Topic: CB550 Four K3 1979

[Cruiser]

Did another ride yesterday, she purred along nicely, however still rich according to the plugs. Not sure what else I can change at this stage except for going for a different, non stock, main jet size.

Still have a few concerns though. That high idle on a cold startup... Goes immediately to 3000 or 3500 RPM, so I immediately have to grab the idle adjustment screw on the carb to bring her down. After 20seconds or so, the rev's go down and I can readjust the idle screw. Once the engine is warm, this no longer happens, I can just start it and it instantly idle's normally.

Second thing I've got: Is it normal that when I turn the ignition on, I sometimes get spark and when there is still some fuel in the piston/exhaust the loudest bang (igniting fuel) ever. Scared the life out of me for a couple of times.

[bryanj]

The K3 has a fast idle cam on the choke mechanism as the carbs run so lean so that is normal, the spark is not, unless you have fitted electronic ignition

[Deltarider]

[...] Still have a few concerns though. That high idle on a cold startup... Goes immediately to 3000 or 3500 RPM, so I immediately have to grab the idle adjustment screw on the carb to bring her down. After 20seconds or so, the rev's go down and I can readjust the idle screw. Once the engine is warm, this no longer happens, I can just start it and it instantly idle's normally.

Very common for K3s. Previous models with the oldstyle carbs had the opposite.

Second thing I've got: Is it normal that when I turn the ignition on, I sometimes get spark and when there is still some fuel in the piston/exhaust the loudest bang (igniting fuel) ever. Scared the life out of me for a couple of times.

Not normal. What ignition do you have?

[Cruiser]

Electronic ignition... Anything I can do to fix that?

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[Cruiser]

The K3 has a fast idle cam on the choke mechanism as the carbs run so lean so that is normal, the spark is not, unless you have fitted electronic ignition

But it does this regardless I use choke or not? Not sure, but even thought it was less if I started with the choke out. Hard to know however since I need to hold my choke to keep it open. When I release it, it immediately springs back to its closed position.

[bryanj]

There is a friction nut on the choke cable outer to keep it out as to the exhaust only cure is refit points

[Cruiser]

There is a friction nut on the choke cable outer to keep it out as to the exhaust only cure is refit points

That was well hidden underneath the rubber grommet! Thx, another issue fixed.

Still some little aesthetic things left, need to redo the seat (they covered the original one with a bad looking seat and rivits), need to find that grab bumper bar that runs from one shock to the other (behind the seat), get some original mirrors.

But in the meantime, I'll enjoy it a bit more

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[bryanj]

Grab bar not easy, try ebay us, original mirrors way too expensive, many others look just as good

[Cruiser]

Grab bar not easy, try ebay us, original mirrors way too expensive, many others look just as good

Well for the mirrors, I find they are 36 eur's for one. That doesn't sound too bad.

I do wonder why they ditched the grab bar though. For me it looks so much better with it.

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[Deltarider]

Grab bar not easy, try ebay us, original mirrors way too expensive, many others look just as good

Well for the mirrors, I find they are 36 eur's for one. That doesn't sound too bad.

I do wonder why they ditched the grab bar though. For me it looks so much better with it.

I agree. I specially ordered one for my model, a repro, made in Italy which is even better quality than the original.

[Deltarider]

For less than € 100,-: https://honda4parts.nl/product_info.php?products_id=1912
A new one from CMSNL is over € 200,-

[Cruiser]

For less than € 100,-: https://honda4parts.nl/product_info.php?products_id=1912
A new one from CMSNL is over € 200,-

Saw that one as well, but it says no longer in stock. So its sold already sadly

[Deltarider]

Did you contact them? Maybe 'niet langer meer leverbaar' applies to new ones. Maybe.

[Cruiser]

Did you contact them? Maybe 'niet langer meer leverbaar' applies to new ones. Maybe.

Well the website says: Availability: No longer available. But I've sent them a mail anyway (thx for the tip! ).
Edit: they just confirmed, no longer available sadly.

I've asked "Blauwe Plaat motoren" as well if they have one laying around. But I doubt with the fire they recently had, that they will have time to check.

Would love to visit that workshop though one of these days. And its not that far from my home either.

[Deltarider]

They had a fire? Really?! Anyway, I'll be on the lookout for you.

[Cruiser]

They had a fire? Really?! Anyway, I'll be on the lookout for you.

Wait, what is this cryptic writing? Now I need more info!

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[Deltarider]

Means, when I visit friends next Friday and a specialist next week I'll ask if they have an used one lying around. The friends possibly not: they're specialized in the old models, Fourdeel Purmerend maybe, but he is on a vacation right now.

[Cruiser]

Means, when I visit friends next Friday and a specialist next week I'll ask if they have an used one lying around. The friends possibly not: they're specialized in the old models, Fourdeel Purmerend maybe, but he is on a vacation right now.

Great! I appreciate that!

[Cruiser]

Since she's still a bit rich I was wondering if installing the old (OEM keihin) needles would be a big difference compared to the needles from the rebuild kit I used (Keyster).

I also notice on the old needles that they had the clip on the 2nd (and thus leaner) position compared to the stock 3rd position (what I've also put the new ones on).

Could it be that the Keihin's are better compared to the Keysters? Or shouldn't that make a big difference?

The old ones still look good (sharp pin as well).

Worth a try to put the old ones in with the clip in pos 2? Or should I also pop in the Keihin main jet then? That could use and ultrasonic clean.

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[Deltarider]

Others may comment on your carbs. Since your bike stills run rich, I would like to know what airfilter you have.

[Cruiser]

Others may comment on your carbs. Since your bike stills run rich, I would like to know what airfilter you have.

I've put this one in: https://www.cb-four.com/cgi-bin/shop/__Air-Filter-insert-Honda-CB550K3-CB500K3-new__2000045-02v_04.08.html

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[Deltarider]

OK. Can you check what condition it is in now? Look in particular for paper area that has become deformed and/or wet or shows soft, sometimes brown spots. I'm asking because I have seen a few which had lost part of their 'breathing' capacity due to contamination caused by fumes/vapour coming out of the breather filter underneath it, which is supposed to separate oil and vapour from the crankcase gasses.
What I would do, is do a test ride with the airfilter element removed and see if it still runs rich. For this I would temporarily disconnect the breather tube from the airfilter case.

[Deltarider]

Also I'd like to know the looks of the exit of your filter engine side. See pics.

[RAFster122s]

Your Keyster needles and brass parts likely are causing much of your running issues...

[Cruiser]

Also I'd like to know the looks of the exit of your filter engine side. See pics.

See pictures attached. Still looks quite good I'd say. Only driven 500km's with it.

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