Topic: Need help diagnosing running problem with 750K carbs

[vorhese]

My '77 750A came with 657B carbs with 110 main and 40 pilot jets, 1 turn out on air screw. I just thoroughly went through the carbs, valves, cam chain, new plugs, and checked timing.  It starts right up and revs high in neutral.  Once I put it in low, it idles much lower, and it sounds like it wants to stall when I twist the gas.  Also it wants to move forward with no throttle.  It just does not feel right.  Has anyone had any luck with putting the roundslides on and could give me some pointers on what I need to do?

[dave the welder]

I put a set of round tops on my 77.the best thing I ever did to it.you can adjust the idle speed in neutrl but I did it in low.just like your car when you put it in gear it will slow a little.the original carbs had a gizmo that raised the idle to compensate for that.i am running the same setup you have with the exception of 115 mains.that is because that was in the carbs when I got them.if you crank the throttle open REAL fast it will seem like it wants to stall. the original carbs also had an accelator pump to give a squirt of fuel when you opened the throttle. again the round tops do not.i just open slowly just a little and when it gets moving I open it more.this works even when I am riding 2 up.it is  going to be slow  taking  off but that's the nature of the bast.the gearing is aproxamitly the same as taking off in 2nd gear on a regular 750 then shifting into 4th. once you get rolling its a blast

[vorhese]

I discovered I had an intermittent bad 1-4 coil power connection and 2 poorly connecting spark plug boots, and that made a world of difference. But the biggest difference made by packing the open exhaust with steel wool. It went from a blargh to WURRRR WURRR. Unfortunately the steel wool wont stay in, so I'm on the hunt for some good mufflers.  Thanks again!

[vorhese]

Is there really no way around the 750K carb hesitation at take off?  It's a major disappoinment for me because of living in a city with so much stop and go. I just upped the pilots to 42 because I was having a bit of lean popping cruising around, and I was hoping that would give it some extra oomph at take off, but no luck. 

[dave the welder]

nope just roll the throttle slow until you are moving then give it a little more.your other option is use keyhole carbs off the later 750 k's and f model. you will need the appropeate intake boots.those carbs use a accelerator pump

[POPS 911]

MUFFLERS for CB750 Hondamatic = 1976 has stock 4-1 so buy one. 1977-78 has stock two mufflers so buy two = 24" long EMGO # 80-8413 W/ REMOVABLE BAFFELS or you can adjust the exhaust flow for tuning = $60.94 each w/free shipping from GRAND RAPIDS MICH. Found on E-BAY and they are brand new and fit perfect on my 1978 cb750a.  I have 1= 1976 CB750A w/4-1 and 5= 1978 CB750A w/ 4 into two exhaust. You must set those carbs up with the motor running, off  vacuum ports on each carb and 4 vacuum gauges to get the balance dead on the money, 1-2 main jet size up helps on the bog off the start to be tuned to the muffler [ opened or tuning holes or disc. ]