Author Topic: 550K1 - carb questions (022A)  (Read 1556 times)

Offline paulbaker1954

  • SOHC Pro
  • Posts: 579
  • I'll just be 5 minutes dear!!
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #15 on: June 24, 2019, 11:30:22 AM »
OK, now it is clear.
So I still have some issue to fix  :'(

One thing worth adding is that in fact the original Honda manual states that you should warm the engine up before riding. See below from manual

After the engine has been warmed up, the motorcycle is ready for riding.
If you think there's light at the end of the tunnel it's usually another train !!

2016 Yamaha MT09 Tracer
1971 Honda CB500 Four K0

Online Erny

  • CB750K7 CB550K1
  • SOHC Member
  • Posts: 237
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #16 on: June 24, 2019, 11:36:04 AM »
This is obvious  ;D
My only pb is cold start on choke and idling till engine is warmed-up
CB750K7 US model (1977)
CB550K1 US model (1975)

Offline deltarider

  • SOHC Pro
  • Posts: 575
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #17 on: June 24, 2019, 01:44:38 PM »
Fuelline to the T-joint of carbs 1+2 on your model (CB550K1) should have a length of 17 cm with an ideal internal ⌀ of 5,5 mm. The line to 3+4 should measure 28cm. However, if you happen to have the old model fuelcock (with the bowl), fuel lines lengths are 18 and 30 cm respectively. Outside ⌀ will be around 10 mm. With the correct dimensions there's no chance of kinking. Abstain from inline fuel filters. They'll cause irregularities on a CB500/550. The CB500/550 is very sensitive to correct fuel line routing.
« Last Edit: June 24, 2019, 01:52:46 PM by deltarider »

Offline deltarider

  • SOHC Pro
  • Posts: 575
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #18 on: June 24, 2019, 02:02:45 PM »
As for the chokes: the CB500/550 models with chokelever at the side of the carbrack were not ment to ride with the chokes (partially) on. There's a good reason for that: having the lever not in your view, you'll forget you have them partially on. Just keep your hand on the throttle. This practice is confirmed by the Owner's Manual. I guess Honda didn't want you to unnecessarily fiddle with a lever somewhere below that you can't see. Honda wanted you to have the hands at the handlebars at all times. No need to use the big idle knob unless you plan to do things with your right hand (which I often do btw). These models do not necessarily need a stationary warm-up as they had a pretty rich idle, so just a bit of throttle as the manual suggests. With the arrival of models with the chokeknob at the handlebars, it's a different story. They had a far leaner idle and a fast cam. For convenience the knob is now positioned directly in your view, so you can see whether it is engaged or not. Ofcourse you can choose what you like best. But if you need the chokes partially on whilst riding an old model, your idle is probably set too lean. 

Online Erny

  • CB750K7 CB550K1
  • SOHC Member
  • Posts: 237
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #19 on: June 24, 2019, 11:14:37 PM »
Small update, I'm just back from garage.

I did start the bike ususal way (w/o choke), after warm-up I was checking ingition, found stripped screw on 1-4 points  >:(, after fixing it, static settings and settings with strobe light I went for test ride. Bike generally pulls good, was able to rech pretty 90mph (reading on tacho gauge).
Mix screw set to 1 3/4 turns out (looked to me the best) on all, did not manage to make my RPM meter meauring reliably so did not played with each carb separately.

Another observation linked to carbs - after engine fully warmed-up, when idling stable for several seconds, I tried to quickly twist the trottle and engine dies! Is that normal? I manage to reproduce anytime... slower twisting is OK...

Note: after spending quite some time with points ( >:( >:( >:() where one is obviously replica, and still having strobe flashing irregularly, fire mark moving left-right, I'm strongly thinking about Dyna S. I installed it to my friend recently and it was really perfect...uncomparable with points. New points set cost ~100 USD, new Dyna S about 160..
CB750K7 US model (1977)
CB550K1 US model (1975)

Offline paulbaker1954

  • SOHC Pro
  • Posts: 579
  • I'll just be 5 minutes dear!!
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #20 on: June 25, 2019, 08:53:18 AM »
Small update, I'm just back from garage.

I did start the bike ususal way (w/o choke), after warm-up I was checking ingition, found stripped screw on 1-4 points  >:(, after fixing it, static settings and settings with strobe light I went for test ride. Bike generally pulls good, was able to rech pretty 90mph (reading on tacho gauge).
Mix screw set to 1 3/4 turns out (looked to me the best) on all, did not manage to make my RPM meter meauring reliably so did not played with each carb separately.

Another observation linked to carbs - after engine fully warmed-up, when idling stable for several seconds, I tried to quickly twist the trottle and engine dies! Is that normal? I manage to reproduce anytime... slower twisting is OK...

Note: after spending quite some time with points ( >:( >:( >:() where one is obviously replica, and still having strobe flashing irregularly, fire mark moving left-right, I'm strongly thinking about Dyna S. I installed it to my friend recently and it was really perfect...uncomparable with points. New points set cost ~100 USD, new Dyna S about 160..

I don't have any experience with Dyna ignition but I put the full Boyer kit on mine including the Micro Coils and I would highly recommend this set up. Bike just runs better all round, starts easier  and no more points maintenance !!

