, just wondering is anyone has tried to run the engine with the compression release removed from the cam to avoid the noise associated with it. Is it an option or might there be balance issues?

 

me again, I was wondering if this has been tried before, I couldn't find it in the search. My son is complaining about the noise and says he's loosing compression due to the release not working properly. He's planning on pressing off the gear and removing all the components of the release then press the gear back on. I'm sure someone has thought of this before, and maybe tried it, I'd like to hear from someone who has possibly tried or heard of this before, and if it's fesible. Thanks

 

Well thought I'd say that my son removed the decompression mechanism from the stock cam without any problems. He had replaced the piston last month with an 11/1 ratio and had around 150pds of compression. After removing the decompresor from the camshaft now he's got constant 210pds compression and it runs great. It took care of the noise and also increased compression by 60 pounds.
I was a little worried about the high compression (possible) oil leaks, but he's broken it in and all appears fine. I'd would have thought this much compression would cause starting problems with the electiric start but no, it cranks even quicker than before, in about a half second or so. There is no difference as far as a balance issue, smooth as silk and the bike runs like a spotted ape. The only minor problems was air flow, we drilled 1/4" holes in the top cover of the air filter box, about 50 of them. Drew lines and spaced them out in a grid and they look factory. It helped tremendously.

Just wanted to let anyone know how it came out in case you were thinking of this mod.

 

I took mine out the last time I rebuilt my 400EX and have no problems

DWT

 

It is important to note the compression readings you are getting are faulted. The higher compresion is only becausse it is not releasing and allowing the motor to spin easy...more comp takes more juice to start...you don't have any more compression with the mechanism released at running RPM...all you have done is make the starter motor work harder(60lbs harder)

As for the noise its important to bring your motor up to tdc the correct way and not let the motor move in the opposite direction AT ALL. This is usually cause of the noise. Good luck guys

 

i don't understand why it is causing noise but it should run fine without the decompressor on it.

 

Quote:

It is important to note the compression readings you are getting are faulted. The higher compresion is only becausse it is not releasing and allowing the motor to spin easy...more comp takes more juice to start...you don't have any more compression with the mechanism released at running RPM...all you have done is make the starter motor work harder(60lbs harder)

I don't understand, you say the readings are faulted? I thought the decompressor simply released some compression at low RPMs for starts, however how can it release compression with no decompressor? If it spins over and shows 210lbs now, what's going to "release" the compression after it cranks? That doesn't really make any sense to me.