xr400 cam install

i just installed a 440 kit with a used xr400 cam. when i start it up it makes a loud ticking noise. it gets louder when you rev it up. can the decompressor cause this? the timing chain and tensioner is installed correctly, the valve lash was double checked, and it is not an exhaust leak. any ideas will greatly appreciated!

[FlyinRed]

Is there oil in it?
Did you drop a socket in it?
Did you use a break-in lube?
I noticed a modderate tick, while breaking mine in. It went away real quick. After break-in check the lash again.:huh

I just finished installing an xr cam and high compression piston in mine. It too is making a moderate ticking noise. I 've only had it running for about 10 minutes though. Tomorrow I plan on breaking it in. :D

[badass400ex]

do you have a ignition advancer? if so you dont get a acurate reading when you thing you are at top dead center your actualy not and causes the valve adjustment to be off

[FlyinRed]

You mean like an advanced timing key and not a rev box right?

pretty sure the 400 ex dosen't have a compresion realse so that out of it...just ride it and see if it goes away...all 4 strokes make some tickin

[barbwire44]

Originally posted by LRD TRX250R
pretty sure the 400 ex dosen't have a compresion realse so that out of it...just ride it and see if it goes away...all 4 strokes make some tickin


The 400ex does have an automatic decompression release it is located on the camshaft. Also note that when you adjust the valves make sure and turn the motor counter clockwise when aligning the timing marks, if you dont the compression release will be activated and you wont be able to get an accurate valve setting on the right exhaust valve.:devil

[papaw]

you should have eliminated your automatic decompression release with your new xr-400 cam.and the new cams do not like to babied when breaking in just don't go to crazy until broke in.

[Drtridr18]

Wouldn't the XR400 cam retain the decompression function since it came out of basically the same engine? Seems like it woud be pretty hard on things starting if it didn't decompres??

The xr 400 cam has decompression.

[papaw]

i believe its built in to the cam itself,i had to remove my automatic decompressor,and the plunger.

[Leo]

the XR and EX cam both have the decompression assembly on them.. it functions when the motor spins backwards (kicks back) not super important on the EX, but you wouldn't want to be without it on your XR :D

If you spin the motor over backwards when adjusting the valves it will activate the decompression assembly and you will wind up with a very loose R side exhaust valve, and a noisy engine! Always spin 'er counterclockwise (when viewed from the left motor case..)

Always use a quality cam assembly lube, and never let a new camshaft idle for any amount of time when breaking it in..

Leo