Carb settings for a 4 into 1 exhaust.

[simonster]

I'm just rebuilding the carbs on my 72 500k1 which I think at some point in the past has been raced due to additional crudely welded rear set hangers. I bought it in a sorry state and I'm hopefully on the home stretch on a full nut and bolt cafe look rebuild which I started properly in February and has taken up many pleasurable hours since. I currently have the carbs split and would like to put them back to standard if possible, although I'm not sure if they will need jetting to suit the exhaust. All the carbs have the following fitted:
Needle 273004 with clip second notch from the top.
Main jet 100
Slow jet 40
Float valve 1.8
My aim is to gain motoring utopia, that is to say good power with optimum mpg..!! Pics will follow on this build from start to finish when i get the carbs fitted. These and the clocks to finish the build so nearly there. Cheers for any advice.


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[simonster]

My research shows that the main jet and slow jet are standard, just can't find anything about the needle or the difference with mine and 272304 which is also used on the 500k?


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[florence]

I think mine has 110 main which was grim with motad but once I changed to the laser pipe it started to run with more gusto.

needle adjustment will just depend on plug colour, set it how you think best.

[simonster]

I think I will stick to the jets and settings as they are and see how she runs. Cheers Florence


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[motad_uk]

am I being slow here?- what exhaust are you running?  certainly if its a road legal it should run fine on standard jets

you should only need to run larger jets on a "not for road use" system or any of the noisy horrors pretending to be road legal!

[simonster]

To be honest I'm not sure what make the pipes is. The I bought the bike as an engine in a frame with wheels and all the other components came in a box and that included the exhaust. It has been shortened I would estimate by 4-5 inch. I couldn't see any markings to identify the make or even be sure it has been run on the bike and the pipes have now been fully wrapped, premature I know! The bike looks like it has been raced in the past so I had assumed the carb settings would have been altered to suit that purpose. However, the jets are standard but not sure abt the needle. I have attached a pic in case anyone recognises the make of the pipes, long shot i guess.


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[motad_uk]

early Harris?

just about all of this style of pipe tend to have a hole mid range with perhaps some more at the top- just down to lack of volume and pipe lengths paying more attention to style than performance

a standard full throttle plug check  (flat out hit the kill switch and coast to a stop ) will at least check that the mains are not lean enough to damage anything  (unlikely)

you may just have to live with mid range- especially if you are not planning an air box- just describe it as "character"!

[simonster]

Cheers Motad, that advice does help and reassures me to stick with these settings and only alter things if problems are evident.


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