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Discussion Starter #1
l think I need smaller primary main jets in my CB360-it has stock air filers, stock 68 primary main jets and 100 secondary main jets, stock headers with aftermarket mufflers.

It runs super rich at small throttle openings, I have set the idle mixture lean and dropped the float level to 21 which has helped but it still runs like a pig at that 3500-5000rpm small throttle stiing you use in town. At half throttle and full throttle it runs great.

Anyway, looking around these jets seem to be the closest I can find:


They are slightly longer than the jets in my carb that are 7.2mm long.

Will they work?

Are the jet sizes the same as stock-ie will a 68 in this jet work the same as a 68 stock jet?

Any suggestions on sizes to get-will the two sizes down be enough?

Is it likely I will need to embiggen the secondary main jets?
 

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If the new jets you want to use differ AT ALLL from the originals, they will alter performance. Longer jet will sit deeper in the fuel which will alter mixture.

I doubt your problem is with the primary jet size though. Could be clogged filters, diaphragm problems, clogged emulsion tubes or passages, or carbs not synced. In my experience, 360’s are VERY sensitive to mixture screw settings, and syncing.
 

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Discussion Starter #3 (Edited)
Carbs are spotless clean, had two baths in the ultrasonic cleaner then carb cleaner sprayed through every orifice. Emulsion tubes are clean, all passages are clear, diaphragms are good, filters are good. Carbs are synched. I had the idle mixture just so (set with the vacuum guages) but I've set it lean now to help with the rich off idle problem.
Has anyone used the longer jets, I've seen them mentioned but no one says how they work.
Does it matter if they sit lower in the fuel, it will be at the same level inside the jet won't it?
Common Motor sell a jetting kit-are these jets OK?
 

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where the jet sits in the fuel determines lean/rich mixture. same as float level. longer jet = higher fuel level. only use Keihin jets unless you absolutely have to use aftermarket. you can get OEM part numbers from CMSNL. Jets r us still has some Keihin jets, and you can still find some on ebay, partzilla etc.

Check your advance unit as well. Loose springs and worn shims can cause uneven advance and over-advance.

Common motor stuff will not be OEM, but it will be expensive.

you can find more help over at the other twins forum. not hard to find with google. can't link to it because it gets censored.
 

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Multiple manuals for the CB/CL360 motor say the carburetor float height should be 18.5mm between the bottom of the float and the bottom of the carb body where the bowl gasket sits. You might want to recheck the float level and the angle of the carb while taking the measurement. You want the float to be touching the fuel inlet valve but not be compressing the spring, about 30 degrees past vertical.
float level Clymer 360.jpg
 

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Discussion Starter #6
Yeah I had the level at 18.5 but dropped it to 21 to try and lean out the mixture, and it did help so the bike is now rideable (barely).
I've ordered a bunch of jets but they are the 8.5mm long ones, couldn't get the 7.2mm ones so I'll see how they go.
 

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You say this spec is wrong, then do tell what is the correct float height, and where is it published?
All my printed sources give a float height of 18.mm in the Honda official Shop Manual CB250-CB360-CL360 (1976) on page 67, and the Clymer manual 250&360cc twins M323 (1983) on page 99. The carb data page on 4-stroke.net lists 18.5mm. Common Motors sells a float level gauge and the spec given on the product page is 16-17mm.
In any case, mikeyvet, find the settings that work best on your bike.
 

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The correct spec is not officially published anywhere, that’s the problem. Guys that have been around 360 carbs for years say 20-21mm. It works for my bikes and many others. Searching this forum, the other twins forum and do the ton will reveal much information. Info from Common motor and Clymer is sketchy at best.
 
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