SOHC.co.uk Forums > CB500/550
CB500 runs lean and doesn't want to pull through
Erny:
If I may contribute with my story:
Back in 2019, I was working on low RPM hesitation/too rich problem with my CB550K1 / 022A carbs (engine hesitating in lower RPMs and felt like too rich)
Finaly I fixed that:
1. I first replaced points and advancer by Boyer ignition (I kept stock coils). Result - engine hesitation at lower RPMs almost gone! This for me confirms Mark's advice with worn/annealed advancer springs as Boyer has built in advance/retard in ECU. Checked with strobo, it now works as it should. But back to this topic reported too LEAN by RBoss - I think that advancer spring issue is rather too rich "effect". I discussed that with Mark Paris too BTW ;)
2. Too rich problem was caused by corroded emulsification tubes (genuine Keihin) that had bigger ID holes due to corrosion. Replacement by new Keyster (OEM needleds kept) and later by new genuine OEM set (tube+needle) fixed that. Engine now runs smooth on idle and also very smooth from idle RPMs, it picks from ~1500-2000 RPM smoothly. Current issue is that it is too lean now ::) (only tubes and needles changed, jets are the same)
K2-K6:
--- Quote from: Erny on February 25, 2022, 10:06:34 PM ---If I may contribute with my story:
Back in 2019, I was working on low RPM hesitation/too rich problem with my CB550K1 / 022A carbs (engine hesitating in lower RPMs and felt like too rich)
Finaly I fixed that:
1. I first replaced points and advancer by Boyer ignition (I kept stock coils). Result - engine hesitation at lower RPMs almost gone! This for me confirms Mark's advice with worn/annealed advancer springs as Boyer has built in advance/retard in ECU. Checked with strobo, it now works as it should. But back to this topic reported too LEAN by RBoss - I think that advancer spring issue is rather too rich "effect". I discussed that with Mark Paris too BTW ;)
2. Too rich problem was caused by corroded emulsification tubes (genuine Keihin) that had bigger ID holes due to corrosion. Replacement by new Keyster (OEM needleds kept) and later by new genuine OEM set (tube+needle) fixed that. Engine now runs smooth on idle and also very smooth from idle RPMs, it picks from ~1500-2000 RPM smoothly. Current issue is that it is too lean now ::) (only tubes and needles changed, jets are the same)
--- End quote ---
It's an interesting input, but I feel that crosses over too many causes in this area. The problem of too rich mixture will ordinarily be assisted by a good electronic system especially compared to one that is not certainly performing well (it's one of few areas it may hold distinct advantage) and so mask the real problem of fuel metering.
The true fix is to correct the mixture as you're finding I believe.
Erny:
In fact, I first did ign replacement back in 2019. This fixed most (not all) of engine hestation in lower RPMs that I felt as if engine has too much advance/too rich mix. However, still rough/uneven behaviour stayed in idle to low RPMs (typically, cruising in the city, you want to open the trottle a bit from closed).
This is no totally gone by replacing corroded emul.tubes last year. Now just with bench sync (using steel balls from bearings) engine runs very smooth! before it was impossible to sync carbs properly, even with gauges
Once I fix current too lean mix I hope I'm done... But knowing myself I'll be hunting to reach at least 100mph topspeed ;D ::) 8)
corroded tubes topic here: http://www.sohc.co.uk/index.php/topic,25641.msg235103.html#msg235103
deltarider:
I have two TEC advancers and none of them give a problem. I never understood what could be gained by cutting the springs. When under 2500 rpm a somewhat fluttering idle and near idle annoys you, you can order a fresh set of springs. In normal riding practice, when I open the throttle, revs will be over 2500 rpm in a split second anyway, the advancer weights having reached the stops. What is there to gain then, that Honda overlooked? I can imagine however, that on snap closing the throttle, there may be a slight hesitive returning to a dead on steady idle, but I don't see that as much of a problem. On the contrary, it could make driveability less nervous. Let's await the results of Andreas Milke, who has made a programmable EI. When I look at the CB500/550 engine in standard form: four 125cc lawnmower engines put on a crank sharing a very tame camshaft for breathing, I don't expect much of it. But Andreas has ofcourse another reason for his experiment as the gas in Brazil contains a lot of alcool.
Bryanj:
Honda never supplied the springs seperate
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