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I had a misfiring problem that wouldnt go away and after cleaning the carbs and replacing the brass, I realised that the needles need to be changed as well as the replacements are subtly different. I went back to my original brass and needles and after all the cleaning and balancing it runs beautifully again.
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« Last post by Nurse Julie on April 16, 2024, 05:41:47 PM »
True, but it “might” be a good? 😌
Indeed, it may be good.
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« Last post by beardylondon on April 16, 2024, 05:38:03 PM »
True, but it “might” be a good? 😌
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« Last post by Nurse Julie on April 16, 2024, 05:35:51 PM »
From China
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« Last post by beardylondon on April 16, 2024, 05:25:18 PM »
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« Last post by deltarider on April 16, 2024, 04:24:56 PM »
All the original cables i saw in the 70's had a black lining on the inner cable [...] Thanks Bryan. The old original cable I have kept also has a black lining on the inner cable. The one on the bike for the last 60.000 km - also original - IIRC gray but as soon I have checked I'll report. [...]
I doubt that Honda will do anything as you do not know where it originally came from, that dealer is gone so cannot provide purchase details and finaly time in stock
So far Honda seems very interested. Seller has 30 more. He has bought them back in the day of a dealer that went out of business. The difference in quality is substantial. My old cable weighs a ton compared to the one in the package. Still the cable I bought of him may well be original. What puzzles me is that the partnumbers, including the 3 digits MODIFICATION DESIGNATION, are identical.
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« Last post by Bryanj on April 16, 2024, 01:56:49 PM »
All the original cables i saw in the 70's had a black lining on the inner cable and should have had a white inner coating on the outer but you only saw that if the outer was damaged.
I also know for a fact that the taiwanese manufacturers at the time would package anything in the way the buyer asked, i bought many Yamaha FS1E cylinders in packaging identical to original.
Honda cables normaly had the part number in white on the outer sleeve.
I doubt that Honda will do anything as you do not know where it originally came from, that dealer is gone so cannot provide purchase details and finaly time in stock
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« Last post by deltarider on April 16, 2024, 01:16:01 PM »
I have informed Customer Support of Honda EU on the matter and they are investigating it.
Note that the cable lacks the thicker part against chafing. The cable is much thinner than the previous 22870-323-621 ones I had and I could not detect the inner Teflonlike lining. When you zoom in on the pic, you will notice a detail: the little coupon wich mentions the partnumber has 'Japan' cut off from 'Made in Japan'.
My hope was that mechanics that have worked on these bikes, could remember/testify that inspite of the identical partnumber 22870-323-621 cables could nonetheless differ in quality. That would be exceptional however. The underlying systematic of Honda's partnumbers code is, that even when the smallest detail of a part is modified, the last three digit number in the partnumber will change.
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« Last post by Martin6 on April 16, 2024, 09:11:15 AM »
Yep, you described the way an air screw works.
I wrote to Mark directly, to double check what he had written and he confirmed:
"The idle-air screw in those carbs (all of the 750 roundtop carbs) controls the amount of fuel-air mixture that gets pulled up for each intake stroke. It is already mixed as fuel & air inside the tiny tube on the top of the idle jet, where those holes are, when air from the little brass orifice at the back of the carb's bell met the rising fuel in the jet's metering hole. Then, the position of the screw admits more (or less) of this mixture during the intake suction."
I am testing this now. I had 2 lean plugs and 2 sooty. The lean I opened up 1/8th turn. The sooty, in 1/8th. I have found two of my lean showing plugs are tan and one of my sooty plugs is improved. The other is still sooty, so I am trying a further 1/8th in.
All on non-ethanol fuel, but general riding, not a strict plug chop, as I believe my needles are in the right position, stock jets, airbox, 341 exhaust etc. Points set, timing checked, ditto valve clearances. Carbs are cleaned, synch'd and float levels triple checked. Although I do find float levels a little tricky.
So, not conclusive, but the early signs for me is following this advice has given me a small improvement.
I apologise if this has taken us away from@Pauarc's original problem. It could be relevant. Not difficult to just give it a try, after adjusting the floats to spec. 👍
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« Last post by K2-K6 on April 16, 2024, 12:26:38 AM »
Agree that it would be ideal to reset the float height to get equal volume, within reasonable scope, for all the carbs. Certainly it should remove suspicion at least for further evaluation.
I just can't see the view given by that scource about the direction of the airscrew in mixture volume though. Highly suspicious that's wrong and obviously contentious.
There's a good comparison too, with the F2 PD carbs, having the "mixture" adjustment screw on engine side of throttle slide, they emphatically work to change fuel volume rather than air. This type is turned out to increase fuel volume at low speed circuit.
These carb, K series, with screw on airbox side of throttle slide, change the air volume to alter mix by giving more air bypass to the circuit when moved outward (anticlockwise) such that the venturi vacuum can then exert less "pull" on the installed idle jet. Close them right inward, then it's pure fuel and no air they suck. Out makes it leaner, and sounds so too.
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