 Also very easy to fit and their tech support is excellent.

http://www.boyerbransden.com/microdigitalmicropower.html

You need KIT00289 and when I bought was £218

ALso see my post on how I installed the Boyer coils using the standard Honda brackets (makes for a very neat installation)

http://www.sohc.co.uk/index.php/topic,14509.msg117905.html#msg117905
If you think there's light at the end of the tunnel it's usually another train !!

2016 Yamaha MT09 Tracer
1971 Honda CB500 Four K0

Online Erny

  • CB750K7 CB550K1
  • SOHC Member
  • Posts: 237
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #21 on: June 25, 2019, 10:16:04 AM »
This is interesting, never heard about this ingition system!

Just wonder what is its reliability, because, still you can easily fix issues in legacy ignition. Of course, Dyna S brings electronics too (in fact replacing whole points plate and cam, but keeping advancer) but coils are still legacy.

I'll contact Boyer for some details ;)
CB750K7 US model (1977)
CB550K1 US model (1975)

Offline Oddjob

  • SOHC Jedi
  • Posts: 3048
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #22 on: June 25, 2019, 11:58:57 AM »
Where is SK? just trying to see what your location is.

Don't play stupid with me, I'm better at it

Online Erny

  • CB750K7 CB550K1
  • SOHC Member
  • Posts: 237
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #23 on: June 25, 2019, 12:16:50 PM »
SK = Slovakia (Slovak Republic), Bratislava, Europe  8)
CB750K7 US model (1977)
CB550K1 US model (1975)

Offline paulbaker1954

  • SOHC Pro
  • Posts: 579
  • I'll just be 5 minutes dear!!
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #24 on: June 25, 2019, 12:43:21 PM »
Where is SK? just trying to see what your location is.

Ha Ha not near Stockport then Ken :)
If you think there's light at the end of the tunnel it's usually another train !!

2016 Yamaha MT09 Tracer
1971 Honda CB500 Four K0

Offline Oddjob

  • SOHC Jedi
  • Posts: 3048
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #25 on: June 25, 2019, 05:18:28 PM »
Where is SK? just trying to see what your location is.

Ha Ha not near Stockport then Ken :)

It did cross my mind Paul, thought I could pop over and sort the carbs out for him.
Don't play stupid with me, I'm better at it

Online Erny

  • CB750K7 CB550K1
  • SOHC Member
  • Posts: 237
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #26 on: June 25, 2019, 06:07:25 PM »
You would be welcome to come! Anytime!
CB750K7 US model (1977)
CB550K1 US model (1975)

Offline paulbaker1954

  • SOHC Pro
  • Posts: 579
  • I'll just be 5 minutes dear!!
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #27 on: June 25, 2019, 10:50:26 PM »
Where is SK? just trying to see what your location is.

Ha Ha not near Stockport then Ken :)

It did cross my mind Paul, thought I could pop over and sort the carbs out for him.

Hey nice run to Bratislava
If you think there's light at the end of the tunnel it's usually another train !!

2016 Yamaha MT09 Tracer
1971 Honda CB500 Four K0

Online Erny

  • CB750K7 CB550K1
  • SOHC Member
  • Posts: 237
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #28 on: June 27, 2019, 09:31:31 AM »
Small update after yesterday carb sync (only #2 was out of sync):
- it now idles very nice when warm (sync definitely helped)
- start is OK somehow - after discussion here I consider it this way as OK and normal :)

However - under 3k RPM, using little trottle (typical when moving within city traffic), is NOT good.. Over ~3k it improves but still not perfect smooth and over 5-6K is really good.
When I try to use choke partially (under 3k RPM) it is significantly worse.
=> I have feeling that it is caused by too rich mix on low rpms.

One additional observation, when idling for few seconds and I'm twisting trottle quickly (I do not release immediately), engine kills. Is that normal?

Note:
What else I can try? I believe that playing with needles does not help as issue is on low rpm or I'm wrong?

CB750K7 US model (1977)
CB550K1 US model (1975)

Offline K2-K6

  • SOHC Jedi
  • Posts: 2644
    • View Profile
Re: 550K1 - carb questions (022A)
« Reply #29 on: June 27, 2019, 05:49:35 PM »
It looks to me that all of your assessment of mixture is telling you it's generally too rich, going with that feeling you'd need to experiment in the opposite direction to prove it or not.

If the needles are not in the middle clip groove then it seems logical to try them there.  As you note,  it doesn't directly affect mixture right at the bottom but it does attach it's graduation on top of the idle circuits. They have to at least be close at that changeover point to give a smooth response.

Flat spots are either mixture too rich to get it igniting cleanly,  or too lean to get the burn to start and complete entirely.  That ratio of air to fuel goes roughly from 10 to 1 (rich) and 14 to 1 (lean) at which points you'll feel it's not responding to the throttle.
These engines will generally run an average of around 12 to 1 approximately,  so if you have lean idle then rich mid range,  it will give very confusing responses.

What you are trying to do is step gently toward bringing the two parts of range together to give better average.

With needles in central setting and air screws closed a little you can assess it to see if that's the correct direction. Then further adjust the air screws from there.

What do you currently have the air screws set at?