« previous next »
Pages: [1]   Go Down

Author Topic: Carb  (Read 731 times)

0 Members and 1 Guest are viewing this topic.

Offline patlac

  • Full Member
  • *
  • Posts: 15
Carb
« on: April 18, 2011, 03:44:30 PM »
 Hi My 77 400/4 is running rich and causing plugs to fail My colourtune shows a nice Blue so why are plugs black. Is it possible to lower the needle on Keihin carbs. I have adjusted air screw to no avail. Compression is 120 on all Cylinders/
Logged

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,802
Re: Carb
« Reply #1 on: April 18, 2011, 04:08:41 PM »
Is the stock air filter clean as new, less than one year old?

Are the white insulators black on the spark plugs?  How old are they?
Do all spark plug show the same deposit pattern?

The air screw adjusts the pilot mixture and is dominant in the idle to 1/4 throttle range.
The slide needles are adjustable by changing the clip position.  1/4 to 3/4 throttle position dominant.
The main jet dominates the mixture from 3/4 to full open throttle position.

Has the routine 3000 mile tune up check list been completed?

Cheers,
Logged
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 patlac

  • Full Member
  • *
  • Posts: 15
Re: Carb
« Reply #2 on: April 19, 2011, 02:48:32 AM »
The Plugs were new they are black all over on all 4 cyls.The air filter is a new standard one ,All relevant checks carried out. I rechecked Choke and it appears to operate ok.
Logged

Offline dave500

  • Really Old Timer ...
  • *******
  • Posts: 17,080
  • WHAT?no gravy?
Re: Carb
« Reply #3 on: April 20, 2011, 03:00:42 AM »
120 sounds low,did you have the throttle wide open during the test on a hot motor?
Logged

Offline 333

  • Time for change
  • Really Old Timer ...
  • *******
  • Posts: 7,558
  • Mail List Member #162 - Call me Stan
Re: Carb
« Reply #4 on: April 20, 2011, 06:29:56 AM »
How long do you run the choke when first starting up?  I've always been a fan of less then 10 seconds.  It takes a bit of throttle work to do that, but I never have to worry about fouling plugs.
Logged
Go metric, every inch of the way!

CB350F0  "Scrouching Tiger"
CT70K0    "Sneezing Poodle"

www.alexandriaseaport.org

Offline Bob Wessner

  • "Carbs Suck!"
  • Really Old Timer ...
  • *******
  • Posts: 10,079
Re: Carb
« Reply #5 on: April 20, 2011, 06:36:49 AM »
Sounds like my procedure (K0), though in the early, colder months, it might be more than 10 seconds. As soon as I can ease the choke lever down and keep it running with a bit of throttle, I do it. Actually, if I keep the choke on too long, it will begin to stumble anyway.
Logged
We'll all be someone else's PO some day.

Offline Skunk Stripe

  • Expert
  • ****
  • Posts: 817
Re: Carb
« Reply #6 on: April 20, 2011, 08:41:09 AM »
What do you mean by standard air filter? Is it a honda filter or a different paper filter? The cheap paper filters are too restrictive and will make things rich.
Logged

Offline patlac

  • Full Member
  • *
  • Posts: 15
Re: Carb
« Reply #7 on: April 21, 2011, 03:41:24 PM »
ok guys The air filter is the  genuine Honda Part,I only use the Choke to Start and push it off straight away I have new plugs in the bike and it appears ok. but it did before for about 50mls. I will soon have to put bike away as I am getting a Knee replacement in June.So I will Try to put up some miles before then. Thanks for all replies and Tips
Logged

Offline moham

  • .fnord.
  • Expert
  • ****
  • Posts: 1,108
Re: Carb
« Reply #8 on: April 21, 2011, 06:23:19 PM »
tech forum, maybe?

i mean, this thread isn't about babies or homemade bbq pits, so...
Logged
78 750K-The Ocho
74 550-The Cherry Picker
70 750K0 motor-Dick in a Box
Pages: [1]   Go Up
« previous next »