popping on decel, keep octopuss? adjust fuel screw??

9 replies to this topic
  • Brettv

Posted July 14, 2004 - 04:32 PM


my bikes pops on decel, a fair bit, the octopuss is suppose to help this right? to get rid of this should i be adjusting the fuel screw? or pilot jet? and if i take off the octopuss will it worsen the popping. sorry im not sure what pilot jet i am running, but i think it would be stock
cheers :thumbsup:

  • sjwr450

Posted July 14, 2004 - 04:49 PM


You did not mention if you just modified your bike to cause this. I would try the fuel screw first. If not go up one on the pilot jet.

  • Brettv

Posted July 14, 2004 - 05:13 PM


sorry, havn't tried it yet, just thinkin about it. thanks

  • The_Missile

Posted July 15, 2004 - 01:11 AM


try the fuel screw first. More than 2.5 turns
....bigger pilot

  • Hamish

Posted July 15, 2004 - 01:35 AM


before you do any of that check for exhaust leaks. If it didnt pop before and does now, it's not tune-up replated.

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  • The_Missile

Posted July 15, 2004 - 03:25 AM


Hamish, on that thought, if you blow out the packing of your exhaust, I guess it would create a freer flow and the bike would run slightly leaner and hence poppng ??? Also the same if there is a leak in the header / silencer joint ??

  • Hamish

Posted July 15, 2004 - 10:34 AM


i doubt having the packing blown out would make a noticeable difference, but a leak in the header/muffler joint will definately do it. Also check the header to head join. When you remove the header pipe it's easy to see where it was leaking. just look for black blow marks

  • Brettv

Posted July 15, 2004 - 04:13 PM


thanks for the info guys, ill have a look.
cheers :thumbsup:

  • The_Missile

Posted July 18, 2004 - 11:47 PM


........... but a leak in the header/muffler joint will definately do it.

I'm curious, why would that be ? Whats going on that would lean it sufficiently to make it pop/backfire ? I know various pressure things are going on in the header / (silencer?) but am completely clueless.

  • N7SLC

Posted July 19, 2004 - 02:47 AM


The octopuss is a air cut-off valve. On deceleration, the valve is
actuated by vacuum which richens up the pilot circuit. If you remove
the octopuss, then the pilot circuit will be lean on decel causing
popping. You'll need to richen the pilot circuit some (in my case,
The biggest problem with the air cut-off valve is that over time, the
rubber diaphram gets worn or hardens up which causes it to not
function properly. In my case, it made low-speed jetting very


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