Switched from 4 into 2 no baffles to 4 into 1 with baffles.
Stock air box. 7A carbs.
Currently using 115/38 jets. Do I need to change jet size? Having all kinds of starting issues. Wasn't easy with the other pipes either. I'm going to do do 3000 miles maintenance (again) and start from scratch. Plugs look rich even though I had previously moved one notch on the needles to the leaner direction. I'd like to start the process with the most logical jet size based on the current set up. Thanks!
Try a #40 pilot jet instead. You were likely at the very 'edge' of correct mixture with the #38 pilot jet before. Believe this or not (your choice, but 'tis true), having a too-lean pilot jet will cause dark sparkplugs because the engine is lightly 'missing' on successive idle-speed firings until enough residual fuel is left to fire more 'fully', at which stroke it is then too rich (effectively fully firing about 1 in 3 cycles) as the carbon in the cylinder head holds the unburned fuel in this situation - until it fires. The idle-air screw gets set to 'best idle' so the too-lean mix will make the engine idle, but it is 'flat' just off idle, especially when cold, and is not linear in throttle response due to the too-lean low end.
You can also modify the low-speed performance by altering the float levels in the 7A series carbs (aka 657A). Raising the float level of the sidestand-side float to 25mm instead of 26mm, while leaving the other one at 26mm, will help linearize the throttle response, too, especially with today's fuels that burn cold (if the carb has brass floats, Honda originally set them staggered like this). Also: look closely in the 7A carbs: many (if not most) have tiny slivers of and edge raised above the float-bowl-gasket's surface, inside the gasket, adjacent to the notches on the sides of the carb bodies. THIS is the reference edge for setting float depths, if your carbs have them - not the gasket's mounting surface. This 'edge' is usually 0.5-2mm higher than the gasket surface, so it is important to use it, if it is there, to set the depths.
