Author Topic: 1978 Honda CB550K not running on cylinders 1 and 2  (Read 549 times)

0 Members and 1 Guest are viewing this topic.

Offline cado007

  • Full Member
  • *
  • Posts: 37
1978 Honda CB550K not running on cylinders 1 and 2
« on: September 03, 2024, 05:44:16 AM »
1978 Honda CB550K not running on cylinders 1 and 2
I bought this bike a couple months ago and totally deracked carbs and cleaned. Kept all original brass.  Bike is stock- stock airbox -stock mufflers - stock jet sizes and needle location.  The compression initially was 100 on cylinders 1 and 2 and 125 on 3 and 4. This bike had been sitting for some time.  I had it running well and put about 400 miles on it. Usually in 80 mile round trip Sunday rides. Well I could never get it to idle under 1700 rpms. I checked my tach with digital tachometer and it was accurate.  It seemed like it eventually want to idle even higher or it would stall at lights. Hondaman suggested trimming Advance spring which I may still do, but I took off advance cleaned it - it looked great and springs seemed good. Anyway I decide to remove carbs again and clean slow jets again. Now after cleaning it will only run on cylinders 3 and 4. I also just put new coils wires caps and plugs on it. I have fuel in bowls 1 and 2. 2 has new plug and will spark outside engine. All have spark. I rode it down the street on 2 cylinders and pulled 2 plug. It still looked new and had a faint smell of gas. I rechecked compression now 80 psi on 1 still 100 on 2 - did not check 3 and 4 as they were running fine. So my question is - do I remove carbs again an clean again or could something inside be causing this issue. To recap it was running on all 4 cylinders before the carb rebuild and was pulling well through all gears. I had it up to 95 once. It also started right up with the choke on for just a few seconds. Maybe I should have just lived with the high idle. Any advice would be appreciated.

Offline robvangulik

  • Honda Fourever
  • Expert
  • ****
  • Posts: 1,417
Re: 1978 Honda CB550K not running on cylinders 1 and 2
« Reply #1 on: September 03, 2024, 07:16:53 AM »
You didn't by accident switch plug wires 1 and 2, did you?

Offline cado007

  • Full Member
  • *
  • Posts: 37
Re: 1978 Honda CB550K not running on cylinders 1 and 2
« Reply #2 on: September 03, 2024, 07:31:03 AM »
Hi Robvangulik,
Actually initially or at one point after installing new coils i did - but I switched them correctly and same problem persists.
Would that have caused an issue?
Thanks,
damon

Offline calj737

  • Really Old Timer ...
  • *******
  • Posts: 21,014
  • I refuse...
Re: 1978 Honda CB550K not running on cylinders 1 and 2
« Reply #3 on: September 03, 2024, 07:36:59 AM »
If you leave the choke ON, will it run on all 4 cylinders?
'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline cado007

  • Full Member
  • *
  • Posts: 37
Re: 1978 Honda CB550K not running on cylinders 1 and 2
« Reply #4 on: September 03, 2024, 07:39:19 AM »
Hi Calj737,
I thought I tried that and it did not work - but I will try again.