Sorry, you must be logged in to use the shoutbox!

Author Topic: Rebuilt Raptor Topend Noise Decompression Mechanism?  (Read 1238 times)

Offline tcoop212

  • Newbie
  • *
  • Posts: 4
  • Street Cred: 0
Rebuilt Raptor Topend Noise Decompression Mechanism?
« on: October 28, 2013, 07:50:32 AM »
I have recently rebuilt the top end on a 660 and it runs fine, but it making a loud mechanical clicking in the top. I have checked the valve spacing 2 times (the 2nd time it was spot on). I have been researching and  think it has something to do with the decompression mechanism on the cam being (180 off)? I know that cam has to be lined up properly, (I lined up the 3 dots correctly). The reason I think it has something to do with the de-comp is that it struggles to turn the motor over. It has a brand new battery and solenoid, and it still barely manages to get it to compress, as soon as it does it starts right up. I have uploaded a video on you tube of the sound, the link is below. Any help would be appreciated.

http://www.youtube.com/watch?v=lF_i-gUINf8

Tristan

Offline Peels

  • Sugar Cookie
  • VIP
  • Hero Member
  • *
  • Posts: 25444
  • Street Cred: 53
  • take the red pill and go down my rabbithole!
    • Email
Re: Rebuilt Raptor Topend Noise Decompression Mechanism?
« Reply #1 on: October 28, 2013, 09:35:00 AM »
I agree its most likely the decomp if the motor is running OK.. been awhile since I looked at a 660 motor though. Cant watch vid at work....

maybe the chain guide loose/floppin around? dunno




bet Mad Dog when he comes around will help you with this, guaranteed..  :thumbs:
Krandall: "peelz. I'll be real with you. As much as I hate on you for soccer, I really don't mind it"


Offline Mad Dog

  • Grand Masta Sexy
  • VIP
  • Hero Member
  • *
  • Posts: 1667
  • Street Cred: 24
Re: Rebuilt Raptor Topend Noise Decompression Mechanism?
« Reply #2 on: October 28, 2013, 12:04:16 PM »
decomp can be installed backwards, if that's what you mean.  Cam can be 180 off too, needs to have the lobes pointed down when you have the 3 dots up and in line.  Then there's always the question of "did you really set the timing correctly?"

Improper timing can cause starting issues as well.  The decompression mechanism allows valves to open when they normally would be sealed, bleeding off compression.  You'd get the same effect (valves open when they shouldn't be) if the cam is installed 180 out, if the valve lash is not properly adjusted on TDC of the compression stroke, or if the cam timing doesn't match up with the timing mark on the flywheel.

I'd re-check your timing and the decomp installation, and make sure your weights and keepers are not catching and are actually retracting the decomp pin.

Offline Peels

  • Sugar Cookie
  • VIP
  • Hero Member
  • *
  • Posts: 25444
  • Street Cred: 53
  • take the red pill and go down my rabbithole!
    • Email
Re: Rebuilt Raptor Topend Noise Decompression Mechanism?
« Reply #3 on: October 28, 2013, 01:17:08 PM »
MadDog is the 660 whisperer.  :lol:
Krandall: "peelz. I'll be real with you. As much as I hate on you for soccer, I really don't mind it"