Carb issue I think but could it be ignition?

[Jethro]

Hi trying to finish up my CA77 resto. Got everything together and ran it a few times. Fixed the head gasket leak. One problem I'm having is that the engine surges unless the choke is closed. I'm kind of confused though because I totally went through the carb, set the float to 26.5mm (old style 22 carb with the round bow) removed all internals and cleaned everything really well. Made sure all passages were clear. With the idle speed screw backed all the way out and the idle mixture screw at 1.5 turns out from bottom it still surges. Turning the idle screw either direction makes almost no difference. It still surges. I even moved the main needle to the highest position. I have one of those foam style filters that you oil, then squeeze out the extra. I run those on my CL350 with no issues. I'm kind of wondering if it might be an ignition problem. I set the points to specs when I overhauled it but it has a new points cam seal which I'm assuming could throw things off a bit if you're not careful. If the timing is too far advanced can that cause surging?

Any pointers would be great.

Thanks, Jethro

[davomoto]

Jethro,

Make sure point gap and timing are spot on before adjusting carb. I would think it would run leaner with the pod filter. Have you checked the color of the plugs? What size jets? Did you blow all of the passages in the carb out with compressed air?

Davo

[Jethro]

Thanks for the reply davo. Yeah I blew them all out and totally went through the carb and made sure everything was good to go. I also am assuming that the filter would run the engine maybe a bit more lean but not to the point that it surges as bad as it does. I also have those same air filters on my CL350 without any problems. Since the engine will only run at idle speed with the choke on, the plugs are black. The second I open the choke back up it will surge to the point that I just shut it off because it runs so high. I don't have my bike with me this weekend (it's at work) but when I overhauled the engine I set the points gap and timing spot on with a vom. Like I said though I totally went through the carb and everything is up to specs on it. The main thing I'm wondering about is if the points cam seal is putting some resistance on the cam and adversely effecting the timing advance being that seal is brand new.

Jethro

[mike horvath]

Hey Jethro,
Just a thought here...is it possible the engine is starving for fuel, like when you forget to turn the petcock to "ON" ? My engine will rev up pretty good under those cicumstances and that's my cue to check the lever position, and it will always be "OFF" when the surge ocurrs. There has also been a lot of talk recently with carb slides being inadvertantly installed backwards, and over tightening of the carb body mounting nuts with that type of result. I don't think the cam seals would exert that kind of pressure to effect the timing, but I'm not an expert.