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Discussion Starter #1
Hi,
I've just built a 1999 CB750 nigthawk cafe racer and since removing the air box and changing the exhaust it runs a little rough to say the least, I was expecting to be able to get it set up on the dyno and a re-jetting and adjustment would solve the issue but the i'm told these carbs can't be used without and air box , Is there another carb set up from another bike I could use or maybe an aftermarket throttle body set up available ? thanks for any information.
 

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If I wanted to run pod filters directly connected to the carbs and have no box or plenum or velocity stacks,
I would go down to my local scrap yard and find anything other then CV carbs of the same size.
Without even looking at the numbers my guess is they would be coming off a SOHC 750 Honda or something similar displacement inline 4.

... how bad is it running now? does the power band just fall flat on its face?
 

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Discussion Starter #3
It runs but I haven't actually ridden it, as soon as it was built I sent it in for setting up , after seeing many people fit cone filters or bell mouths to their bikes in the 70's and 80's I foolishly thought it was just a case of re-jetting not realising these carbs were not suitable. I think the carbs from another maybe earlier Honda SOHC would be the sensible option, something that can be re-jetted, I just don't know what that would be ?
 

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Here's the thing, the carbs on your bike now, CV type are the epitome of carburetor complexity, they put those on to make the bike run as lean and fuel efficient as possible. Plus they are vacuum controlled, which from a pure performance aspect is not great.
Your motor is not all that different then the previous models save the fact you have 2 cams instead of 1 cam and rocker arms.

Pretty sure that riders of the old SOHC bikes that had regular old pre emissions concerns and leaded fuel days venturi carburetors, are not complaining about problems with pod filters and loud pipes.
... that is what you want right? loud pipes, pod filter, big open triangle, stock foot peg, no fender, no chain guard, powder coat LED everything, digital, firestone tires?
If not and you are building a race bike, then I would probably go with crazy expensive carburetors, likely worth more then your bike :|
 

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Discussion Starter #5
Thanks for the info, I have decided that due to the nanny state in Australia not allowing modifications without jumping through hoops I am getting rid of it and sticking to classic cars in future, too much like hard work !! Shame as it's almost there 20190818_132739.jpg
 
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