I have been reluctant to change the idle screws too drastically because the manual says 1 turn out but I will start tweaking more with the screws.
Stock settings apply to a totally stock bike. The exhaust change "may" require a change to those stock ideal settings.
At any rate, on non-accelerator pump carbs, the air bleed screws are set in relation to engine pick up from idle. The idle must be set on the rich side rich to offset the sudden inrush of air and the jet starvation from the throat vacuum dropping as the slides are suddenly opened.
I've been doing my plug chop at the end of my ride which usually has me riding low throttle for about 10 minutes before home. Is there a better way for me to do the plug chop? Most of what I've read on the sight about plug chop is full throttle then kill the engine.
The whole idea of the plug chop is to isolate which portion of the carb is dominating the fuel mix and this changes with the throttle position.
For example: a main jet can be set too small, a plug chop at WOT would show lean deposits on the plugs. However, the slide needle can be set too high, which means the plugs would be carbon black when operating at mid throttle. The pilot system (air bleed and air screw) can also be set too rich leaving soot on the plug during throttle closed and and 1/4 throttle position.
If you operate the engine in all these ranges, the plug deposits give you only a general indication or average of all throttle positions used since installed in the engine.
The plug chop procedure is to arrive at your test track with the engine at operating temperature. Then install fresh, clean spark plugs, start a wail down the track at WOT, allowing enough time for deposits to accumulate on the spark plugs (1/4 to 1/2 mile with the engine fully loaded to full power). Then simultaneously hit the kill switch and pull in the clutch, coast to a stop, pull the plugs and read them. They will have the deposit pattern of the engine under load at full throttle. Only the main jet was used during the run, so the deposit pattern applies directly to the main jet.
After getting the main jet adjusted for ideal combustion, you then move on to adjusting the mid throttle in a similar way using clean new plugs. Note the the engine must be loaded so as to make the most power at that throttle setting (a steep hill is nice). Again you are looking for spark deposit that tell you whether the needles are providing soot or no deposits on the spark plugs. This will tell you how to adjust the slide needle up or down, to get the ideal mixture at the mid throttle position.
Then the taper of the needle is checked at the 2/3 and 1/3 throttle positions, in turn. Plug chops at those positions under power. Read/adjust.
Finally, the air bleeds are adjusted to that in top gear at idle, the throttle can be whacked to 1/2 of total travel and the engine will pick up smoothly and reliably with burble or stumble.
I will point out that a dyno run will give a fuel map over the entire operating range, allow one to attack or adjust multiple fuel metering points after a single test run.
Very little throttle, maybe 1/8 to 1/4.
Then those are the fuel metering circuits that have dominated the plug deposit patterns, leaving little or no information about slide needles or main jet settings.
I didn't think about redoing with the new clamps. When I hook up my gauges, would more vacuum on the rich cylinder (#1) cause it to run rich?
The vacuum (or pressure differential) is what pulls the fuel up from the bowls.
(technocrats, stand down) For a given amount of air passing through the carb throat, varying the vacuum level directly changes the amount of fuel drawn through fuel jets, and thus the air/fuel ratio.
Having said that, I still maintain it is pointless to do any fine tuning until all the carbs/cylinders are behaving the same. Because after that, any changes will be applied to all carbs equally.
Hope this helps,
