Author Topic: CB550 Carb Rebuild Kit Question - Slow Jet & Screw Jet Same Size?  (Read 571 times)

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Offline campbmic

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Hey all! Im rebuilding a set of carbs on my 1975 CB550. I like the pentagon shaped gaskets instead of the round ones so I purchased this kit:
https://www.amazon.com/dp/B0D91X2VQ5?psc=1&ref=ppx_pop_dt_b_product_details

Floats, float valve, main jet, and needle set all seem good.

However, when I received the kit I noticed:

1. The float needle was a little taller than mine, not a big deal as the old ones were still in decent shape.

2. What I call the "screw jet" (the jet that screws into the outside of the carb) the hole was a little smaller and a bit further down the pointy end of the jet. Not sure if that would be an issue.

3. What I call the "slow jet" the thin long jet that screws in next to the main jet, was a lot shorter, but the holes seem to be in the same place. This new jet is as long as the new "idle jet".

I assumed I received the wrong kit, but after looking I saw A LOT of the kits I see online have the same jets as the one I received. Are these some new version of jets that replace original ones? Or did I in fact get the wrong kit?

Im pretty sure its the wrong kit but just wanted to check before returning. Anyone know what this kit is for? Thanks!
« Last Edit: May 14, 2025, 11:36:05 PM by campbmic »
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Offline M 750K6

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Re: CB550 Carb Rebuild Kit Question - Slow Jet & Screw Jet Same Size?
« Reply #1 on: May 15, 2025, 12:17:30 AM »
I had bad experiences with Keyster branded brass on a 750. TBH, at $33 for all 4 carbs, I very much doubt you have precision engineered brass in that kit.

Offline Mark1976

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Re: CB550 Carb Rebuild Kit Question - Slow Jet & Screw Jet Same Size?
« Reply #2 on: May 15, 2025, 05:58:45 AM »
   Well lesson #1, never (ever) buy cheap aftermarket carb kits. Clean up the original brass (mains, pilots, emulsion tubes and the slow mixture screws) and see what they look like after cleaning, if your fortunate you'll only need to replace the o-rings for the mains and the seat and bowls. Bowl o-rings, round or preformed, it doesn't matter, just like the other o-rings, its about correct size..
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Offline campbmic

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Re: CB550 Carb Rebuild Kit Question - Slow Jet & Screw Jet Same Size?
« Reply #3 on: May 15, 2025, 04:17:50 PM »
   Well lesson #1, never (ever) buy cheap aftermarket carb kits. Clean up the original brass (mains, pilots, emulsion tubes and the slow mixture screws) and see what they look like after cleaning, if your fortunate you'll only need to replace the o-rings for the mains and the seat and bowls. Bowl o-rings, round or preformed, it doesn't matter, just like the other o-rings, its about correct size..

Meh, I've rebuilt the carbs twice and used cheap kits and both those times it worked out great. Its just very weird to me there are SOOO many of these kits being advertised for '74-'76 CB550s. I was wondering if the kits work on some of them.

1. https://www.ebay.com/itm/403905287876?_skw=cb550+carb+rebuild&itmmeta=01JVB3DSFTWY9T2BRFWARW5WN4&hash=item5e0aa196c4:g:ssUAAOSwywpkinl0&itmprp=enc%3AAQAKAAAA0FkggFvd1GGDu0w3yXCmi1cV367xCxSuHULlELBJPbRDglvH5siGyJIMCD64jJCNzneVDB%2FYZp3YUm%2Bm561oTA0dLH%2BP%2BebbHuhwwCDbJ%2Fq36rtDU6dBTKA6zkkGLHheDt1e272RP3ym9yy8kY9fMg2Jpp8kR5Grnvd%2Fm1p8qT5NVibdteqlLtpLhCiK%2FUWOBiLDtbwNbM98DvWZitGB8LVhOa0a2B61XCmAEJ1rw1DPDRC7qPgTmRvEmdmgwRSHFxP0JQT4wbc81u3PsW2c378%3D%7Ctkp%3ABk9SR5CYt-PaZQ

2. https://www.ebay.com/itm/254223025292?_skw=1975+cb550+car+rebuild&itmmeta=01JVB3N3TXFZ6WNMCJK3XVDHCV&hash=item3b30df848c:g:EQgAAOSwXlZiHbch&itmprp=enc%3AAQAKAAAA8FkggFvd1GGDu0w3yXCmi1dV6wLSKoJKXSACD5veCKSw5n15H5znngGmq90jVmtVaY9J%2F8NiG5XE6qiMj7LrLCI1x444yNw%2F96c0PWFw5Jevxiu46M4PdujTpjqKsZZXeOPCK8pklsBOz9Ks1FpsicjuIURUp40QNCV2kv%2FQ8UBz%2FxAvz9q1OT0X3vYAF5Sbnb1FI8iFmQAZXZebOY0RSaTkttgCmarbBFYnY9%2BFDyAjLgoHIOdo%2FKkvzZ2TFhNLJXTQo66JLCzgHh9euoMzQAegUHrTQR8JXKVBC9b3nY8AtUWFizddlkglC3dBA3Lp9Q%3D%3D%7Ctkp%3ABk9SR9C91OPaZQ

