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77 CB750 - Jetting question

Rayhalks

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Hi All, I'm new to this forum. I have worked on Harley and Triumph motorcycles for over 20 years now. Honda, not so much... But I'm enjoying working on my buddies CB750 for him. I just sync'd the carbs for him. The throttle response is bad, it bogs down. So I tested the lean theory with the choke. If I choke and 'rap' on the throttle, it's perfect. I also checked the plugs and they are very white and ashy looking, again, lean condition. The point gap is slightly on the 'tight' side, .012. I'm taking care of that, but the screws are stripped. I pulled the bowl on a carb and the main jet is at 124 (high end) and the pilot jet is at 35, I read 40 is stock. There are no mods to this bike, it is stock. My question is I know I want to take the pilot jet up some, but for these bikes, how much? Back to 40? To clear the 'bog' down while getting on the throttle, the choke is nearly fully engaged. Also, should I leave the main there at 124, or bring it down some? Thanks in advance...
 
I would up the pilot to at least 40. You will have to do the choke testing while riding it to see if the main jet needs to change. No needle clips on these carbs, you will have to use washer shims on the needles if you have to richen it up. you also need to inspect the carb boots closely to look for air leaks. Get some spray carb cleaner and spray lightly around the boots to look for leaks, engine speed will pick up if you have a leak when you spray.
 
Thanks, I did the boot test, I should have mentioned. No signs of leaks, but I will definitely take the pilot back to 40 and test the WOT with the choke for the main, if it is bogging down and bogs down even more with the choke at WOT, I'll bump the main down some. Thanks for the speedy reply...
 
No needle clips on these carbs, you will have to use washer shims on the needles if you have to richen it up.


Is there any procedure to shim the needles? I have a 1977 CB750K and I have seen people talk about shimming the needles a few times but nothing more than that it needs to be done.
 
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