Author Topic: Jetting Question  (Read 1578 times)

0 Members and 1 Guest are viewing this topic.

Offline ACVWguy

  • Full Member
  • *
  • Posts: 62
Jetting Question
« on: September 14, 2011, 11:23:18 AM »
My cb550 is in perfect running condition and I have just recently done the full 3000 mile tune-up. But I have also recently installed a uni 4055 airbox foam filter and a 4-2 exhaust system with straight-through fiberglass baffles. My bike doesn't seem to want to open up in the higher revs (6-9000rpm) like it's supposed to. I know that it should have more power than it does so I figure that, since everything is adjusted and cleaned as needed, the only thing left to do is up my main jet size, as I am still running the stock size jets. I did a full throttle plug chop and found that my plugs were white, so my bikes running lean.

I need to upjet to get this bike running right. So with my intake and exhaust, what jet size should I start with? 105s or 110s? I just don't want to waste my money on an uneducated guess at jets (though I do understand that jetting is a trial and error thing).

Here's a pic of my exhaust for better reference:

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,805
Re: Jetting Question
« Reply #1 on: September 14, 2011, 11:30:02 AM »
What position is the slide needle clip in?
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline ACVWguy

  • Full Member
  • *
  • Posts: 62
Re: Jetting Question
« Reply #2 on: September 14, 2011, 11:43:02 AM »
The  e-clip is in the second notch from the top of the needle

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,805
Re: Jetting Question
« Reply #3 on: September 14, 2011, 12:53:36 PM »
The  e-clip is in the second notch from the top of the needle

Move it to the 4th notch from the top  (which is the stock setting, btw).  Drive for effect.

You do have #100 for the main, right?
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline ACVWguy

  • Full Member
  • *
  • Posts: 62
Re: Jetting Question
« Reply #4 on: September 14, 2011, 04:16:44 PM »
Ok, I just went out and pulled the caps off my carbs... turns out the e-clip is in the 2nd from the bottom groove on the needle (4th groove). Sorry for the confusion.  :-[

And yes I do have 100 mains

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,805
Re: Jetting Question
« Reply #5 on: September 14, 2011, 04:33:18 PM »
Ok.
Do you know what the fuel level is in the bowls?  S/b about 2-4 mm from the bowl interface.

Did you verify that the spark plug deposits on all four are the same?
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline grasscutter

  • Enthusiast
  • **
  • Posts: 243
  • Love the CB650.
Re: Jetting Question
« Reply #6 on: September 15, 2011, 08:37:22 PM »
Its been my experience to not move the needle e-clip until you are done jetting and then just doing final fine tuning. 

Up the mains.  Soon!  Not good running lean.  Especially if you're out on the bike @ WOT.   
Come on!  We're burning daylight!

Offline ACVWguy

  • Full Member
  • *
  • Posts: 62
Re: Jetting Question
« Reply #7 on: September 17, 2011, 10:23:34 PM »
I set the floats to stock settings when I rebuilt the carbs... 22mm IIRC... And yes all of the plugs are white at a WOT plug chop. After a few minutes of idling, the plugs become more tan.

Offline Danno

  • Hot Shot
  • ***
  • Posts: 715
  • 74 CB550,75 GL1000,76 KZ400,77 GL1000,73 CB750
Re: Jetting Question
« Reply #8 on: September 17, 2011, 10:35:27 PM »
for that rig you will probably need 40 slow jets and 110 mains or 105 if it not as loose as I am thinking but do not move the needle clip yet and if you do you move the clip down one notch which moves the needle up not the other way around if you move the clip up it moves the needle down and therefore decreases the rate fuel is mixed with air the rig you describe is the same rig  I am running white plugs mean lean
when you own a motorcycle the wife does not have to find you handy she just has to find you