CL 77 carb balancing
CL 77 carb balancingany references or descriptions for a carb balancing procedurre equipment too) for a 65 - 66 bike. new top end but stuttering on the left side. Thanks men.
Start with a visual balance. Back the idle screws out so the slides are all thee way down. Rotate the throttle and have a look at the slides. I usually look at one and feel the other. Both should lift at the same time. Some use 2 drill bits of the same size and watch that they move at the same time. If adjustment is needed you use the carb top adjusters. Make sure you dont raise them so much that the slides no longer bottom out.
After the cables are synched you can set the idle speed. Turn them in so they raise the slides just a bit and start the bike. Get it idling at the desired speed and then check to see if carbs are balanced at idle. Couple ways to do this. Sometimes I just feel the pressure coming out of the mufflers, but on a Scrambler with the muffler on that is hard to do unless you take it off. Sometimes you can really feel a difference in exhaust exiting the pipes and sometimes not so much. If it feels pretty equal you are ok. Balance at idle isn't really all that important as you aren't really tuning for performance at idle. Another method is to pull the plug wire on one side and listen to the RPM's. The engine might die or it might chug along at a really low RPM. Put that wire back on and pull the other one. Hopefully the same thing happens as what the other one did. To check higher speed synch and verify your cable are pulling evenly I do the same plug wire pull. (careful not to get shocked) I run the bike at roughly 3000 rpms and pull a plug wire and listen to the sound or look at the tach if it has one. Then do the same for the other plug at the same rpm. If you have no tach just make sure you are turning the throttle to the same location each time. The drop in rpm should be the same on each side. The ideal setup would be to measure vacuum at each carb but the carbs on most bikes from the mid 70's and earlier usually don't have the ports to allow for this. Kevin
Another way to consider is remove both rubber air filter tubes and use an approx 1/2" bore rubber/plastic hose to listen to the intake 'hiss' and balance the cables to give an identical sound, I used to do this on twin-carb cars in the 60's.
1977 CB400F
1973 CL175 1976 XL175 - Sold 1964 CL72 1966 CA78 It would be pretty easy to put a vacuum adapter in each of the carb insulators and use a vacuum gauge.
Back in the 80's I made my own carb balancing manometer with ½ inch clear plastic tubing on a wooden plank. These work pretty well, too.. http://www.carbtune.co.uk G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
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