3. https://www.ebay.com/itm/184648546895?_skw=1975+cb550+car+rebuild&itmmeta=01JVB3N3TXV9SSKSVVGN933RBB&hash=item2afde93a4f:g:aqEAAOSwYE9mJ1mn&itmprp=enc%3AAQAKAAAA8FkggFvd1GGDu0w3yXCmi1dujlQVeuP3pHhVYhkb%2FqaHQfr4IWMrZWLHdUVZj2M1l%2F4W6bmFjEW825lxxf0FFHpMMBMuaAN57zOR6pXEgAwHXxSxYQbHpXwlb5718K5e00h1s8Sw5RL0xL76wA9cqQUuO%2B9fT8TVAPSZRLBWdHqEVcYrA7Y0EJmjq6kSgRl0VZBq93yHNmcTQjBawNVACoq2RrTvs6rT%2FhEZapZS65cx5hlHfHMmBxt1v5XcirAhVPXlfE7k4u6YuOUu1Yr8S6hm%2BH0Yi91F9DuV2pXgGb30e4yF8LtEvh6oF6yuxWdvrg%3D%3D%7Ctkp%3ABk9SR9C91OPaZQ

4. https://www.amazon.com/Carburetor-Rebuild-Repair-CB550F-1974-1976/dp/B0CZ6ZMF3G/?_encoding=UTF8&pd_rd_w=0r7hq&content-id=amzn1.sym.255b3518-6e7f-495c-8611-30a58648072e%3Aamzn1.symc.a68f4ca3-28dc-4388-a2cf-24672c480d8f&pf_rd_p=255b3518-6e7f-495c-8611-30a58648072e&pf_rd_r=9YEZF44X03H0CQRRVBD7&pd_rd_wg=uU50v&pd_rd_r=339ed950-207f-47cc-a71f-365c313c9c13&ref_=pd_hp_d_atf_ci_mcx_mr_ca_hp_atf_d

5. https://www.amazon.com/Vehicle-Carburetor-Rebuild-1974-1976-Replacement/dp/B0CQ4N91RZ/ref=sr_1_13?crid=3RJA092I0TC0D&dib=eyJ2IjoiMSJ9.Pkpb5_7un5Y_BTVdQTpEe5tMQ3QMW1vMFHyvUlXXTo1uct_YUD21QW7d3ZiQcQLP8fgpEQO9aCEayq_fRB44fI60n54ifSTrZL1lA-UUSRdx9blXhBtFkGWUNQ7Yu6MKC80eCh_xdTVQLIbfkIU8S8Xn7eBGnWqg3qkTjwOa9zO9BI_KZlPnP5uEpVmJGdTcg9yB-HLnFOU-dIHGPtbG6uKq8QJBTs2KSwEHGfDHlAZJpIE6NCRHvGAcdMwmxJJmxkqg3TAJIvDUmlQczCUezzdY4cflTJ-UoykpsV9Le88.wLM6cEncRf8UjZLNcy3ZJYeUrJzEmiXyzRIa-fE5T5I&dib_tag=se&keywords=cb550+carb+rebuild&qid=1747351037&s=automotive&sprefix=cb550+carb+rebuild%2Cautomotive%2C140&sr=1-13
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Offline CycleRanger

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Re: CB550 Carb Rebuild Kit Question - Slow Jet & Screw Jet Same Size?
« Reply #4 on: May 15, 2025, 07:15:04 PM »
Imho, Keyster makes the best aftermarket kit but the brass is not completely correct even in those kits.
You can still get some genuine Keihin brass from jetsrus.
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Offline HondaMan

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Re: CB550 Carb Rebuild Kit Question - Slow Jet & Screw Jet Same Size?
« Reply #5 on: May 15, 2025, 07:37:27 PM »
It's rare for the brass parts to wear at all, excepting the float valve body, in the 550 carbs. In fact, I have never seen worn-out brass that I would replace except for some water-damaged mainjets (sat for decades in water-wetted carb bowls).

The idle jets in your aftermarket kit won't work very well, if at all, in your 022 series carbs: they are too short. This causes incorrect fuel flow and idle troubles: I have replaced those jets before. I suspect they are for a different carb altogether?

The fuel valve may work if the tab on the floats does not have to be bent at a steep angle to reach the correct float levels. The 'valve closed' position should have the float's tab horizontal across the tip of the valve. If it is on an angle then the fuel level will be somewhat erratic, similar to when plastic floats are used in the early CB750 carb bodies that originally came with brass floats: then the tab has to be re-angled to make it more horizontal relative to the valve's tip. Yours may be similar.
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