Hi all,
I am new to this forum. I frequent hondatwins.net as well as the soh4forum. I have also checked out a lot of the posts on this one over the years, just never joined up as I haven't had a 305 that I have kept long term before.
Anyways, A little background on the bike. I just completed a complete tear down and rebuild keeping it mostly stock. One of the changes was to the CL77 exhaust. No muffler, but it does have the baffles. I am also running the charlie's place electronic ignition and dyna coils. I am using the reproduction stock air filters and rubber air tubes.
I used to have a CL77 that I got running well using Ed Moore's tuning recipe and I've been through that procedure on this bike many times, as well.
Initially, I was getting a lot of popping at idle and deceleration from the left carb only. The right seemed to be running smoothly. No amount of adjustment of either the slide screw or the air mixture screw really made a difference. I checked for air leaks between the carb and head and found nothing. I tried cleaning the carbs over and over and nothing helped. The left carb did appear to have excessive wear in the slide bore and ultimately I decided to buy another set of carbs. I could only find carbs for the later bikes so I replaced both carbs so I would have a matching set. After thoroughly cleaning the new carbs and installing them, I now am having the same problem, but on the right side.
I am using all factory brass, 135 mains, 42 pilots, needles on the 2nd spot from the bottom. I have installed new orings between the carbs and insulators and between the insulators and the head. I have checked for cracks in the insulators, there are none. The carbs are installed with the nuts tightened down just past finger tight. I've also check for leaks and didn't find any. The cable adjustments are set so the slides move evenly with a little slack. I believe the slides are set evenly as well. The right side is popping at idle when I first start it up but then stops once it warms up. But it does pop on deceleration and the idle will hang just a little. from my understanding these are both symptoms of a lean condition on the idle circuit. It idles best with the air screws at 1 turn out, but i tried turning them in a little more. That made it idle worse, and did not fix the issue. When I turned them out further, it made it idle a little worse and pop a lot more. Finally, I decided to give bigger pilots a shot so I ordered Keihin 45 pilots. With these installed, air screw still at 1 turn out, I have no popping at idle during start up or after its warmed up. It does still pop on deceleration, but only slightly and only when I have it revved really high. The idle still hangs as well. turning the air screws in or out gives the same results as with the 42 pilots. I put in new plugs after my last round of adjustments. The left one has a lot of carbon on it and looks like that side is rich. The right side has carbon around the outside but is white on the tip suggesting to me that its running lean on the right. I have both floats set so I can just see the top of the main jet holder with the float just resting on but not pressing in the float needle. Both carbs are set equally, so I'm having a hard time understanding why I'm only having issues on one side. The slide bore does not look to be worn excessively like the old carb, but I fear this might be the issue. Any suggestions of things I could try or any ideas what the issue could be?
Thanks,
Dave
64 cb77 - popping on deceleration hanging idle
Re: 64 cb77 - popping on deceleration hanging idlePoints timing and one slide is a bit (I say BIT) higher than the other.
Go back to stock and tune the points. ..........lm
Re: 64 cb77 - popping on deceleration hanging idleI can give that a try. Back to stock on the pilots too? I appreciate the help, Dave
Re: 64 cb77 - popping on deceleration hanging idleYes. ..............lm
I got it sorted out. It turns out, the left carb was too tight causing the slide to hang up a bit and slowly fall, it was also just a hair higher than the right. After correcting that and a slight adjustment to the timing, it's running great. I went back to the 42 pilot jets, but stuck with the electronic ignition.
Thank you very much for the help in getting me in the right direction. You were right on
You are welcome. ...........lm
Popping at idle and deceleratonDave and LoudMouse
I am really glad to hear someone is having similar problems. I have a 1967 CL77. I have the same popping at deceleration, and it won't idle at all. It runs great at high RPM, but pretty bad a low and especially at low RPM and deceleration. The carbs are original. I bought replacement kits for each, everything replaced. The kit gave me a 130 for main jet and39 for slow or pilot jet. The jet I took out was a 38. The carbs are original and the slides show some wear, not excessive. Adjusting the throttle stop or idle screw seems to have little to no impact, neither does the air screw next to it. There is some wear in the slide where the throttle stop screw comes up against it in the slot. I have replaced points, plugs, have had trouble getting the timing set. The plugs are black and sooty, but not wet. The right side is worse than the left, and the right side tends to smoke (black smoke) some, not a lot. My thinking is that sooty black plugs mean too rich? I adjusted the needle to the next to the last slot at the top, still too rich. I wondered if it was too lean making it pop, but how can that be if it is running too rich? The cables seem to operate the slides in unison. Where did you find the carbs you bought? Also where are you finding the different jets? All I have found are the carb kits that I ordered, not individual jets. Driving me nuts, fun to ride in 4th gear at steady RPM, but things go to hell as soon as I back off and start shifting down. I will try some of the things you said, maybe loosen the carb nuts at the head. I am stuck, any thoughts either of you have would be great.
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